CN109412014B

CN109412014B - Wavelength calibration device of tunable laser and corresponding wavelength calibration method

Info

Publication number: CN109412014B
Application number: CN201811453987.7A
Authority: CN
Inventors: 汤学胜; 余斯佳
Original assignee: Accelink Technologies Co Ltd; Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
Current assignee: Accelink Technologies Co Ltd; Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
Priority date: 2018-11-30
Filing date: 2018-11-30
Publication date: 2021-03-23
Anticipated expiration: 2038-11-30
Also published as: CN109412014A

Abstract

The invention discloses a wavelength calibration device of a tunable laser and a corresponding wavelength calibration method, wherein the wavelength calibration device comprises a system control center, a comb filter and an optical power detector; the system control center is used for outputting wavelength control signals; the comb filter comprises an input port, a first output port and a second output port, the first output port and the second output port correspond to a filtering spectrum and the filtering spectrum comprises a pass band and a stop band which are arranged at preset intervals; the optical power detector is used for detecting the main mode spectral power of the laser and the side mode spectral power of the laser; and the system control center is used for acquiring the main mode spectral power and the side mode spectral power, and establishing a wavelength calibration lookup table when the output wavelength of the tunable laser is determined to be aligned with the standard wavelength according to the side mode rejection ratio. The invention adopts the specific comb filter, avoids the operation of repeatedly switching the central wavelength of the filter, can save a large amount of test time, can avoid misoperation at the same time, and improves the test accuracy.

Description

Wavelength calibration device of tunable laser and corresponding wavelength calibration method

Technical Field

The invention belongs to the field of lasers, and particularly relates to a wavelength calibration device of a tunable laser and a corresponding wavelength calibration method.

Background

The tunable semiconductor laser has a function of dynamically adjusting output wavelength, and is regarded as one of indispensable key devices in a dense wavelength division multiplexing optical fiber communication system and an intelligent reconfigurable optical network. Among them, tunable lasers with Distributed feedback (DBR) and similar structures with fast wavelength switching speed have attracted attention as a typical and important monolithic optical device with a large tuning range and high output spectral quality. Tunable lasers with DBRs and similar structures achieve wavelength tuning by changing the index of refraction of the waveguide material through injection current. The simplest three-section DBR-type tunable laser consists of three parts: an active region, a phase shift region and a grating region. The DBR grating area is equivalent to a reflector with the reflectivity changing along with the wavelength, is used for selecting a longitudinal mode, and changes the Bragg wavelength of a reflection peak of the reflector by injecting different currents; the phase shift region is used for fine tuning adjustment of wavelength, and different currents are injected into the phase shift region to change the longitudinal mode resonance wavelength of the laser, so that the wavelength tuning of the laser is realized in cooperation with the phase shift region and the longitudinal mode resonance wavelength.

However, only a limited refractive index can be changed by the injection current, and the wavelength tuning range of the three-section DBR tunable laser is generally around 10 nm. In order to improve the wavelength tuning range, various four-segment tunable DBR lasers have come into use based on the vernier effect, and most typically, a Sampled Grating DBR laser (SGDBR) and a Super structured Grating DBR laser (SSGDBR) are used. A typical four-section DBR semiconductor laser consists of four sections: a front grating reflection region, an active region (gain region), a phase shift region and a back grating reflection region. The front grating reflection area and the front grating reflection area have comb-shaped reflection spectrums with the maximum periodicity in wavelength, different grating periods are designed and manufactured, and the generated comb-shaped reflection spectrum sequences have slightly different peak wavelength intervals. When a pair of spectral peaks in two comb-shaped reflection spectrum sequences coincide, a single output wavelength can be selected. Similar to a three-section DBR laser, the effective refractive index of the waveguide of the grating region can be changed by injecting current into the front grating reflection region and the rear grating reflection region, and the position of the comb-shaped reflection spectrum peak is controlled; the phase shift region is used for changing the longitudinal mode resonance wavelength of the laser, different grating reflection peaks and cavity modes can be aligned by simultaneously changing the tuning currents of the front grating reflection region, the rear grating reflection region and the phase shift region, and the tuning mode similar to the vernier effect can realize a larger wavelength tuning range under the condition of small injection current.

Four-section DBR lasers have gradually become the mainstream solution for Integrated Tunable Laser Assemblies (ITLA) in the digital coherent optical communication market. An Integrated Tunable Laser Assembly (ITLA) can output a plurality of different wavelength channels (at least greater than 80) covering the C-band or L-band, both wavelength values and channel spacing meeting ITU-T (ITU-T for ITU Telecommunication Standardization Sector) requirements. For a four-section DBR tunable laser component (ITLA), in order to control the laser wavelength on a wavelength channel specified by ITU-T, three currents of a front grating reflection area, a rear grating reflection area and a phase shifting area need to be scanned and tested simultaneously, and a wavelength calibration parameter comparison table comprising ITU-T wavelength-3 control current combinations is generated. However, the scan test of all the current combinations (front and back reflection gratings and phase shift region driving current) often takes a very long time. Wavelength calibration of tunable laser components (ITLAs) is one of the bottlenecks in achieving large-scale product manufacturing, and how to achieve fast and efficient wavelength calibration tests and establish an optimal driving current combination and target wavelength comparison table is very important in the manufacturing process.

In various fast and efficient calibration methods for tunable lasers, single characteristics or combination characteristics such as output wavelength, optical power, Side-Mode Suppression Ratio (abbreviated as SMSR) of output spectrum, and junction voltage of active region can be used as the basis for establishing an optimal comparison table of drive current combination and target wavelength. In practice, the SMSR of a tunable laser can be recorded by a spectrometer, but the spectrometer scan is a rather slow process, and a complete wavelength calibration takes a very long time, resulting in low production efficiency.

In order to reduce the time for wavelength calibration, patent publication No. CN105826811A discloses a method and an apparatus for characterizing a tunable laser based on an optimization algorithm, in which output light of the tunable laser is divided into two paths by a splitter, one path passes through a tunable optical band-pass filter capable of filtering optical power other than a target wavelength, the other path passes through a tunable optical band-stop filter capable of filtering optical power at the target wavelength, and then the two paths are connected to a detector respectively, the ratio of the optical power P1 passing through the optical band-pass filter and the optical power P2 passing through the optical band-stop filter is used as an optimization criterion of the SMSR, and a driving current combination required for stably outputting the target wavelength is found by the optimization algorithm.

The main disadvantages of the patented method are: when a target channel is replaced, the tunable optical band-pass filter and the tunable optical band-stop filter need to synchronously switch the central wavelength, the process of switching the central wavelength of the tunable filter can further prolong the test time, the calibration time is too long, and the effect of quick calibration cannot be achieved. In addition, in the actual calibration process, misoperation is easy to occur, which causes errors in switching the center wavelength of the filter, further causes errors in the comparison table of the driving current combination and the target wavelength, and causes that an operator cannot adjust the output wavelength of the tunable laser according to the comparison table. In addition, tunable optical bandpass filters and tunable optical bandstop filters are not common, require customization, are expensive, and are not suitable for industrial production.

