CN113406744A

CN113406744A - Fourier waveguide light splitting chip

Info

Publication number: CN113406744A
Application number: CN202110721901.XA
Authority: CN
Inventors: 王伟平; 于佳睿; 操俊; 胡小燕; 曹静; 郭于鹤洋; 王子欣
Original assignee: CETC Information Science Research Institute
Current assignee: CETC Information Science Research Institute
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2021-09-17
Anticipated expiration: 2041-06-28
Also published as: CN113406744B

Abstract

The application provides a Fourier waveguide light splitting chip which comprises a first coupler, a light splitting unit and a detector, wherein the first coupler is a polarization insensitive coupler and is used for receiving input light, and the input light comprises light in a plurality of polarization directions; the light splitting unit is connected with the first coupler and is used for splitting input light; the detector is connected with the light splitting unit and used for converting the split input light into corresponding electric signals. The utility model provides a Fourier type waveguide spectral chip is through introducing into chip level spectrum spectrometer with the insensitive first coupler of polarization, can couple a plurality of polarization direction's of simultaneous input light, and the energy utilization who has guaranteed the light source is higher, has solved better among the prior art chip level spectrum analyzer and has adopted polarization sensitive device, needs the input of fixed polarization state, leads to the lower problem of light energy utilization.

Description

Fourier waveguide light splitting chip

Technical Field

The application relates to the field of spectral analysis, in particular to a Fourier waveguide light splitting chip.

Background

The spectrum analysis technology is an important optical detection perception means, has the advantages of non-contact, nondestructive and real-time detection, and can be widely applied to a plurality of fields such as food substance component detection, gas detection, biomedical application and the like. The traditional spectrum detection technology is based on discrete optical-mechanical components, the instrument is large in size, although the precision is high, the manufacturing cost is high (hundreds of thousands to millions), the flexibility and the stability are poor, and the application range of the spectrometer is limited.

The silicon optical integration technology provides an effective solution for the miniaturization of a spectrometer, the existing common chip-level spectrum spectrometer is mainly based on a dispersion element, such as a chip-level spectrum analyzer made of two most typical dispersion plane integrated optical elements, namely a silicon-based etched diffraction grating and a silicon-based array waveguide grating, the research is mature, but if the higher resolution is to be realized, the number of channels of the spectrum needs to be increased, the size of the device needs to be increased, the larger phase error can be brought, the signal-to-noise ratio is reduced, and the dynamic range of the system is lower. In addition, each channel needs a detector for detection, and the system structure is complex.

The Fourier transform type spectrum analyzer has the advantage of multiple channels, and can overcome the contradiction between the signal-to-noise ratio and the spectral resolution. The chip-level Fourier transform spectrometer mainly realizes the change of optical path difference based on the arrangement of thermo-optic/electro-optic or structure. Currently, a common fourier transform chip-scale optical spectrum analyzer is mainly a spatially heterodyne chip spectrometer based on an MZI (Mach-Zehnder interferometer) array or an MZI chip spectrometer based on thermo-optic phase modulation. The optical path difference of the MZI array type spectrometer is in a linear relation with the number of the MZIs, and the optical path difference of the thermo-optic phase modulation type spectrometer is in direct proportion with the arm length and the temperature change range of the MZIs. To achieve higher spectral resolution, the MZI array size and the arm length of the thermo-optic MZI still need to be increased, which in turn leads to an increase in the size of the whole chip.

In order to meet the requirements of high resolution and high integration in practical use, a more compact spectral splitting structure with large optical path difference needs to be designed. Meanwhile, because the waveguide has a strong birefringence effect, the chip-level spectrum analyzer is generally a polarization sensitive device, needs a fixed polarization state to be input, and has a low light energy utilization rate.

The above information disclosed in this background section is only for enhancement of understanding of the background of the technology described herein and, therefore, certain information may be included in the background that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

Disclosure of Invention

The main object of this application is to provide a Fourier type waveguide spectral chip to solve the lower problem of the light energy utilization ratio of chip level spectral analyser among the prior art.