In view of the above, overcoming the drawbacks of the prior art is an urgent problem in the art.

Disclosure of Invention

The invention provides a wavelength calibration device of a tunable laser and a corresponding wavelength calibration method aiming at overcoming the defects or the improvement requirements in the prior art, and aims to adopt a specific comb filter to filter a plurality of laser with different wavelengths so as to obtain the corresponding side mode rejection ratio, avoid the operation of repeatedly switching the central wavelength of the filter, save a large amount of test time, avoid misoperation and improve the test accuracy, thereby solving the technical problems of overlong wavelength calibration test time, complicated operation and easy occurrence of wavelength calibration errors in the prior art.

To achieve the above object, according to one aspect of the present invention, there is provided a wavelength scaling apparatus for a tunable laser, including: the system comprises a system control center, a comb filter and an optical power detector;

the system control center is used for outputting a wavelength control signal so as to control the tunable laser to output laser matched with the wavelength control signal, wherein the spectrum corresponding to the laser comprises a main mode spectrum and a side mode spectrum;

the comb filter comprises an input port, a first output port and a second output port, the first output port of the comb filter and the second output port of the comb filter respectively comprise a pass band and a stop band which are arranged according to preset intervals in corresponding filtering spectrums so as to filter the laser, wherein the preset intervals are equal to the wavelength channel intervals of the tunable laser multiplied by preset multiples;

an input port of the comb filter is used for receiving the laser, a first output port of the comb filter is used for outputting the laser for filtering the side mode spectrum, and a second output port of the comb filter is used for outputting the laser for filtering the main mode spectrum;

the optical power detector is used for detecting the main mode spectral power of the laser output through the first output port and the side mode spectral power of the laser output through the second output port;

and the system control center is used for acquiring the main mode spectral power and the side mode spectral power according to the optical power detector to obtain a side mode suppression ratio, and establishing a wavelength calibration lookup table after determining that the output wavelength of the tunable laser is aligned with the standard wavelength according to the side mode suppression ratio.

Preferably, the preset interval is twice the wavelength channel interval of the tunable laser;

the number of the comb filters is two, and the comb filters specifically comprise a first comb filter and a second comb filter;

the wavelength interval between the extreme value wavelength in the filtering spectrum corresponding to the first output port of the first comb filter and the extreme value wavelength in the filtering spectrum corresponding to the first output port of the second comb filter is equal to the wavelength channel interval of the tunable laser;

the wavelength interval between the extreme wavelength in the filtered spectrum corresponding to the second output port of the first comb filter and the extreme wavelength in the filtered spectrum corresponding to the second output port of the second comb filter is equal to the wavelength channel interval of the tunable laser.

Preferably, the wavelength scaling device of the tunable laser further comprises an optical beam splitter;

the optical beam splitter is used for dividing the laser into two paths, wherein one path of laser is input to the input port of the first comb filter, and the other path of laser is input to the input port of the second comb filter.

Preferably, a filtered spectrum corresponding to the first output port of the first comb filter and a filtered spectrum corresponding to the second output port of the first comb filter are in a complementary relationship;

a filtering spectrum corresponding to a first output port of the first comb filter is a narrow-bandwidth comb spectrum, a filtering spectrum corresponding to a second output port of the first comb filter is a wide-bandwidth comb spectrum, a peak wavelength of the narrow-bandwidth comb spectrum is aligned with a standard wavelength, and a valley wavelength of the wide-bandwidth comb spectrum is aligned with the standard wavelength; or

A filtering spectrum corresponding to a first output port of the first comb filter is a wide-bandwidth comb spectrum, a filtering spectrum corresponding to a second output port of the first comb filter is a narrow-bandwidth comb spectrum, a peak wavelength of the narrow-bandwidth comb spectrum is aligned with a standard wavelength, and a valley wavelength of the wide-bandwidth comb spectrum is aligned with the standard wavelength;

wherein a passband of the narrow bandwidth comb spectrum corresponds to a stopband of the wide bandwidth comb spectrum, a stopband of the narrow bandwidth comb spectrum corresponds to a passband of the wide bandwidth comb spectrum, and a peak wavelength of the narrow bandwidth comb spectrum is aligned with a valley wavelength of the wide bandwidth comb spectrum.

Preferably, a filtered spectrum corresponding to the first output port of the second comb filter and a filtered spectrum corresponding to the second output port of the second comb filter are in a complementary relationship;

a filtering spectrum corresponding to a first output port of the second comb filter is a narrow-bandwidth comb spectrum, a filtering spectrum corresponding to a second output port of the second comb filter is a wide-bandwidth comb spectrum, a peak wavelength of the narrow-bandwidth comb spectrum is aligned with a standard wavelength, and a valley wavelength of the wide-bandwidth comb spectrum is aligned with the standard wavelength; or

A filtering spectrum corresponding to a first output port of the second comb filter is a wide-bandwidth comb spectrum, a filtering spectrum corresponding to a second output port of the second comb filter is a narrow-bandwidth comb spectrum, a peak wavelength of the narrow-bandwidth comb spectrum is aligned with a standard wavelength, and a valley wavelength of the wide-bandwidth comb spectrum is aligned with the standard wavelength;

Preferably, the system control center comprises a setting unit, a recording unit and a processing unit;

the setting unit is used for generating a wavelength control signal and carrying out scanning test on the tunable laser according to the wavelength control signal;

the recording unit is used for recording the optical power value detected by the optical power detector and establishing a scanning data recording table, wherein the scanning data recording table comprises a wavelength control signal and an optical power value corresponding to the wavelength control signal;

the processing unit is used for obtaining the side mode suppression ratio of the laser corresponding to the wavelength control signal according to the scanning data record table, screening out a target side mode suppression ratio of which the side mode suppression ratio is not less than a screening threshold value, and establishing an initial wavelength calibration query table according to the target side mode suppression ratio and the wavelength control signal corresponding to the target side mode suppression ratio.

Preferably, the system control center is further configured to control the tunable laser to emit laser according to the initial wavelength calibration lookup table, measure an actual wavelength and optical power of the laser triggered by the wavelength control signal, and establish a final wavelength calibration lookup table according to the wavelength control signal, the actual wavelength, and the optical power.

According to another aspect of the present invention, there is provided a method of wavelength scaling of a tunable laser, the method comprising:

performing scanning test on a tunable laser based on a wavelength control signal, and driving the tunable laser to output laser matched with the wavelength control signal, wherein a spectrum corresponding to the laser comprises a main mode spectrum and a side mode spectrum;

the first output port of the comb filter outputs laser for filtering side mode spectrum, and the second output port of the comb filter outputs laser for filtering main mode spectrum, wherein the first output port of the comb filter and the second output port of the comb filter correspond to filtering spectrums which respectively comprise a pass band and a stop band which are arranged according to a preset interval, and the preset interval is equal to the multiplication of the wavelength channel interval of the tunable laser by a preset multiple;

detecting a main mode spectral power of the laser output through the first output port of the comb filter, and detecting a side mode spectral power of the laser output through the second output port of the comb filter;

obtaining the main mode spectral power and the side mode spectral power to obtain a side mode rejection ratio;

and establishing a wavelength calibration lookup table after determining that the output wavelength of the tunable laser is aligned with the standard wavelength according to the side mode suppression ratio.