In order to achieve the above object, according to an aspect of the present application, there is provided a fourier-type waveguide optical splitting chip, including a first coupler, an optical splitting unit, and a detector, where the first coupler is a polarization insensitive coupler, and the first coupler is configured to receive input light, and the input light includes light with multiple polarization directions; the light splitting unit is connected with the first coupler and is used for splitting the input light; the detector is connected with the light splitting unit and used for converting the input light after light splitting into corresponding electric signals.

Optionally, the optical splitting unit includes a first beam splitter, a first rotator, an MZI spectral splitting structure based on an optical switch, a second rotator, and a first beam combiner, where the first beam splitter is connected to the first coupler, the first beam splitter is configured to split the input light into first polarized light and second polarized light, and a polarization direction of the first polarized light is perpendicular to a polarization direction of the second polarized light; the first rotator is connected with the first beam splitter, and the first rotator is used for converting the first polarized light into the second polarized light or converting the second polarized light into the first polarized light; the MZI spectrum optical splitting structure based on the optical switch is connected to the first rotator and the first beam splitter, and is configured to split the received first polarized light to obtain a third polarized light, or split the received second polarized light to obtain a fourth polarized light, and includes two output interfaces, and is further configured to output the third polarized light through the two output interfaces, or output the fourth polarized light through the two output interfaces; the second rotator is connected to one of the two output interfaces, and the second rotator is configured to convert the third polarized light into the fourth polarized light or convert the fourth polarized light into the third polarized light; the first beam combiner is connected with the other of the two output interfaces and the second rotator respectively, and the first beam combiner is used for combining received light.

Alternatively, the first polarized light and the third polarized light are both Transverse electric waves (TE waves), and the second polarized light and the fourth polarized light are both Transverse magnetic waves (TM waves).

Optionally, the MZI optical spectrum splitting structure based on the optical switch includes two sub-splitting structures, an input end of one of the sub-splitting structures is connected to one of the first rotator and the first beam splitter, an input end of the other sub-splitting structure is connected to the other of the first rotator and the first beam splitter, and an output end of the sub-splitting structure is the output interface.

Optionally, the optical switch-based MZI optical spectrum splitting structure includes a second beam splitter, a plurality of cascaded optical switches, a plurality of second couplers, and a second beam combiner, where an input end of the second beam splitter is an input end of the sub-splitting structure; the cascade optical switch comprises N sub optical switches and N unequal-arm waveguides, wherein the input end of the first sub optical switch is connected with the output end of the second beam splitter, the Mth sub optical switch is connected with the M +1 th sub optical switch through the unequal-arm waveguides, and M is more than or equal to 1 and is less than N; the input end of the second coupler is connected with the output end of the Nth sub-optical switch through the Nth non-equal-arm waveguide; the input end of the second beam combiner is connected with the output ends of the plurality of second couplers, and the output end of the second beam combiner is the output end of the sub-light splitting structure.

Optionally, the sub optical switch includes a third coupler, a first phase shifter, a second phase shifter, and a fourth coupler, where an input terminal of the third coupler is an input terminal of the sub optical switch; the first end of the first phase shifter and the first end of the second phase shifter are respectively connected with the output end of the third coupler; an input end of the fourth coupler is connected to the second end of the first phase shifter and the second end of the second phase shifter, respectively, and an output end of the fourth coupler is an output end of the sub-optical switch.

Optionally, the third coupler and the fourth coupler are each independently selected from one or more of a silicon-based directional coupler, a silicon-based Y-type coupler, and a multimode interference coupler.

Optionally, the second beam splitter comprises a fifth coupler and the second beam combiner comprises a sixth coupler.

Optionally, the sub-optical switches are electro-optical switches or thermo-optical switches.

Optionally, the first coupler comprises a one-dimensional non-uniform period grating coupler.

Optionally, the first coupler, the light splitting unit and the detector are integrated by using a Complementary Metal Oxide Semiconductor (CMOS) process.