Preferably, after determining that the output wavelength of the tunable laser is aligned with the standard wavelength according to the side-mode suppression ratio, establishing a wavelength calibration lookup table includes:

judging whether the side mode suppression ratio is not less than a screening threshold value;

if the side mode suppression ratio is not smaller than the screening threshold, reserving the wavelength control signal corresponding to the side mode suppression ratio, and establishing an initial calibration lookup table according to the side mode suppression ratio and the wavelength control signal corresponding to the side mode suppression ratio.

controlling the tunable laser to emit laser according to the initial wavelength calibration lookup table;

measuring the actual wavelength and the optical power of the laser triggered by the wavelength control signal;

and establishing a final wavelength calibration lookup table according to the wavelength control signal, the actual wavelength and the optical power.

Generally, compared with the prior art, the technical scheme of the invention has the following beneficial effects: the invention adopts the three-port comb filter to filter the laser, and because the corresponding filter spectrums of the first output port and the second output port respectively comprise the pass band and the stop band which are arranged according to the preset interval, and the preset interval is the wavelength channel interval of the tunable laser multiplied by the preset multiple, the comb filter can filter the laser with a plurality of different wavelengths, and separate out the main mode spectrum and the side mode spectrum so as to obtain the side mode rejection ratio of the laser. When the tunable laser is subjected to scanning test, the operation of repeatedly switching the central wavelength of the filter is avoided, a large amount of test time can be saved, misoperation can be avoided, and the test accuracy is improved. On the other hand, whether the output wavelength of the tunable laser is aligned with the standard wavelength or not is preliminarily judged according to the side mode suppression ratio, a large amount of useless test data can be eliminated, the data volume of a subsequent wavelength calibration test is reduced, and the test efficiency is improved. Moreover, the comb filter has low cost and easy manufacture, and is suitable for industrial production.

Drawings

FIG. 1 is a diagram of a spectrum of laser light output by a tunable laser according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a wavelength scaling apparatus for a tunable laser according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of another wavelength scaling apparatus for a tunable laser according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a system control center according to an embodiment of the present invention;

FIG. 5a is a diagram of a spectrum of a first comb filter according to an embodiment of the present invention;

FIG. 5b is a diagram of a second comb filter according to an embodiment of the present invention;

FIG. 6a is a diagram of an embodiment of the present invention providing a first comb filter based output wavelength λ_iA schematic diagram of laser filtering;

FIG. 6b is a diagram of an embodiment of the present invention providing a second comb filter based output wavelength λ_i+1Schematic diagram of the comparison of the laser filtering;

fig. 7a is a schematic structural diagram of a comb filter according to an embodiment of the present invention;

fig. 7b is a schematic structural diagram of another comb filter provided in the embodiment of the present invention;

fig. 8 is a schematic flowchart of a wavelength scaling method for a tunable laser according to an embodiment of the present invention;

fig. 9 is a schematic flowchart of step 84 in fig. 8 according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1:

in a practical application scenario, the tunable laser may control to output a plurality of wavelength channels (at least more than 80 wavelength channels) covering C-band or L-band, and the wavelength value of each wavelength channel and the interval between the wavelength channels satisfy the requirements of ITU-T. On the other hand, the wavelength interval between the main mode and the side mode in the filtering spectrogram corresponding to the tunable laser is approximately equal to the minimum wavelength channel interval of the tunable laser, wherein the wavelength channel interval refers to the wavelength difference between adjacent output wavelengths. For example, the minimum wavelength channel spacing of a 50G tunable laser is 0.4nm, and as shown in fig. 1, the wavelength separation between the main mode and the side mode in the spectrum of the laser output from the 50G tunable laser is about 0.4 nm. The minimum wavelength channel interval of the 100G tunable laser is 0.8nm, and in a spectrogram of laser output by the 100G tunable laser, the wavelength interval between a main mode and a side mode is about 0.8 nm; the minimum wavelength channel interval of the 25G tunable laser is 0.2nm, and in a spectrogram of laser output by the 25G tunable laser, the wavelength interval between a main mode and a side mode is about 0.2 nm. The wavelength channel interval refers to an interval between adjacent wavelength channels in the output wavelength of the tunable laser.

Based on the foregoing characteristics of the spectrogram of the tunable laser, the invention provides a wavelength calibration device of the tunable laser, when the wavelength calibration device of the tunable laser is used for scanning test of the tunable laser, because the comb filter can perform filtering processing on a plurality of lasers with different wavelengths, the tunable laser is controlled to output the lasers with different wavelengths only by adjusting the wavelength control signal according to the test requirement, the operation of repeatedly switching the central wavelength of the filter is avoided, a large amount of test time can be saved, and the test efficiency is improved. Meanwhile, misoperation can be avoided, and the accuracy of the test is improved.

One embodiment of the wavelength scaling device for a tunable laser, and the corresponding operating principle, will be described with reference to fig. 2 to 7 b.

In this embodiment, the wavelength scaling apparatus for a tunable laser includes: a system control center 10, a comb filter 11 and an optical power detector 12. The system control center 10 is configured to be connected to a tunable laser 20 to be wavelength-scaled, the input port com of the comb filter 11 is configured to be connected to the tunable laser 20 to be wavelength-scaled, the output port of the comb filter 11 is connected to the input port of the optical power detector 12, and the output port of the optical power detector 12 is further connected to the system control center 10.

The comb filter 11 includes an input port com, a first output port1, and a second output port2, the first output port1 of the comb filter 11 and the second output port2 of the comb filter 11 each include a pass band and a stop band arranged at a preset interval in a corresponding filtering spectrum, so as to filter the laser light emitted by the tunable laser 20, where the preset interval is a wavelength difference between center wavelengths of adjacent pass bands, and the preset interval is equal to a wavelength channel interval of the tunable laser 20 multiplied by a preset multiple. In an actual application scenario, the preset multiple may be set according to an actual situation, and it is ensured that the corresponding output port only outputs a main mode spectrum or a side mode spectrum of the laser. This is illustrated in the following by way of example.

In a practical application scenario, the system control center 10 is configured to output a wavelength control signal to control the tunable laser 20 to output laser matched with the wavelength control signal, where different wavelength control signals correspondingly excite the tunable laser 20 to emit laser with different wavelengths, so as to achieve a tuning purpose, and perform wavelength calibration on the laser with different wavelengths respectively. The spectrum corresponding to the laser includes a main mode spectrum and a side mode spectrum, the input port com of the comb filter 11 is configured to receive the laser, the first output port1 is configured to output the laser with the side mode spectrum filtered, and the second output port2 is configured to output the laser with the main mode spectrum filtered.

The optical power detector 12 is configured to detect a main mode spectral power of the laser light output through the first output port1 and a side mode spectral power of the laser light output through the second output port 2. In a practical application scenario, the optical power detector 12 may be a single device including a plurality of independent sub-detectors, so as to detect the power of the laser output from the output port correspondingly. Alternatively, the number of the optical power detectors 12 is multiple, and an optical power detection array formed by multiple optical power detectors 12 is used to detect the power of the laser light output from the corresponding output port.

The system control center 10 is configured to obtain the main mode spectral power and the side mode spectral power to obtain a side mode suppression ratio, and establish a wavelength calibration lookup table after determining that the output wavelength of the tunable laser 20 is aligned with a standard wavelength (ITU wavelength) according to the side mode suppression ratio. The standard wavelength is a wavelength divided according to the standard of ITU-T.

In a practical application scenario, the filtered spectrum corresponding to the first output port1 and the filtered spectrum corresponding to the second output port2 are in a complementary relationship. In one embodiment, the filtered spectrum corresponding to the first output port1 is a narrow bandwidth comb spectrum, the filtered spectrum corresponding to the second output port2 is a wide bandwidth comb spectrum, the peak wavelength of the narrow bandwidth comb spectrum is aligned with the standard wavelength, and the valley wavelength of the wide bandwidth comb spectrum is aligned with the standard wavelength. The peak wavelength is the central wavelength corresponding to the pass band, and the valley wavelength is the central wavelength corresponding to the stop band.

In another embodiment, the filtered spectrum corresponding to the first output port1 is a wide bandwidth comb spectrum, and the filtered spectrum corresponding to the second output port2 is a narrow bandwidth comb spectrum, wherein the peak wavelengths of the narrow bandwidth comb spectrum are aligned with the standard wavelengths, and the valley wavelengths of the wide bandwidth comb spectrum are aligned with the standard wavelengths.

In a preferred embodiment, regardless of the spectral shapes corresponding to first output port1 and second output port2, the passband of the narrow bandwidth comb spectrum corresponds to the stopband of the wide bandwidth comb spectrum, and the peak wavelength of the narrow bandwidth comb spectrum is aligned with the valley wavelength of the wide bandwidth comb spectrum, so as to achieve the purpose of separating the main mode spectrum from the side mode spectrum.

When the tunable laser 20 is wavelength-scaled by the wavelength scaling device described above, it is possible that only a portion of the wavelengths may be scaled, while another portion of the wavelengths may need to be scaled in another manner. For example, in other embodiments, the comb filter 11 may be adjusted in steps by switching the center wavelength of the pass band or stop band of the filtered spectrum corresponding to the comb filter 11 to scale all wavelengths that the tunable laser 20 may output. On the other hand, when the wavelength scaling device is used to perform wavelength scaling on the tunable laser 20, it takes time to perform conversion, and an appropriate comb filter 11 is configured, so that it is possible to achieve a better scaling effect.

Example 2:

in order to solve the problem of embodiment 1, this embodiment further provides another wavelength calibration device for a tunable laser, which can complete the calibration operation at one time without performing step by step, and can quickly and conveniently select the adaptive comb filter 11 according to the minimum wavelength channel interval of the tunable laser 20, thereby facilitating industrial production.

In this embodiment, the wavelength scaling apparatus for a tunable laser includes: a system control center 10, a comb filter 11 and an optical power detector 12. The system control center 10 is configured to be connected to a tunable laser 20 to be wavelength-scaled, an input port of the comb filter 11 is configured to be connected to the tunable laser 20 to be wavelength-scaled, an output port of the comb filter 11 is connected to an input end of the optical power detector 12, and an output end of the optical power detector 12 is further connected to the system control center 10.

The comb filter 11 includes an input port com, a first output port1, and a second output port2, the first output port1 and the second output port2 have corresponding filtering spectra that include pass bands and stop bands arranged at preset intervals to filter the laser light emitted by the tunable laser 20, where the preset intervals are wavelength differences between center wavelengths of adjacent pass bands, and the preset intervals are twice wavelength channel intervals of the tunable laser 20.

The number of the comb filters 11 is two, and the comb filters specifically comprise a first comb filter 11-1 and a second comb filter 11-2; the wavelength interval between the extreme wavelength in the filtered spectrum corresponding to the first output port1-1 of the first comb filter 11-1 and the extreme wavelength in the filtered spectrum corresponding to the first output port1-2 of the second comb filter 11-2 is equal to the minimum wavelength channel interval of the tunable laser 20; the wavelength interval between the extreme wavelength in the filtered spectrum corresponding to the second output port2-1 of the first comb filter 11-1 and the extreme wavelength in the filtered spectrum corresponding to the second output port2-2 of the second comb filter 11-2 is equal to the minimum wavelength channel interval of the tunable laser 20.

The first output port1-1 of the first comb filter 11-1 and the first output port1-2 of the second comb filter 11-2 have the same filtering spectrum type; the second output port2-1 of the first comb filter 11-1 and the second output port2-2 of the second comb filter 11-2 have the same filtering spectrum type, and the aforementioned extreme wavelengths refer to peak wavelengths or valley wavelengths. Here, the peak wavelength is the center wavelength corresponding to the pass band, the valley wavelength is the center wavelength corresponding to the stop band, and both the peak wavelength and the valley wavelength are aligned with the standard wavelength.

For example, when the filtered spectrum corresponding to the first output port1-1 of the first comb filter 11-1 and the filtered spectrum corresponding to the first output port1-2 of the second comb filter 11-2 are both narrow-bandwidth comb spectra, the wavelength interval between the peak wavelengths of the output narrow-bandwidth comb spectra of the two is equal to the minimum wavelength channel interval of the tunable laser 20. When the filtered spectrum corresponding to the second output port2-1 of the first comb filter 11-1 and the filtered spectrum corresponding to the second output port2-2 of the second comb filter 11-2 are both wide-bandwidth comb spectra, the wavelength interval between the valley wavelengths of the wide-bandwidth comb spectra output from the two is equal to the minimum wavelength channel interval of the tunable laser 20. According to the design concept, the output spectra of the first comb filter 11-1 and the second comb filter 11-2 are configured to cover continuous output wavelengths, and the specific principle is described in detail below.

Further, for the first comb filter 11-1: the filtered spectrum corresponding to the first output port1-1 of the first comb filter 11-1 is in a complementary relationship with the filtered spectrum corresponding to the second output port2-1 of the first comb filter 11-1. In one embodiment, the filtered spectrum corresponding to the first output port1-1 of the first comb filter 11-1 is a narrow bandwidth comb spectrum, the filtered spectrum corresponding to the second output port2-1 of the first comb filter 11-1 is a wide bandwidth comb spectrum, the peak wavelength of the narrow bandwidth comb spectrum is aligned with the standard wavelength, and the valley wavelength of the wide bandwidth comb spectrum is aligned with the standard wavelength.

In another embodiment, the filtered spectrum corresponding to the first output port1-1 of the first comb filter 11-1 is a wide bandwidth comb spectrum, the filtered spectrum corresponding to the second output port2-1 of the first comb filter 11-1 is a narrow bandwidth comb spectrum, the peak wavelength of the narrow bandwidth comb spectrum is aligned with the standard wavelength, and the valley wavelength of the wide bandwidth comb spectrum is aligned with the standard wavelength;

For the second comb filter 11-2: the filtered spectrum corresponding to the first output port2-1 of the second comb filter 11-2 is in a complementary relationship with the filtered spectrum corresponding to the second output port2-2 of the second comb filter 11-2. In one embodiment, the filtered spectrum corresponding to the first output port2-1 of the second comb filter 11-2 is a narrow bandwidth comb spectrum, the filtered spectrum corresponding to the second output port2-2 of the second comb filter 11-2 is a wide bandwidth comb spectrum, the peak wavelength of the narrow bandwidth comb spectrum is aligned with the standard wavelength, and the valley wavelength of the wide bandwidth comb spectrum is aligned with the standard wavelength.