Use the technical scheme of this application, Fourier type waveguide beam split chip, including the insensitive first coupler of polarization, beam split unit and the detector that connect gradually, first coupler is used for receiving input light, input light includes the light of a plurality of polarization directions, beam split unit is used for right input light divides the light, the detector is used for with the beam split after input light converts the signal of telecommunication into. The utility model provides a Fourier type waveguide spectral chip is through insensitive with the polarization during chip level spectrum spectrometer is introduced to first coupler, the input light of a plurality of polarization directions of can coupling simultaneously, and the energy utilization who has guaranteed the light source is higher, has solved better among the prior art chip level spectrum analyzer and has adopted polarization sensitive device, needs the input of fixed polarization state, leads to the lower problem of light energy utilization.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application. In the drawings:

fig. 1 shows a schematic structural diagram of a fourier-type waveguide optical splitter chip according to an embodiment of the present application;

FIG. 2 shows a schematic diagram of a sub-spectroscopic structure according to an embodiment of the present application;

FIG. 3 shows a design layout diagram of a sub-spectroscopic structure according to an embodiment of the present application;

FIG. 4 shows a schematic diagram of a first coupler according to an embodiment of the present application;

FIG. 5 shows a simulation result diagram of a first coupler according to an embodiment of the application;

FIG. 6 is a schematic diagram showing a spectral distribution of a signal under test for Fourier waveguide optical splitter chip simulation according to an embodiment of the application;

FIG. 7 shows a graph of a simulated input signal's corresponding transmittance spectra at different arm length differences and different wavelengths according to an embodiment of the application;

fig. 8 is a diagram illustrating simulation results of a fourier-type waveguide optical splitter chip according to an embodiment of the present application.

Wherein the figures include the following reference numerals:

10. a first coupler; 20. a detector; 100. a first beam splitter; 101. a first rotator; 102. MZI spectrum light splitting structure based on optical switch; 103. a second rotator; 104. a first combiner; 105. an output interface; 106. a sub-spectroscopic structure; 200. a second beam splitter; 201. a cascaded optical switch; 202. a second coupler; 203. a second combiner; 204. a sub-optical switch; 205. an unequal-arm waveguide; 206. a heater; 300. a third coupler; 301. a first phase shifter; 302. a second phase shifter; 303. a fourth coupler.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Also, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element or "connected" to the other element through a third element.

As described in the background art, the optical energy utilization rate of the chip-scale spectrum analyzer in the prior art is low, and in order to solve the above problems, the present application provides a fourier waveguide spectroscopy chip.

According to an exemplary embodiment of the present application, there is provided a fourier-type waveguide optical splitting chip, as shown in fig. 1, the fourier-type waveguide optical splitting chip includes a first coupler 10, an optical splitting unit, and a detector 20, wherein the first coupler 10 is a polarization-insensitive coupler, the first coupler 10 is configured to receive input light, and the input light includes light with multiple polarization directions; the optical splitting unit is connected to the first coupler 10, and the optical splitting unit is configured to split the input light; the detector 20 is connected to the light splitting unit, and the detector 20 is configured to convert the split input light into a corresponding electrical signal.

The fourier waveguide optical splitting chip comprises a polarization-insensitive first coupler, an optical splitting unit and a detector which are connected in sequence, wherein the first coupler is used for receiving input light, the input light comprises light in a plurality of polarization directions, the optical splitting unit is used for splitting the input light, and the detector is used for converting the input light after being split into an electric signal. The utility model provides an above-mentioned Fourier type waveguide spectral chip introduces chip level spectrum spectrometer through the above-mentioned first coupler insensitive with polarization, can a plurality of polarization direction's of simultaneous coupling input light, has guaranteed that the energy utilization of light source is higher, has solved chip level spectrum analyzer among the prior art better and has adopted polarization sensitive device, needs fixed polarization state input, leads to the lower problem of light energy utilization.

In a specific embodiment of the present application, as shown in fig. 1, the optical splitting unit includes a first beam splitter 100, a first rotator 101, an MZI spectral splitting structure 102 based on an optical switch, a second rotator 103, and a first beam combiner 104, where the first beam splitter 100 is connected to the first coupler 10, the first beam splitter 100 is configured to split the input light into a first polarized light and a second polarized light, and a polarization direction of the first polarized light is perpendicular to a polarization direction of the second polarized light; the first rotator 101 is connected to the first beam splitter 100, and the first rotator 101 is configured to convert the first polarized light into the second polarized light or convert the second polarized light into the first polarized light; the MZI spectral splitting structure 102 based on an optical switch is connected to the first rotator 101 and the first beam splitter 100, the MZI spectrum splitting structure 102 is configured to split the received first polarized light to obtain a third polarized light, or split the received second polarized light to obtain a fourth polarized light, wherein the polarization direction of the third polarized light is the same as the polarization direction of the first polarized light, the polarization direction of the second polarized light is the same as the polarization direction of the fourth polarized light, the optical switch-based MZI spectral splitting structure 102 includes two output interfaces 105, the optical switch-based MZI spectral splitting structure 102 is further configured to output the third polarized light through two of the output interfaces 105, or output the fourth polarized light through two of the output interfaces 105; the second rotator 103 is connected to one of the two output interfaces 105, and the second rotator 103 is configured to convert the third polarized light into the fourth polarized light or convert the fourth polarized light into the third polarized light; the first beam combiner 104 is connected to the other of the two output interfaces 105 and the second rotator 103, and the first beam combiner 104 combines the received light. The light splitting unit can perform interference light splitting on light rays in different polarization directions through the first beam splitter, the first rotator, the MZI spectrum light splitting structure based on the optical switch, the second rotator and the first beam combiner, so that the high energy utilization rate of a light source is further ensured.

The optical splitting unit in the above embodiment has two types, a first type, where the first beam splitter is configured to split the input light into a first polarized light and a second polarized light that are perpendicular to each other, the first rotator is configured to convert the first polarized light into the second polarized light, and the MZI spectrum optical splitting structure based on the optical switch is configured to receive the second polarized light output by the first beam splitter and the first rotator, split the received second polarized light to obtain the fourth polarized light, split all the fourth polarized light into two parts, and output the two parts through the two output interfaces; the second rotator is configured to convert the fourth polarized light output by one of the two output interfaces into the third polarized light; the first beam combiner is configured to combine the fourth polarized light output by the other of the output interfaces and the third polarized light output by the second rotator. In a second case, the first beam splitter is configured to split the input light into a first polarized light and a second polarized light which are perpendicular to each other, the first rotator is configured to convert the second polarized light into the first polarized light, and the MZI spectral splitting structure based on the optical switch is configured to receive the first polarized light output by the first beam splitter and the first rotator, split the received first polarized light to obtain the third polarized light, split all the third polarized light into two parts, and output the two parts through the two output interfaces; the second rotator is configured to convert the third polarized light output by one of the two output interfaces into the fourth polarized light; the first beam combiner is configured to combine the third polarized light output by the other of the output interfaces and the fourth polarized light output by the second rotator.

In practical applications, the first polarized light is a transverse electric wave (TE wave), the second polarized light is a transverse magnetic wave (TM wave), that is, the first polarized light is a TE mode light, and the second polarized light is a TM mode light.

In another specific embodiment of the present application, the MZI optical spectrum splitting structure based on an optical switch includes two sub-splitting structures, wherein an input end of one of the sub-splitting structures is connected to one of the first rotator and the first beam splitter, an input end of the other of the sub-splitting structures is connected to the other of the first rotator and the first beam splitter, and an output end of the sub-splitting structure is the output interface. Of course, the MZI optical spectrum splitting structure based on the optical switch is not limited to the two sub-splitting structures, and may further include a plurality of sub-splitting structures.