In another embodiment, the filtered spectrum corresponding to the first output port2-1 of the second comb filter 11-2 is a wide bandwidth comb spectrum, the filtered spectrum corresponding to the second output port2-2 of the second comb filter 11-2 is a narrow bandwidth comb spectrum, the peak wavelength of the narrow bandwidth comb spectrum is aligned with the standard wavelength, and the valley wavelength of the wide bandwidth comb spectrum is aligned with the standard wavelength;

Further, the wavelength scaling device of the tunable laser further includes an optical beam splitter 13; the optical splitter 13 is configured to split the laser light into two paths, where one path of laser light is input to the input port com-1 of the first comb filter 11-1, and the other path of laser light is input to the input port com-2 of the second comb filter 11-2.

In this embodiment, the wavelength scaling apparatus for the tunable laser further includes a driving module 14, an input end of the driving module 14 is connected to the system control center 10, and an output end of the driving module 14 is used for being connected to the tunable laser 20 to be wavelength-scaled. In the wavelength calibration process, the driving module 14 is configured to receive a wavelength control signal output by the system control center 10, and control the tunable laser 20 to output laser matched with the wavelength control signal according to the wavelength control signal.

In a specific application scenario, the system control center 10 includes a setting unit 101, a recording unit 102, and a processing unit 103, where the recording unit 102 is connected to the processing unit 103. The setting unit 101 is connected to the driving module 14, and the recording unit 102 is connected to the optical power detector 12.

The setting unit 101 is configured to generate a wavelength control signal for adjusting the output wavelength of the tunable laser 20 according to an initial value of the wavelength control signal, a scanning range of the wavelength control signal, and a scanning step length, so as to perform a scanning test on the tunable laser 20 according to the wavelength control signal. The setting unit 101 is further configured to set an operating temperature of the tunable laser 20 and an optical power of the output laser.

Here, the process of generating the control signal by the setting unit 101 will be explained by taking the tunable laser 20 as a four-section DBR tunable laser 20 as an example. And fixing the control current of the phase shift area unchanged by adopting a carpet type scanning mode, and sequentially setting the currents of the front grating reflection area and the rear grating reflection area according to the scanning step length to obtain corresponding wavelength control signals until the corresponding current value exceeds the scanning range.

The recording unit 102 is configured to record the optical power value detected by the optical power detector 12, and establish a scan data record table, where the scan data record table includes the wavelength control signal and the optical power value corresponding to the wavelength control signal.

The processing unit 103 is configured to obtain a side mode suppression ratio of the laser corresponding to the wavelength control signal according to the scan data record table, screen out a target side mode suppression ratio of which the side mode suppression ratio is not smaller than a screening threshold, and establish an initial wavelength calibration lookup table according to the target side mode suppression ratio and the wavelength control signal corresponding to the target side mode suppression ratio. Wherein the filtering threshold is set according to the parameters of the comb filter 11.

The processing unit 103 is further configured to control the tunable laser 20 to emit laser according to the initial wavelength calibration lookup table, measure an actual wavelength and an optical power of the laser triggered by the wavelength control signal, and establish a final wavelength calibration lookup table according to the wavelength control signal, the actual wavelength, and the optical power. Specifically, a spectrometer or a wavelength meter may be used to accurately measure the actual wavelength of the laser, and a final wavelength calibration lookup table may be established according to the wavelength control signal and the actual wavelength. For the same wavelength, only the wavelength control signal with the maximum light output power is reserved, so that the wavelength calibration of the tunable laser 20 is completed, and in actual use, the tunable laser 20 can be adjusted to output laser with corresponding wavelength through the final wavelength calibration look-up table.

In the present embodiment, based on different principles, there are at least the following two ways to implement the comb filter 11:

the first method is as follows: based on the implementation of the Fabry-Perot etalon, the reflection end of the Fabry-Perot etalon is used as the wide-bandwidth comb spectrum output port of the comb filter 11, and the transmission end is used as the narrow-bandwidth comb spectrum output port of the comb filter 11. A specific example of the comb filter 11 manufactured based on the fabry-perot etalon is shown in fig. 7a, where the comb filter 11 includes a dual-core fiber collimator 111, a fabry-perot etalon 112, and a single-core fiber collimator 113. The dual-core fiber collimator 111 includes two fibers, one fiber is used as an input port of the comb filter 11, and the other fiber is used as an output port of the wide-bandwidth comb spectrum; the output fiber of the single fiber collimator 113 serves as a narrow bandwidth comb spectrum output port. The light beam incident through the input port of the dual-core fiber collimator 111 forms a reflection spectrum of multi-beam interference on the front surface of the fabry-perot etalon 112, and forms a transmission spectrum of multi-beam interference on the rear surface of the fabry-perot etalon 112, the reflection spectrum is received by the dual-core fiber collimator 111 and coupled into another optical fiber, and the transmission spectrum is received by the single-core fiber collimator 113 to manufacture the three-port comb filter 11.

The cavity length of the Fabry-Perot etalon 112 determines the FSR (free Spectrum) of the transmission and reflection spectra of the Fabry-Perot etalon 112, and the FSR and reflectivity of the cavity surfaces of the Fabry-Perot etalon 112 determine the bandwidth of the transmission spectrum of the Fabry-Perot etalon 112. Therefore, in the actual manufacturing process, the cavity length of the fabry-perot etalon 112 can be determined according to the minimum wavelength channel spacing of the tunable laser 20, and the reflectivity of the cavity surface of the fabry-perot etalon 112 can be determined according to the calibration accuracy of the wavelength of the tunable laser 20.

The second method comprises the following steps: based on the implementation of the up-and-down micro-ring filter, an upload (import) port of the up-and-down micro-ring filter serves as an input port of the comb filter 11, a download (drop) port serves as a narrow-bandwidth comb spectrum output port of the comb filter 11, and a through (through port) port serves as a wide-bandwidth comb spectrum output port of the comb filter 11. Since the up-down type micro-loop filter can be equivalent to the Fabry-Perot etalon, the related characteristics are not described in detail.

For clearly explaining the principle of the present embodiment, as shown in fig. 5a to fig. 6b, the first output port1-1 of the first comb filter 11-1 corresponds to a narrow-bandwidth comb spectrum L1-1, the second output port2-1 of the first comb filter 11-1 corresponds to a wide-bandwidth comb spectrum L2-1; the first output port1-2 of the second comb filter 11-2 corresponds to a filtered spectrum of the narrow-bandwidth comb spectrum L1-2, and the second output port2-2 of the second comb filter 11-2 corresponds to a filtered spectrum of the wide-bandwidth comb spectrum L2-2, for example.