In order to ensure the balance between devices and optical paths in the fourier waveguide optical splitting chip, in a more specific embodiment of the present application, as shown in fig. 1, the MZI spectrum optical splitting structure based on an optical switch includes two sub-optical splitting structures 106, wherein an input end of one of the sub-optical splitting structures 106 is connected to the first rotator 101, which is connected to the first beam combiner 104 through the corresponding output interface 105; the input end of the other sub-beam splitting structure 106 is connected to the first beam splitter 100, and is connected to the second rotator 103 through the corresponding output interface 105. Of course, in an actual application process, the connection relationship of the sub-spectroscopic structures is not limited to the connection relationship described above, and a person skilled in the art can design the sub-spectroscopic structures according to actual situations.

In practical applications, the first beam splitter is a polarization beam splitter, the first rotator is a first polarization rotator, the second rotator is a second polarization rotator, and the first beam combiner is a polarization beam combiner.

In order to further ensure that the MZI spectral splitting structure based on the optical switch has a good interference splitting effect and a high spectral resolution, according to another specific embodiment of the present application, as shown in fig. 2, the sub-splitting structure 106 includes a second beam splitter 200, a plurality of cascaded optical switches 201, a plurality of second couplers 202, and a second beam combiner 203, where an input end of the second beam splitter 200 is an input end of the sub-splitting structure 106; the cascaded optical switch 201 includes N sub-optical switches 204 and N unequal-arm waveguides 205, where an input end of a first sub-optical switch is connected to an output end of the second beam splitter 200, an mth sub-optical switch and an M +1 th sub-optical switch are connected through the unequal-arm waveguides 205, and M is greater than or equal to 1 and less than N; the input end of the second coupler 202 is connected to the output end of the nth sub optical switch through an nth non-equal arm waveguide; the input end of the second beam combiner 203 is connected to the output ends of the plurality of second couplers 202, and the output end of the second beam combiner 203 is the output end of the sub-beam splitting structure 106. The sub-beam splitting structure adopts a plurality of cascade optical switches and different arm length combinations, and MZI waveguide beam splitting optical paths with different optical path differences can be constructed by adjusting the switch states of the plurality of optical switches to perform high-resolution interference beam splitting on wide-spectrum incident light. Meanwhile, the spectral resolution of the Fourier waveguide optical splitting chip is exponentially improved along with the increase of the number of the cascaded optical switches, and on the premise that the size of the Fourier waveguide optical splitting chip is not increased, the high resolution of the chip and the good expandability of the chip can be ensured.

By changing the switch state of each sub-optical switch in the module, MZI spectrum light splitting structures with different arm length differences can be combined. In a specific embodiment, referring to fig. 2, the sub-splitting structure 106 is composed of two cascaded optical switches 201, each cascaded optical switch is an arm of the sub-splitting structure, each arm of the sub-splitting structure 106 is composed of N cascaded sub-optical switches 204, and the sub-optical switches 204 are connected to unequal arm waveguides 205 with different lengths. The length difference of the non-equal arm waveguide is exponential times of 2 delta L, namely delta L, 2 delta L, 4 delta L, 8 delta L and 16 delta L. If the arm lengths of the upper and lower arms of the sub spectroscopic structure 106 are equal, the optical path difference between the upper and lower arms is 0. By switching the switching state of the sub-optical switch 204, the optical path difference between the upper and lower arms can be changed from 0 to (2)^2N-1)n_gΔ L, each step is n_gΔ L, wherein n_gIs the index of refraction of the waveguide group. The number of spectral channels and the resolution of the sub-spectroscopic structure are respectively as follows:

J＝2^2N

wherein J is the number of spectral channels; 2N is the total number of the sub-optical switches; δ λ is the spectral resolution; λ is the center wavelength; n is_gIs the group index of the waveguide; Δ L is the step value of the wavelength difference. The spectral resolution increases exponentially as the number of sub-optical switches increases. In a specific embodiment, referring to fig. 3, a design layout of the sub-spectroscopic structure is shown, a sub-spectroscopic structure of 8 sub-optical switches is adopted to achieve a spectral resolution of 30pm within a spectral range of 1260nm to 1290nm, and the arm lengths of the non-equal-arm waveguides connected to the corresponding sub-optical switches are respectively shown in the following table:

reference numerals

Length of

Reference numerals

Length of

Reference numerals

Length of

Reference numerals

Length of

L11

L

L31

L

L51

L

L71

L

L12

L+ΔL

L32

L+4ΔL

L52

L+16ΔL

L72

L+64ΔL

L21

L+ΔL

L41

L+4ΔL

L61

L+16ΔL

L81

L+64ΔL

L22

L+3ΔL

L42

L+12ΔL

L62

L+48ΔL

L82

L+192ΔL

Wherein L is 152 μm, and Δ L is 5.51 μm. The number of spectral channels is 255, the maximum optical path difference is 1405.1 μm, and when the input optical spectral range is 1260, 1290nm, the corresponding spectral resolution is 30 pm.

According to another specific embodiment of the present application, as shown in fig. 2, the sub optical switch 204 includes a third coupler 300, a first phase shifter 301, a second phase shifter 302, and a fourth coupler 303, wherein an input end of the third coupler 300 is an input end of the sub optical switch 204; a first end of the first phase shifter 301 and a first end of the second phase shifter 302 are connected to an output end of the third coupler 300; an input end of the fourth coupler 303 is connected to a second end of the first phase shifter 301 and a second end of the second phase shifter 302, respectively, and an output end of the fourth coupler 303 is an output end of the sub optical switch 204.

In another specific embodiment of the present application, the second beam splitter includes a fifth coupler, and the second beam combiner 203 includes a sixth coupler. According to a more specific embodiment of the present application, the second beam splitter is the fifth coupler, and the second beam combiner is a sixth coupler.

In a specific embodiment, as shown in fig. 2, the second coupler is a 2 × 1 coupler, the fourth coupler is a 2 × 2 coupler, the fifth coupler is a 1 × 2 coupler, and the sixth coupler is a 2 × 1 coupler. The third coupler of the first sub optical switch is a 1 × 2 coupler, and the third coupler of the mth sub optical switch is a 2 × 2 coupler.

In practical application, the sub-optical switch is an electro-optical switch or a thermo-optical switch. In a specific embodiment, the sub-optical switch is a thermo-optical switch. Of course, those skilled in the art can also realize a sub-optical switch by using the carrier dispersion effect, which has the advantages of fast modulation speed and no relation with polarization, but has the defect of large loss.

According to a specific embodiment of the present application, the second coupler, the third coupler, the fourth coupler, the fifth coupler and the sixth coupler are independently selected from one or more of a silicon-based directional coupler, a silicon-based Y-type coupler and a multimode interference coupler. The skilled person can make a flexible choice depending on the actual situation. In order to ensure that the performance of the sub-splitting structure is good, the second coupler, the third coupler, the fourth coupler, the fifth coupler and the sixth coupler may be the same type of coupler, and in a more specific embodiment of the present application, the second coupler, the third coupler, the fourth coupler, the fifth coupler and the sixth coupler are all multimode interference couplers.

In a specific embodiment, the sub-optical switch is a thermo-optical switch, and as shown in fig. 3, the sub-optical switch further includes a heater 206, and the heater 206 covers the first phase shifter and the second phase shifter.

In a specific embodiment, the first coupler comprises a one-dimensional non-uniform period grating coupler. In a more specific embodiment, the first coupler is a one-dimensional non-uniform period grating coupler. The grating is a commonly used waveguide coupling structure for coupling external light to or from the optical splitter chip. The periodic one-dimensional grating is a polarization sensitive device, can only couple light in one polarization direction to the light splitting chip, and is low in energy utilization rate. Therefore, a one-dimensional non-uniform period grating coupler is used to achieve polarization insensitive coupling of the input light. The needed one-dimensional non-uniform period grating coupler is designed according to the performance index requirement by adopting a reverse design method and based on specific process conditions. A structure as shown in fig. 4 is obtained. Of course, one skilled in the art can also select a multidimensional unequal period grating coupler to be used as the first coupler.