Wherein λ is_i-3、λ_i-2、λ_i-1、λ_i、λ_i+1、λ_i+2、λ_i+3… … are standard wavelengths set according to ITU requirements, adjacent wavelengths differing by the minimum wavelength channel spacing of the tunable laser 20. E.g. λ_i-2And λ_i-1Lambda of_i-1And λ_iLambda of_i+1And λ_i+2All differing by one wavelength channel spacing. In alternative embodiments, the wavelength of the laser light output by the tunable laser 20 may be λ_i-3、λ_i-2、λ_i-1、λ_i、λ_i+2、λ_i+3……。

With respect to the first comb filter 11-1, as can be seen from FIG. 5a, the peak wavelength (λ) of the narrow bandwidth comb spectrum L1-1_i-2、λ_i、λ_i+2… …) and the valley wavelength (λ) of the broad bandwidth comb spectrum L2-1_i-2、λ_i、λ_i+2… …) to be used. The spacing between adjacent peak wavelengths, and the spacing between adjacent valley wavelengths, is equal to 2 times the wavelength channel spacing of the tunable laser 20. The peak wavelength is a center wavelength corresponding to a peak position of the narrow bandwidth comb spectrum L1-1, and the valley wavelength is a center wavelength corresponding to a valley position of the wide bandwidth comb spectrum L2-1.

With respect to the second comb filter 11-2, as can be seen from FIG. 5b, the peak wavelength (λ) of the narrow bandwidth comb spectrum L1-2_i-1、λ_i+1、λ_i+3… …) and wide bandwidth comb lightValley wavelength (λ) of spectrum L2-2_i-1、λ_i+1、λ_i+3… …) to be used. The spacing between adjacent peak wavelengths, and the spacing between adjacent valley wavelengths, is equal to 2 times the wavelength channel spacing of the tunable laser 20. The peak wavelength refers to the center wavelength corresponding to the peak position of the narrow bandwidth comb spectrum L1-2, and the valley wavelength refers to the center wavelength corresponding to the valley position of the wide bandwidth comb spectrum L2-2.

For the first comb filter 11-1 and the second comb filter 11-2, the peak wavelength of the narrow bandwidth comb spectrum L1-1 and the peak wavelength of the narrow bandwidth comb spectrum L1-2 differ by one wavelength channel interval.

As shown in FIG. 6a, the spectrum L3 reflects an output wavelength λ_iThe central wavelength of the main mode (corresponding to the output wavelength lambda of the tunable laser 20)_i) With the peak wavelength λ of the narrow bandwidth comb spectrum L1-1_iAligned, i.e., falling within the passband region of the narrow bandwidth comb spectrum L1-1; the center wavelength of the left side mode is about lambda_i-1The center wavelength of the right mode is about lambda_i+1I.e., the band stop region falling within the narrow bandwidth comb spectrum L1-1. Under the effect of narrow-bandwidth comb spectrum L1-1, the filtered spectrum corresponding to first output port1-1 of first comb filter 11-1 can filter out the side-mode spectrum, while allowing the main-mode spectrum to pass through.

The center wavelength of the master mode (corresponding to the output wavelength λ of the tunable laser 20)_i) And the valley wavelength lambda of the wide bandwidth comb spectrum L2-1_iAligned, i.e., falling within the stop band region of wide bandwidth comb spectrum L2-1; the center wavelength of the left side mode is about lambda_i-1The center wavelength of the right mode is about lambda_i+1I.e., the passband region falling within wide bandwidth comb spectrum L2-1. Under the effect of wide bandwidth comb spectrum L2-1, the filtered spectrum corresponding to second output port2-1 of first comb filter 11-1 can filter out the main mode spectrum and allow the side mode spectrum to pass through.

Therefore, the purpose of separating the main mode spectrum and the side mode spectrum is achieved, the main mode spectrum power and the side mode spectrum power are correspondingly detected, and the side mode suppression ratio of the laser is obtained.

In practical application, when the tunable laser 20 outputs a wavelength λ_iWhen the laser light differs by 2n (n is a positive integer) wavelength channel intervals, for example, the wavelength of the laser light is λ_i-2、λ_i+2Or λ_i+4In all cases, the main mode spectrum and the side mode spectrum can be separated by the first comb filter 11-1.

As shown in FIG. 6b, the spectrum L3 reflects an output wavelength λ_i+1The central wavelength of the main mode (corresponding to the output wavelength lambda of the tunable laser 20)_i+1) With the peak wavelength λ of the narrow bandwidth comb spectrum L1-2_i+1Aligned, i.e., falling in the passband region of narrow bandwidth comb spectrum L1-2; the center wavelength of the left side mode is about lambda_iThe center wavelength of the right mode is about lambda_i+2I.e., the blocker region that falls within the narrow bandwidth comb spectrum L1-2. Under the effect of narrow-bandwidth comb spectrum L1-2, the filtered spectrum corresponding to first output port1-2 of second comb filter 11-2 can filter out the side-mode spectrum, while allowing the main-mode spectrum to pass through.

The center wavelength of the master mode (corresponding to the output wavelength λ of the tunable laser 20)_i+1) And the valley wavelength lambda of the wide bandwidth comb spectrum L2-2_i+1Aligned, i.e., falling in the blocker region of wide bandwidth comb spectrum L2-2; the center wavelength of the left side mode is about lambda_iThe center wavelength of the right mode is about lambda_i+2I.e., the passband region falling within wide bandwidth comb spectrum L2-2. Under the effect of wide bandwidth comb spectrum L2-2, the filtered spectrum corresponding to second output port2-2 of second comb filter 11-2 can filter out the main mode spectrum and allow the side mode spectrum to pass through.

In practical application, when the tunable laser 20 outputs a wavelength λ_i+1When the laser light differs by 2n (n is a positive integer) wavelength channel intervals, for example, the wavelength of the laser light is λ_i-3、λ_i-1Or λ_i+3When the situation is equal, the second step can be passedComb filter 11-2 separates the main mode spectrum from the side mode spectrum.

In this embodiment, when the center wavelength of the main mode output by the tunable laser 20 coincides with a certain peak wavelength of the comb spectrum with a narrow bandwidth corresponding to the first comb filter 11-1 or the second comb filter 11-2, the side mode of the output spectrum of the tunable laser 20 is just in the passband region of the comb spectrum with a wide bandwidth corresponding to the first comb filter 11-1 or the second comb filter 11-2. The first output port corresponding to the first comb filter 11-1 or the second comb filter 11-2 outputs the optical power sample value P₁The main mode spectral power of the tunable laser 20 can be reflected; a second output port corresponding to the first comb filter 11-1 or the second comb filter 11-2 for outputting the optical power sample value P₂The optical power of the side modes of the spectrum output by the tunable laser 20 may be reflected. Thus, the ratio of the sampled primary mode spectral power value P1 to the sampled side mode spectral power value P2 (P)₁/P₂) Namely the side mode suppression ratio SMSR of the laser.