As shown in fig. 4, according to the set 1260nm-1290nm spectral range, under the process conditions that the thickness of the silicon-based waveguide Si is 220nm, the grating etching depth is 70nm, and the minimum line width is 100nm, the optimal structure is searched for the performance index with the loss of less than 7dB @1275nm and the 3dB bandwidth of more than 30nm by using the global optimization algorithm with limited freedom. Meanwhile, the diameter of a light spot is set to be 9 mu m, the incident angle is set to be 8 degrees, and the total length of the grating area is set to be 30 mu m.

Searching an optimal structure through a genetic algorithm, wherein a fitness function is set as follows:

wherein, P_TProbability of peak value;

T_TEand T_TMTransmittance of light corresponding to TE and TM modes, respectively;

λ 1275nm as central wavelength;

λ 1 ═ 1260nm, and λ 2 ═ 1290nm correspond to the minimum and maximum wavelengths of the input light, respectively.

And inputting the individuals into the FDTD for simulation calculation through an optimization algorithm, returning the transmission spectrum of the FDTD simulation calculation to the algorithm, calculating the fitness and screening the optimal result. And obtaining the grating structure meeting the index requirement through iteration. Referring to fig. 5, a graph of simulation results for a one-dimensional non-uniform period grating coupler is shown. As can be seen from fig. 5, the wavelength of the one-dimensional non-uniform periodic grating coupler covers the wavelength range from 1260nm to 1290nm, the transmittance corresponding to the wavelength range from 1260nm to 1290nm is greater than 50% of the highest point of the transmittance, and the transmittance corresponding to the central wavelength of 1275nm in the wavelength range from 1260nm to 1290nm is the highest, which indicates that the one-dimensional non-uniform periodic grating coupler can meet the design requirement.

In another specific embodiment of the present application, the first coupler, the light splitting unit, and the detector are integrated by using a silicon CMOS process. According to the Fourier waveguide light splitting chip, the detector and the light splitting unit are arranged on the same chip, interference light is directly detected, loss caused by coupling in off-chip detection can be avoided, the high energy utilization rate is further guaranteed, and the high detection sensitivity is guaranteed.

The fourier waveguide optical splitting chip of the present application is subjected to simulation verification, and referring to fig. 6, the spectral distribution of an input signal to be measured is shown. Referring to fig. 7, output optical intensity signals of the fourier waveguide optical splitter chip of the present application corresponding to different optical path differences and wavelengths are shown. Referring to fig. 8, the light splitting effect of the fourier waveguide light splitting chip in the 1260-. As can be seen from fig. 6 and 8, the light splitting effect of the inner-lobe waveguide light splitting chip of the present application is better.

In the fourier waveguide spectroscopy chip of the present application, the chip is preferably made of a silicon material, but SiN, a polymer material, a iii-v material, etc. may also be selected, and a plurality of materials are doped to achieve low-loss transmission and specific spectral band filtering effects of the fourier waveguide spectroscopy chip.

It should be noted that the fourier waveguide optical splitter chip of the present application can be mass-produced based on a mature silicon optical process, so as to implement low-cost fabrication, and the system structure can be popularized and applied to other band ranges and other material systems.

From the above description, it can be seen that the above-described embodiments of the present application achieve the following technical effects:

the utility model provides a foretell Fourier type waveguide beam split chip, including the insensitive first coupler of polarization, beam split unit and the detector that connect gradually, above-mentioned first coupler is used for receiving the input light, and above-mentioned input light includes the light of a plurality of polarization directions, and above-mentioned beam split unit is used for carrying out the beam split to above-mentioned input light, and above-mentioned detector is used for the above-mentioned input light conversion after will splitting to the signal of telecommunication. The utility model provides an above-mentioned Fourier type waveguide spectral chip introduces chip level spectrum spectrometer through the above-mentioned first coupler insensitive with polarization, can a plurality of polarization direction's of simultaneous coupling input light, has guaranteed that the energy utilization of light source is higher, has solved chip level spectrum analyzer among the prior art better and has adopted polarization sensitive device, needs fixed polarization state input, leads to the lower problem of light energy utilization.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fourier waveguide optical splitter chip, comprising:

a first coupler that is a polarization insensitive coupler for receiving input light, the input light comprising light of a plurality of polarization directions;

the light splitting unit is connected with the first coupler and is used for splitting the input light;

and the detector is connected with the light splitting unit and is used for converting the input light after light splitting into a corresponding electric signal.