When the center wavelength of the main mode coincides with the standard wavelength (ITU wavelength), that is, coincides with a certain peak wavelength of the first comb filter 11-1 or the second comb filter 11-2, the main mode spectral power P₁And the side mode suppression ratio SMSR can take a maximum value. Therefore, the size of the side-mode suppression ratio SMSR can be used as a criterion for determining whether the output wavelength of the tunable laser 20 is aligned with the standard wavelength, i.e., a criterion for wavelength scaling.

In other application scenarios, when the first output port1-1 of the first comb filter 11-1 corresponds to a wide bandwidth comb spectrum, the second output port2-1 of the first comb filter 11-1 corresponds to a narrow bandwidth comb spectrum; similar principles are realized when the corresponding filtered spectrum of the first output port1-2 of the second comb filter 11-2 is a wide bandwidth comb spectrum, and the corresponding filtered spectrum of the second output port2-2 of the second comb filter 11-2 is a narrow bandwidth comb spectrum, which is not described herein again.

It should be noted that, because the first comb filter 11-1 or the second comb filter 11-2 has the characteristics of a wide bandwidth comb spectrum having a pass bandwidth and a flat top, in an actual calibration process, there is no strict requirement on the wavelength interval between the main mode and the side mode of the tunable laser 20, and the wavelength interval between the main mode and the side mode is approximately equal to the minimum wavelength channel interval of the tunable laser 20, that is, the wavelength calibration apparatus of this embodiment may be used to perform wavelength calibration on the tunable laser 20.

It should be noted that the peak wavelength, the valley wavelength, the interval between adjacent peak wavelengths, and the interval between adjacent valley wavelengths of the comb filter 11 are adjustable, so that the corresponding comb filter 11 is configured according to the output wavelength of the tunable laser 20 and the minimum wavelength channel interval, so as to perform wavelength calibration on tunable lasers 20 of different types, so that the applicability of the comb filter 11 is wider.

Example 3:

corresponding to the foregoing

embodiments

1 and 2, this embodiment further provides a wavelength calibration method for a tunable laser, and the wavelength calibration device of the foregoing embodiments is controlled by the wavelength calibration method to complete wavelength calibration of the tunable laser.

With reference to fig. 2 to 4 and fig. 8 to 9, the wavelength calibration method for the tunable laser of the present embodiment includes the following steps:

step 80: and performing scanning test on the tunable laser based on the wavelength control signal, and driving the tunable laser to output laser matched with the wavelength control signal, wherein the spectrum corresponding to the laser comprises a main mode spectrum and a side mode spectrum.

In this embodiment, a setting unit of a system control center generates a wavelength control signal for adjusting an output wavelength of the tunable laser according to an initial value of a wavelength control signal, a scanning range of the wavelength control signal, and a scanning step length, and performs a scanning test on the tunable laser according to the wavelength control signal.

Here, the process of generating the control signal by the setting unit will be explained by taking the tunable laser as a four-segment DBR tunable laser as an example. And fixing the control current of the phase shift area unchanged by adopting a carpet type scanning mode, and sequentially setting the currents of the front grating reflection area and the rear grating reflection area according to the scanning step length to obtain corresponding wavelength control signals until the corresponding current value exceeds the scanning range.

And a processing unit of the system control center performs scanning test on the tunable laser according to the wavelength control signal, and drives the tunable laser to output laser matched with the wavelength control signal, wherein the spectrum corresponding to the laser comprises a main mode spectrum and a side mode spectrum.

Step 81: the first output port of the comb filter outputs laser for filtering side mode spectrum, and the second output port of the comb filter outputs laser for filtering main mode spectrum, wherein the first output port of the comb filter and the second output port of the comb filter correspond to filtering spectrums which respectively comprise a pass band and a stop band which are arranged according to a preset interval, and the preset interval is equal to the multiplication of the wavelength channel interval of the tunable laser by a preset multiple.

In this embodiment, a first output port of the comb filter outputs laser for filtering a side mode spectrum, and a second output port of the comb filter outputs laser for filtering a main mode spectrum, where the first output port and the second output port correspond to filter spectrums, each of which includes a pass band and a stop band arranged at a preset interval, the preset interval is a wavelength difference between center wavelengths of adjacent pass bands, and the preset interval is equal to a wavelength channel interval of the tunable laser multiplied by a preset multiple.

In a preferred embodiment, the number of the comb filters is two, specifically, a first comb filter and a second comb filter; the wavelength interval between the extreme wavelength of the filtered spectrum corresponding to the first output port of the first comb filter and the extreme wavelength of the filtered spectrum corresponding to the first output port of the second comb filter is equal to the minimum wavelength channel interval of the tunable laser; the wavelength interval between the extreme wavelength of the filtered spectrum corresponding to the second output port of the first comb filter and the extreme wavelength of the filtered spectrum corresponding to the second output port of the second comb filter is equal to the minimum wavelength channel interval of the tunable laser. The first output port of the first comb filter and the first output port of the second comb filter have the same corresponding filtering spectrum type; the second output port of the first comb filter and the second output port of the second comb filter have the same corresponding filtering spectrum type, and the extreme wavelength refers to a peak wavelength or a valley wavelength. Here, the peak wavelength is a center wavelength corresponding to the pass band, the valley wavelength is a center corresponding to the stop band, and both the peak wavelength and the valley wavelength are aligned with the standard wavelength.

In this embodiment, the first output port of the comb filter outputs the laser with the side mode spectrum filtered, and the second output port of the comb filter outputs the laser with the main mode spectrum filtered, so as to separate the main mode spectrum and the side mode spectrum of the laser, so as to obtain the side mode suppression ratio of the laser.

Step 82: the main mode spectral power of the laser light output through the first output port of the comb filter is detected, and the side mode spectral power of the laser light output through the second output port of the comb filter is detected.

In this embodiment, an optical power detector is used to output the main mode spectral power of the laser light through the first output port of the comb filter and the side mode spectral power of the laser light through the second output port of the comb filter. In a practical application scenario, the optical power detector may be a single device including a plurality of independent sub-detectors, so as to detect the power of the laser output by the output port correspondingly. Or, the number of the optical power detectors is multiple, and an optical power detection array formed by the multiple optical power detectors is adopted to detect the power of the laser output by the corresponding output port.

Step 83: and acquiring the main mode spectral power and the side mode spectral power to obtain a side mode rejection ratio.

In practical application, when the center wavelength of the main mode output by the tunable laser is equal to the center wavelength of the first comb filter orWhen a certain peak wavelength of the narrow-bandwidth comb spectrum of the second comb filter coincides, the side mode of the tunable laser output spectrum is just in the passband region of the wide-bandwidth comb spectrum of the first comb filter or the second comb filter. A first output port of the first comb filter or the second comb filter outputs a light power sampling value P₁The main mode spectral power of the tunable laser can be reflected; the second output port of the first comb filter or the second comb filter outputs the optical power sampling value P₂The optical power of the side modes of the output spectrum of the tunable laser may be reflected. Thus, the ratio of the sampled primary mode spectral power value P1 to the sampled side mode spectral power value P2 (P)₁/P₂) Namely the side mode suppression ratio SMSR of the laser.