2. The fourier waveguide optical splitter chip of claim 1, wherein the optical splitter unit comprises:

a first beam splitter connected to the first coupler, the first beam splitter being configured to split the input light into first polarized light and second polarized light, a polarization direction of the first polarized light being perpendicular to a polarization direction of the second polarized light;

a first rotator connected to the first beam splitter, the first rotator configured to convert the first polarized light into the second polarized light or convert the second polarized light into the first polarized light;

the MZI spectrum splitting structure based on the optical switch is respectively connected to the first rotator and the first beam splitter, and is configured to split the received first polarized light to obtain a third polarized light, or split the received second polarized light to obtain a fourth polarized light, and includes two output interfaces, and is further configured to output the third polarized light through the two output interfaces, or output the fourth polarized light through the two output interfaces;

a second rotator connected to one of the two output interfaces, the second rotator configured to convert the third polarized light into the fourth polarized light or convert the fourth polarized light into the third polarized light;

and the first beam combiner is respectively connected with the other of the two output interfaces and the second rotator and is used for combining the received light.

3. A fourier waveguide optical splitter chip as defined in claim 2, wherein the first polarized light and the third polarized light are both shear waves, and the second polarized light and the fourth polarized light are both shear waves.

4. The fourier-waveguide optical splitter chip of claim 2, wherein the MZI optical spectrum optical splitter structure comprises two sub-optical splitter structures, wherein an input of one of the sub-optical splitter structures is connected to one of the first rotator and the first beam splitter, an input of the other of the sub-optical splitter structures is connected to the other of the first rotator and the first beam splitter, and an output of the sub-optical splitter structure is the output interface.

5. The Fourier waveguide spectroscopy chip of claim 4, wherein the sub-spectroscopic structure comprises:

the input end of the second beam splitter is the input end of the sub light splitting structure;

the cascade optical switches comprise N sub optical switches and N unequal-arm waveguides, wherein the input end of the first sub optical switch is connected with the output end of the second beam splitter, the Mth sub optical switch is connected with the M +1 th sub optical switch through the unequal-arm waveguides, and M is more than or equal to 1 and is less than N;

the input ends of the second couplers are connected with the output end of the Nth sub-optical switch through the Nth non-equal-arm waveguide;

and the input end of the second beam combiner is connected with the output ends of the plurality of second couplers, and the output end of the second beam combiner is the output end of the sub-light splitting structure.

6. The fourier waveguide optical splitter chip of claim 5, wherein the sub-optical switch comprises:

a third coupler, an input end of the third coupler being an input end of the sub optical switch;

a first end of the first phase shifter and a first end of the second phase shifter are respectively connected with an output end of the third coupler;

and an input end of the fourth coupler is connected with the second end of the first phase shifter and the second end of the second phase shifter respectively, and an output end of the fourth coupler is an output end of the sub-optical switch.

7. The Fourier waveguide splitter chip of claim 6, wherein the third coupler and the fourth coupler are each independently selected from one or more of a silicon-based directional coupler, a silicon-based Y-type coupler, and a multimode interference coupler.

8. The Fourier waveguide optical splitter chip of claim 5, wherein the second splitter comprises a fifth coupler and the second combiner comprises a sixth coupler.

9. The Fourier waveguide optical splitter chip of claim 5, wherein the sub-optical switches are electro-optical switches or thermo-optical switches.

10. A fourier waveguide optical splitter chip as claimed in any one of claims 1 to 9 wherein the first coupler comprises a one-dimensional non-uniform period grating coupler.

11. The fourier waveguide optical splitter chip of any one of claims 1 to 9, wherein the first coupler, the optical splitter unit, and the detector are integrated using a silicon CMOS process.