Step 84: and establishing a wavelength calibration lookup table after determining that the output wavelength of the tunable laser is aligned with the standard wavelength according to the side mode suppression ratio.

The main mode spectral power P when the center wavelength of the main mode coincides with the standard wavelength (ITU wavelength), i.e. with a certain peak wavelength of the first comb filter or the second comb filter₁And the side mode suppression ratio SMSR can take a maximum value. Therefore, the size of the side-mode suppression ratio SMSR can be used as a judgment criterion for judging whether the output wavelength of the tunable laser is aligned with the standard wavelength, i.e. wavelength calibration.

Referring to fig. 9, step 84 includes the steps of:

step 841: and judging whether the side mode suppression ratio is not less than a screening threshold value.

In this embodiment, it is determined whether the side mode suppression ratio is not less than the screening threshold. If the side-mode suppression ratio is not less than the screening threshold, go to step 842; if the side-mode suppression ratio is less than the screening threshold, then step 843 is performed.

Step 842: if the side mode suppression ratio is not smaller than the screening threshold, reserving the wavelength control signal corresponding to the side mode suppression ratio, and establishing an initial calibration lookup table according to the side mode suppression ratio and the wavelength control signal corresponding to the side mode suppression ratio.

In this embodiment, if the side mode suppression ratio is not less than the screening threshold, the wavelength control signal corresponding to the side mode suppression ratio is retained, and the recording unit of the system control center records the optical power value detected by the optical power detector and establishes a scan data recording table, where the scan data recording table includes the wavelength control signal and the optical power value corresponding to the wavelength control signal.

Step 843: and if the side mode suppression ratio is smaller than the screening threshold value, rejecting the corresponding wavelength control signal corresponding to the side mode suppression ratio.

Step 844: and controlling the tunable laser to emit laser according to the initial wavelength calibration lookup table.

In this embodiment, the processing unit of the system control center queries the wavelength control signal according to the initial wavelength calibration lookup table, and then controls the tunable laser to emit laser according to the wavelength control signal.

Step 845: and measuring the actual wavelength and the optical power of the laser triggered by the wavelength control signal.

In this embodiment, a spectrometer or a wavelength meter may be used to accurately measure the actual wavelength of the laser and measure the optical power of the laser.

Step 846: and establishing a final wavelength calibration lookup table according to the wavelength control signal, the actual wavelength and the optical power.

In this embodiment, only the wavelength control signal with the maximum optical power is reserved for the same wavelength. Then, the recording unit of the system control center records the wavelength control signal and the actual wavelength to establish a final wavelength calibration lookup table. And finally, wavelength calibration of the tunable laser is completed, and in actual use, the tunable laser can be adjusted to output laser with corresponding wavelength through a final wavelength calibration lookup table.

For the principle of wavelength calibration, please refer to fig. 5a to fig. 6b, and the related text explanation in embodiment 1, which are not repeated herein.

In this embodiment, through steps 80 to 81, when the tunable laser is subjected to the scan test, the operation of repeatedly switching the center wavelength of the filter is avoided, so that a large amount of test time can be saved, meanwhile, the misoperation can be avoided, and the test accuracy is improved.

In this embodiment, through steps 841 to 843, whether the output wavelength of the tunable laser is aligned with the standard wavelength is preliminarily determined, so that a large amount of useless test data can be eliminated, the data amount of the subsequent wavelength calibration test is reduced, and the test efficiency is improved. Moreover, the comb filter has low cost and easy manufacture, and is suitable for industrial production.

It should be noted that, for the information interaction, execution process and other contents between the modules and units in the apparatus and system, the specific contents may refer to the description in the embodiment of the method of the present invention because the same concept is used as the embodiment of the processing method of the present invention, and are not described herein again.

Those of ordinary skill in the art will appreciate that all or part of the steps of the various methods of the embodiments may be implemented by associated hardware as instructed by a program, which may be stored on a computer-readable storage medium, which may include: a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and the like.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A wavelength scaling apparatus for a tunable laser, the apparatus comprising: the system comprises a system control center, a comb filter and an optical power detector;

the preset interval is twice the wavelength channel interval of the tunable laser, and the comb filter specifically comprises a first comb filter and a second comb filter; the wavelength interval between the extreme value wavelength in the filtering spectrum corresponding to the first output port of the first comb filter and the extreme value wavelength in the filtering spectrum corresponding to the first output port of the second comb filter is equal to the wavelength channel interval of the tunable laser; the wavelength interval between the extreme value wavelength in the filtering spectrum corresponding to the second output port of the first comb filter and the extreme value wavelength in the filtering spectrum corresponding to the second output port of the second comb filter is equal to the wavelength channel interval of the tunable laser;

2. The wavelength scaling apparatus of a tunable laser of claim 1, further comprising an optical beam splitter;

3. The wavelength scaling apparatus of a tunable laser according to claim 1 or 2, wherein a filtered spectrum corresponding to the first output port of the first comb filter is in a complementary relationship with a filtered spectrum corresponding to the second output port of the first comb filter;

4. The wavelength scaling apparatus of a tunable laser according to claim 1 or 2, wherein the filtered spectrum corresponding to the first output port of the second comb filter is in a complementary relationship with the filtered spectrum corresponding to the second output port of the second comb filter;

5. The wavelength scaling apparatus of a tunable laser according to claim 1 or 2, wherein the system control center comprises a setting unit, a recording unit and a processing unit;

6. The apparatus of claim 5, wherein the system control center is further configured to control the tunable laser to emit laser light according to the initial wavelength calibration lookup table, measure an actual wavelength and an optical power of the laser light triggered by the wavelength control signal, and establish a final wavelength calibration lookup table according to the wavelength control signal, the actual wavelength, and the optical power.

7. A method for wavelength scaling of a tunable laser, the method comprising:

the first output port of the comb filter outputs laser for filtering side mode spectrum, and the second output port of the comb filter outputs laser for filtering main mode spectrum, wherein the first output port of the comb filter and the second output port of the comb filter correspond to filtering spectrums which respectively comprise a pass band and a stop band which are arranged according to a preset interval, and the preset interval is equal to the multiplication of the wavelength channel interval of the tunable laser by a preset multiple; the preset interval is twice the wavelength channel interval of the tunable laser, and the comb filter specifically comprises a first comb filter and a second comb filter; the wavelength interval between the extreme value wavelength in the filtering spectrum corresponding to the first output port of the first comb filter and the extreme value wavelength in the filtering spectrum corresponding to the first output port of the second comb filter is equal to the wavelength channel interval of the tunable laser; the wavelength interval between the extreme value wavelength in the filtering spectrum corresponding to the second output port of the first comb filter and the extreme value wavelength in the filtering spectrum corresponding to the second output port of the second comb filter is equal to the wavelength channel interval of the tunable laser;

8. The method of claim 7, wherein the step of building a wavelength scaling look-up table after determining that the output wavelength of the tunable laser is aligned with a standard wavelength according to the side-mode suppression ratio comprises:

9. The method of claim 8, wherein the step of building a wavelength scaling look-up table after determining that the output wavelength of the tunable laser is aligned with a standard wavelength according to the side-mode suppression ratio comprises: