CN101286804A - Color dispersion detecting method and device - Google Patents

Abstract

The invention provides an optical dispersion detecting method and a device thereof, pertaining to the optical transmission filed. In order to solve the problems that the structure of the optical dispersion detecting device of the prior art is complex, the detecting speed is influenced by the complexity of the analysis of a sample, the confidence level of the optical dispersion analysis result depends on the strategy of the sample analysis and the precision of the sampling, the invention provides the optical dispersion detecting method. The method comprises the steps of the conversion of optical signals into amplitude modulation signals of optical dispersion, the obtaining of mean power of the amplitude modulation signals of the optical dispersion and the obtaining of optical dispersion value of optical signals according to a signal value relation between the mean power of the amplitude modulation signals of the optical dispersion and the optical dispersion of signals. The invention also provides an optical dispersion detecting device which comprises a capturing unit of the amplitude modulation signals of the optical dispersion, a power detecting unit and a lookup table corresponding unit. By adopting the proposal of the invention, the detecting device has simple structure, less hardware units, high detecting speed and comparatively high confidence level of the detecting result.

Description

A kind of chromatic dispersion detection method and device

Technical field

The present invention relates to the optical transmission field, particularly a kind of chromatic dispersion detection method and device.

Background technology

The various mode component of transmitted number different frequency component or signal cause that because of the transmission speed difference phenomenon of signal waveform distortion is called chromatic dispersion in the optical fiber in transmission course.The chromatic dispersion meeting makes and produces intersymbol interference between data pulse, thereby the damage that chromatic dispersion brings the optical transmission system performance can not ignore, and generally needs the dispersion compensation technology to guarantee the transmission performance of optical transmission system.Realize the optical transport network that dynamically to prepare for the two-forty optical transmission system more than the 40Gb/s or expectation, but the dispersion compensation solution that self adaptation is regulated is absolutely necessary.In order to realize the compensating adaptive dispersion system, chromatic dispersion detection and feedback control mechanism are necessary.

At present, the implementation method of high speed chromatic dispersion detection mainly contains following two kinds:

1. be conceived to the chromatic dispersion based on signal spectrum of chromatic dispersion causative research is detected implementation method.These class methods have sideband method, discrete component method and pilot tone system.Its detected object is an optical transmission medium, by the dispersion characteristics of light travels medium, and comes the dispersion values of approximate substitution light signal rather than the dispersion values of Direct-detection Optical signal itself with the dispersion values of particular spectral component.This class methods detection speed is fast, and is higher to the system hardware performance requirement, and testing result is limited to the reference value of the true dispersion characteristics of comprehensive assurance light signal.

Referring to Fig. 1, be a kind of chromatic dispersion detection scheme based on signal spectrum.This scheme is to demodulate baseband signal at receiving terminal by receiver, and extracts wherein clock signal as the reference clock; Simultaneously before the light signal that receives carries out opto-electronic conversion, by the upper sideband (VSB-U:Vestigial side band-Upper) of optical filter leaching signal spectrum or the signal of lower sideband (VSB-L:Vestigial side band-Low), after respectively upper sideband or lower sideband signal being carried out opto-electronic conversion by optical-electrical converter then, extract clock signal by the clock recovery device, and make the phase information sharpening of sideband signals; Judge the size of dispersion measure then by the phase difference of phase detectors comparison sideband signals and baseband signal two-way clock signal.This scheme needs two cover high speed optoelectronics conversions and handles structure in the process that produces baseband signal and sideband signals, makes the system configuration complexity.In addition, two cover clock recovery systems have greatly increased the realization cost of system.

2. the chromatic dispersion based on signal envelope that the signal impairment that is conceived to that chromatic dispersion is caused is studied detects implementation method.These class methods mainly are the sampling analysis methods.Its detected object is a light signal itself, draws analysis result to the signal dispersion situation by the statistical analysis to light signal time domain discrete sample.The statistical sample of these class methods is signals sampling values, and the confidence level of analysis result depends on the precision of Sampling techniques.The complexity of sample analysis is the main cause that influences such detection method speed.The confidence level of analysis result depends on the analysis strategy that the sample analysis technology adopts equally.

Referring to Fig. 2, be a kind of chromatic dispersion detection scheme based on signal envelope.At transmitting terminal, by on phase-modulator, loading the DPSK code signal, the light signal of distributed feedback laser output to be modulated, the output modulated light signal behind this signal process erbium-doped fiber amplifier and the attenuator, transmits in optical fiber.At receiving terminal, after tunable filter leaches light signal, this light signal is at first carried out asynchronous-sampling, then the mathematical feature of sample is analyzed, judge the size of dispersion measure by the single valued relation of sample and signal dispersion.

The algorithm chip of this scheme realizes generally all more complicated, detection speed limited (tens of second-time).

Summary of the invention

Chromatic dispersion checkout gear complex structure, detection speed are subjected to the influence of sample analysis complexity, the confidence level of chromatic dispersion analysis result to depend on the problem of the strategy and the sampling precision of sample analysis in the prior art in order to solve, provide a kind of fast, accurately, the simple chromatic dispersion detection method of implementation structure and device.Described technical scheme is as follows:

A kind of chromatic dispersion detection method said method comprising the steps of:

Light signal is converted to the chromatic dispersion amplitude-modulated signal;

Obtain the average power of described chromatic dispersion amplitude-modulated signal;

According to the average power of chromatic dispersion amplitude-modulated signal and the dispersion values of the acquisition of the single valued relation between signal dispersion light signal.

A kind of chromatic dispersion checkout gear, described device comprise chromatic dispersion amplitude-modulated signal acquiring unit, power detecting unit and the corresponding unit of tabling look-up;

Described chromatic dispersion amplitude-modulated signal acquiring unit is used for light signal is converted to the chromatic dispersion amplitude-modulated signal, and described chromatic dispersion amplitude-modulated signal is sent to described power detecting unit;

Described power detecting unit is used to receive described chromatic dispersion amplitude-modulated signal, obtains the average power of chromatic dispersion amplitude-modulated signal, and the average power of described diffusing amplitude-modulated signal is sent to the described corresponding unit of tabling look-up;

The described corresponding unit of tabling look-up is used to receive the average power of described chromatic dispersion amplitude-modulated signal, obtains the dispersion values of light signal according to the average power of chromatic dispersion amplitude-modulated signal.

The technical scheme that adopts the described scheme of the embodiment of the invention to provide is phase modulator and power detector owing to Primary Component, thereby simple in structure, and required hardware cell is less; Used this space of bulk sample of signal, testing result has higher confidence level; The software operation that relates to only is the searching of corresponding relation between detection limit and the dispersion values, thereby detection speed is fast.

Description of drawings

Fig. 1 is that the chromatic dispersion based on signal spectrum detects implementation structure figure in the prior art;

Fig. 2 is that the chromatic dispersion based on signal envelope detects implementation structure figure in the prior art;

Fig. 3 is the embodiment of the invention 1 a described chromatic dispersion detection method flow chart;

Fig. 4 is the embodiment of the invention 2 described chromatic dispersion detection method flow charts;

Fig. 5 is the structure chart of the described chromatic dispersion checkout gear of the embodiment of the invention;

Fig. 6 is the structure chart of the embodiment of the invention 3 described chromatic dispersion checkout gears;

Fig. 7 is the structure chart of the embodiment of the invention 4 described chromatic dispersion checkout gears;

Fig. 8 is the structure chart of the embodiment of the invention 5 described chromatic dispersion checkout gears;

Fig. 9 is the structure chart of the embodiment of the invention 6 described chromatic dispersion checkout gears;

Figure 10 is the structure chart of the embodiment of the invention 7 described chromatic dispersion checkout gears;

Figure 11 is the non-linear relation schematic diagram of the described phase width of cloth of embodiment of the invention converting unit power output and phase modulation unit input power;

Figure 12 is a corresponding relation schematic diagram between described input signal amplitude statistical variance of the embodiment of the invention and the output signal average power;

Figure 13 is the chromatic dispersion of input signal of the described phase modulation of embodiment of the invention unit and the single valued relation schematic diagram between the phase width of cloth converting unit output signal average power.

Embodiment

The invention will be further described below in conjunction with the drawings and specific embodiments, but the present invention is not limited to following examples.

The embodiment of the invention utilizes the variation of the signal transient amplitude statistics variance that chromatic dispersion brings at first the dispersion information of signal to be converted to the instantaneous phase information of signal, the instantaneous amplitude information of subsequently instantaneous phase information transform being write in reply number, the entrained dispersion information of statistical nature of the instantaneous amplitude information of this moment is converted to mathematic expectaion by statistical variance, therefore can come the dispersion information of picked up signal by the variation of detection signal average power.

The theoretical model that the embodiment of the invention relates to is as described below.

With zero Chirped Gaussian Pulses is example, signal through one section optical fiber after, its phase change is by φ _CDSign is modulated its phase place by a NLE (Nonlinear Element, non-linear unit) subsequently again, and the phase change here is by φ _CD+NLSign.Two phase changing capacities are shown below.The non-linear unit NLE here is made of one section HNLF (High Nonliner Fiber, highly nonlinear optical fiber).

${\mathrm{\&phi;}}_{\mathrm{CD}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,t)=-\frac{\mathrm{sgn}\left({\mathrm{\&beta;}}_2\right){\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\left|{\mathrm{\&beta;}}_2\right|}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\left|{\mathrm{\&beta;}}_2\right|}\&CenterDot;\frac{t^2}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2}+\frac{1}{2}\&CenterDot;\mathrm{<figure-callout\; id="1"\; label="arctan\; l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">arctan</figure-callout>}\frac{l_{}}{}\frac{{}_1\left|{\mathrm{\&beta;}}_2\right|}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2}---\left(1\right)$

${\mathrm{\&phi;}}_{\mathrm{CD}+\mathrm{NL}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">l</figure-callout>}}_2,t)={\mathrm{\&phi;}}_{\mathrm{CD}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,t)$

$+{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2\mathrm{\&gamma;}{P}_0{l}_2{({\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^4+{\mathrm{\&beta;}}_2^2{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1^2)}^{-1/2}\exp (-\frac{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2{t}^2}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^4+{\mathrm{\&beta;}}_2^2{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1^2})---\left(2\right)$

L wherein ₁And l ₂Be respectively the length of optical fiber and non-linear unit.T is that time-delay is the time.T ₀, γ and P ₀It is respectively the peak power of FWHM (Full Width at Half Maximum, full width at half maximum), non linear coefficient and the signal of signal.For the signal of 1550-nm window, abbe number β ₂Be negative, so formula (1) can be reduced to formula (3).

${\mathrm{\&phi;}}_{\mathrm{CD}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,t)=\frac{{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\left|{\mathrm{\&beta;}}_2\right|}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\left|{\mathrm{\&beta;}}_2\right|}\&CenterDot;\frac{t^2}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2}+\frac{1}{2}\&CenterDot;\mathrm{<figure-callout\; id="1"\; label="arctan\; l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">arctan</figure-callout>}\frac{l_{}}{}\frac{{}_1\left|{\mathrm{\&beta;}}_2\right|}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2}---\left(3\right)$

Under the simplest situation, after the synchronous addition of branch of two constant powers of signal, be φ (t) as the phase change of the combined signal of phase width of cloth converting unit output, its expression formula is

$\mathrm{\&phi;}\left(t\right)=\frac{{\mathrm{\&phi;}}_{\mathrm{CD}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,t)+{\mathrm{\&phi;}}_{\mathrm{CD}+\mathrm{NL}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">l</figure-callout>}}_2,t)}{2}---\left(4\right)$

Though no matter be that the energy of signal all remains unchanged through optical fiber dispersion or process non-linear unit: But after this phase width of cloth converting unit of process, its energy changes into

$E_{\mathrm{PM}-\mathrm{AM}}={\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2{({\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^4+{\mathrm{\&beta;}}_2^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">l</figure-callout>}}_2^2)}^{-1/2}$

$\&CenterDot;{\&Integral;}_{-{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0/2}^{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0/2}\exp (-\frac{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2{t}^2}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^4+{\mathrm{\&beta;}}_2^2{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1^2}){\cos }^2\left[\frac{{\mathrm{\&phi;}}_{\mathrm{CD}+\mathrm{NL}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">l</figure-callout>}}_2,t)-{\mathrm{\&phi;}}_{\mathrm{CD}}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1,t)}{2}\right]\mathrm{dt}$

$={\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2{({\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^4+{\mathrm{\&beta;}}_2^2{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1^2)}^{-1/2}$ (5)

$\&CenterDot;{\&Integral;}_{-{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0/2}^{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0/2}\exp (-\frac{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2{t}^2}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^4+{\mathrm{\&beta;}}_2^2{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1^2}){\cos }^2\left[\frac{\mathrm{\&Delta;\&phi;}\left(t\right)}{2}\right]\mathrm{dt}$

Here, definition phase change Δ φ (t)=φ _CD+NL(l ₁, l ₂, t)-φ _CD(l ₁, t).If each parameter of non-linear unit and signal itself is fixed β ₂L ₁Expression chromatic dispersion, this ENERGY E so _PM-AMJust become the function of signal dispersion, as the formula (6)

E _PM-AM＝f(β ₂·l ₁) (6)

In order to improve detection sensitivity, can between two paths of signals, introduce extra phase difference

Phase change Δ φ (t) is positioned near k π ± pi/2, and wherein k is an integer.Formula (5) just becomes formula (7) so

$E_{\mathrm{PM}-\mathrm{AM}}={\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2{({\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071006525000191.png"\; state="\{\{state\}\}">T</figure-callout>}}_0^2+{\mathrm{\&beta;}}_2^2{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20071006525000171.png,A20071006525000173.png"\; state="\{\{state\}\}">l</figure-callout>}}_1^2)}^{-1/2}$

Embodiment 1

Referring to Fig. 3, the method that the embodiment of the invention provides a kind of chromatic dispersion to detect, concrete steps are as follows:

Step 201: input optical signal is carried out phase modulated, produce phase modulated signal.

Phase modulated to input optical signal can adopt SOA (Semiconductor Optical Amplifier, semiconductor optical amplifier) or HNLF (High Nonliner Fiber, highly nonlinear optical fiber), also can adopt other nonlinear device based on Kerr effect (Kerr effect), the signal envelope that chromatic dispersion is caused by phase modulated rises and falls and is converted into the instantaneous phase information of signal.

Step 202: phase modulated signal is carried out the conversion of the phase width of cloth, produce the chromatic dispersion amplitude-modulated signal.

In this step, the phase modulated signal that carries instantaneous phase information is separated into the multichannel phase modulated signal by branching unit, phase shift is carried out by the time delay unit in each road in the multichannel phase modulated signal, after phase modulated signal after the phase shift interfered addition by combiner unit, be merged into the chromatic dispersion amplitude-modulated signal, make the average power of chromatic dispersion amplitude-modulated signal change, this changes with instantaneous phase information strong correlation.In this step, the instantaneous phase information of signal is converted into the instantaneous amplitude information of signal, and its dispersion information is by the statistical property carrying of signal transient amplitude.

When having one tunnel time delay to be zero in the time delay unit, the phase modulated signal of this road correspondence just directly sends to combiner unit.

Step 203: the average power that detects the chromatic dispersion amplitude-modulated signal.

The detection of average power can be finished by a PIN (photodiode) detector, to obtain the statistical property of the chromatic dispersion amplitude-modulated signal instantaneous amplitude that carries dispersion information.

Step 204: the dispersion values that utilizes the average power of chromatic dispersion amplitude-modulated signal and the single valued relation picked up signal between the signal dispersion.

Owing to have single-valued relationship between the average power of chromatic dispersion amplitude-modulated signal and the signal dispersion, can pass through dispersion values such as look-up table or other method such as curve-fitting method etc. according to the average power picked up signal of chromatic dispersion amplitude-modulated signal.

Embodiment 2

Among the embodiment 1, conversion is separately to realize to phase modulated with the width of cloth mutually, but this separation relation is not necessary.Referring to Fig. 4, in the present embodiment, conversion is integrated phase modulated with the width of cloth mutually, and the specific implementation method is as follows:

Step 301: input optical signal is separated into multiple signals through branching unit.

Step 302: phase shift and phase modulation are carried out by time delay unit and phase modulation unit respectively in each road in the multiple signals of separating in the step 301.In this step, also can carry out phase modulation earlier, carry out phase shift again.

Step 303: merge being input to combiner unit through each the road signal behind phase shift and the phase modulation in the step 302, produce the chromatic dispersion amplitude-modulated signal.

Step 304,305 with step 203,204 identical, repeat no more.

The embodiment of the invention also provides a kind of chromatic dispersion checkout gear, the variation that utilizes the signal envelope that chromatic dispersion causes by non-linear unit adjusts accordingly the phase information of signal, utilize subsequently based on the phase width of cloth converting unit of interference device the phase modulated signal of multiple branch circuit is done linearity or nonlinear combination so that obtain the chromatic dispersion amplitude-modulated signal of changes in amplitude reaction phase change, utilize the average power of power detecting unit detection chromatic dispersion amplitude-modulated signal at last, extract the dispersion information of signal by the variation of this average power.

Referring to Fig. 5, chromatic dispersion detects (CDM, Chromatic Dispersion Monitoring) device and is made of phase modulation unit 401, phase width of cloth converting unit 402, power detecting unit 403 and the corresponding unit 404 of tabling look-up.

Phase modulation unit 401 is used for input optical signal is carried out phase modulated, and the signal transient changes in amplitude that dispersion variation is caused converts the variation of signal transient phase place to, thereby produces phase modulated signal, and phase modulated signal is sent to phase width of cloth converting unit 402.Wherein the variation of this signal transient amplitude can not cause the variation of average power signal.

Phase width of cloth converting unit 402 is used to receive the phase modulated signal that phase modulation unit 401 sends, described phase modulated signal is carried out the conversion of the phase width of cloth, the phase change of signal is converted to the signal transient changes in amplitude, thereby produce the chromatic dispersion amplitude-modulated signal, and the chromatic dispersion amplitude-modulated signal is sent to power detecting unit 403.Wherein the variation of signal transient amplitude will cause the variation of average power signal, make the variation of chromatic dispersion amplitude-modulated signal average power carry the signal dispersion change information.

Power detecting unit 403 is used to receive the chromatic dispersion amplitude-modulated signal that phase width of cloth converting unit 402 sends, and obtains the average power of chromatic dispersion amplitude-modulated signal, and the average power of described chromatic dispersion amplitude-modulated signal is sent to the corresponding unit 404 of tabling look-up.Wherein, power detecting unit can be multistage photodetector unit, can detection power, and n root or n power that also can detection power promptly can the relevant unified amounts of detection power.

The corresponding unit 404 of tabling look-up is used to obtain the average power of the chromatic dispersion amplitude-modulated signal that described power detecting unit 403 sends, the dispersion values that obtains described light signal according to the average power and the single valued relation between the signal dispersion of chromatic dispersion amplitude-modulated signal.

Phase modulation unit 401 lumps together with width of cloth converting unit 402 mutually forms chromatic dispersion amplitude-modulated signal acquiring unit.

Adopt 3,4 pairs of above-mentioned chromatic dispersion checkout gears of specific embodiment to specify below.

Embodiment 3

Referring to Fig. 6, SOA401a is the phase modulation unit; The merit proportion by subtraction is to prolong unit 402b 1: 1 power splitter 402a, light time to have constituted width of cloth converting unit mutually with wave multiplexer 402c; PIN detector 403a is a power detecting unit.In order to improve detection sensitivity, can also in PIN detector 403a, add the high-order device.In the present embodiment, the phase modulation unit can also be HNLF except being the SOA401a, or other the nonlinear device based on light Kerr effect.

SOA401a is used for input optical signal is carried out phase modulated, the signal transient changes in amplitude that dispersion variation is caused converts the variation of signal transient phase place to, thereby the generation phase modulated signal, and phase modulated signal sent to power splitter 402a in the phase width of cloth converting unit.Wherein the variation of this signal transient amplitude can not cause the variation of average power signal.

Power splitter 402a is used to receive the phase-modulated signal that phase modulation unit 401 sends, and phase modulated signal is separated into the two-way phase modulated signal, wherein one road phase modulated signal sends to the light time and prolongs unit 402b, and another road phase modulated signal sends to wave multiplexer 402c.

Light time prolongs unit 402b and is used to receive the road phase modulated signal that power splitter 402a sends, and this road phase modulated signal is carried out phase shift, and the signal after the phase shift is sent to wave multiplexer 402c;

Wave multiplexer 402c is used for producing the chromatic dispersion amplitude-modulated signal, and sending to PIN detector 403a merging through road phase modulated signal after the phase shift and another road phase modulated signal.

PIN detector 403a is used for receiving the chromatic dispersion amplitude-modulated signal that phase width of cloth converting unit wave multiplexer 402c sends, and obtains the average power of chromatic dispersion amplitude-modulated signal, and the average power of this chromatic dispersion amplitude-modulated signal is sent to the corresponding unit 404 of tabling look-up.

The corresponding unit 404 of tabling look-up is used to obtain the average power of the chromatic dispersion amplitude-modulated signal that PIN detector 403a sends, the dispersion values that obtains light signal according to the average power and the single valued relation between the signal dispersion of chromatic dispersion amplitude-modulated signal.

Embodiment 4

Among the embodiment 3, adopted a light time to prolong the unit, in order to obtain better effect, referring to Fig. 7, in the present embodiment, phase width of cloth converting unit comprises branching unit 402d, time delay unit 402e and combiner unit 402f.Wherein, time delay unit 402e is made of N discrete time delay unit, and this N discrete time delay unit is parallel-connection structure.Branching unit 402d is for waiting subdivision, and this unit receives the phase modulated signal that phase modulation unit 401 sends, and exports N the phase modulated signal that power is identical, and is input to N time delay unit respectively, and promptly the power of signal is identical on each time delay branch road.Phase modulated signal after the output phase shift of N time delay unit also is input to combiner unit 402f, and combiner unit 402f output chromatic dispersion amplitude-modulated signal is converted to the signal transient changes in amplitude with the phase change of signal.In order to improve detection sensitivity, phase width of cloth converting unit can be made of the higher order filter of a band amplifier/attenuator.Other unit and the annexation of present embodiment are identical with embodiment 3, repeat no more.

Embodiment 5

In embodiment 3 and embodiment 4, the phase modulation unit separates from structure with phase width of cloth converting unit, this structural separation relation is not essential, can combine to form chromatic dispersion amplitude-modulated signal acquiring unit, realizes the phase modulation unit and the function of width of cloth converting unit mutually jointly.

Referring to Fig. 8, the chromatic dispersion checkout gear in the present embodiment comprises branching unit 402d, time delay unit 402e, phase modulation unit 401g, combiner unit 402f, power detecting unit 403 and the corresponding unit 404 of tabling look-up.

Branching unit 402d waits subdivision, is used for input optical signal is separated N the signal that power is identical, and each road signal is sent to time delay unit 402e.

Time delay unit 402e is made of N discrete time delay unit, this N discrete time delay unit is parallel-connection structure, be used to receive each road signal that branching unit 402d sends, phase shift carried out on each road in the multiple signals respectively, and the signal after the phase shift is sent to phase modulation unit 401g.

Phase modulation unit 401g is made of N discrete phase modulation unit, this N discrete phase modulation unit is parallel-connection structure, be used for the signal after the phase shift that receive time delay unit 402e sends, each the road signal after the phase shift carried out phase modulation, and the signal behind the phase modulation is sent to combiner unit 402f.

Combiner unit 402f is used to receive the signal that phase modulation unit 401g sends, and will merge through each the road signal behind phase shift and the phase modulation, produces the chromatic dispersion amplitude-modulated signal, and sends to power detecting unit 403.

Time delay unit 402e and phase modulation unit 401g have constituted time delay and phase modulation unit.

Other unit and the annexation of present embodiment are identical with embodiment 3, repeat no more.

Embodiment 6

Referring to Fig. 9, in embodiment 5, the position of time delay unit 402e and phase modulation unit 401g also can exchange, and promptly can carry out phase shift behind the advanced row phase modulation, after branching unit 402d is separated into multiple signals with input optical signal, each the road signal in the multiple signals is sent to phase modulation unit 401g earlier.

Phase modulation unit 401g is made of N discrete phase modulation unit, this N discrete phase modulation unit is parallel-connection structure, be used to receive the signal after the separation that branching unit 402d sends, each the road signal after separating carried out phase modulation, and the signal behind the phase modulation is sent to time delay unit 402e.

Time delay unit 402e is made of N discrete time delay unit, this N discrete time delay unit is parallel-connection structure, after being used to receive each road signal of phase modulation unit 401g transmission, phase shift being carried out on each road in the multiple signals respectively, and the signal after the phase shift is sent to combiner unit 402f.

Time delay unit 402e and phase modulation unit 401g have constituted time delay and phase modulation unit.

Other unit and the annexation of present embodiment are identical with embodiment 5, repeat no more.

Embodiment 7

Embodiment 3 to embodiment 6 is based on feed forward architecture, can adopt loop structure in the present embodiment.Referring to Figure 10, in the present embodiment, the chromatic dispersion checkout gear comprises branch/combiner unit 501, phase modulation unit 401, fiber optic loop 502, power detecting unit 403 and the corresponding unit 404 of tabling look-up.Wherein branch/combiner unit 501 can be one 2 * 2 a optical coupler, phase modulation unit 401 can be SOA, HNLF or other nonlinear device, fiber optic loop 502 uses ordinary optic fibre to get final product, branch/combiner unit 501, phase modulation unit 401 and typical NOLM (Nonlinear Optical Loop Mirror of fiber optic loop 502 common formations, non-linear ring of light mirror) ring mirror, wherein the starting point of fiber optic loop links to each other with branch/combiner unit 501, phase modulation unit 401 is positioned at the position of stray fiber loop center Δ τ, wherein Δ τ is the transmission time of loop center position to phase modulation unit 401, make two tributary signals that behind undue/combiner unit 501, produce in different time point process phase modulation unit 401, thereby played the effect of time delay unit.

Input optical signal is divided into along the clockwise branch road I of ring mirror behind branch/combiner unit 501 _cWith the anticlockwise branch road I of edge ring mirror _CcArticle two, tributary signal arrives the phase modulation unit at different time points, thereby makes along the anticlockwise branch road I of ring mirror _CcSignal with respect to along ring mirror clockwise branch road I _cSignal produce time delay, these two signals produce phase modulated signal respectively after through phase modulation unit 401, and are input to branchs/combiner unit 501, this branch/combiner unit 501 merges phase modulated signal, exports the chromatic dispersion amplitude-modulated signal to power detecting unit 403.Power detecting unit 403 is used to receive the chromatic dispersion amplitude-modulated signal that branch/combiner unit 501 sends, and obtains the average power of chromatic dispersion amplitude-modulated signal, and the average power of described chromatic dispersion amplitude-modulated signal is sent to the corresponding unit 404 of tabling look-up.The corresponding unit 404 of tabling look-up is used to obtain the average power of the chromatic dispersion amplitude-modulated signal that described power detecting unit 403 sends, the dispersion values that obtains described light signal according to the average power and the single valued relation between the signal dispersion of chromatic dispersion amplitude-modulated signal.

Below by empirical curve to the explanation of code stream situation to the present invention's checking that experimentizes.Figure 11, Figure 12, Figure 13 are 40Gbps signal dispersion test experience curve, and the sign indicating number type is NRZ.

Referring to Figure 11, be the non-linear relation between the power output of the input power of phase modulation unit 401 and width of cloth converting unit 402 mutually.Because the instantaneous strength of input signal is an amount that is difficult to represent, but can be similar to its statistical variance, therefore, as can be seen, the instantaneous strength statistical variance that the output signal average power of phase width of cloth converting unit 402 is exchanged the input signal of facies unit 401 is the input power sensitivity from curved line relation shown in Figure 11.

Referring to Figure 12, when being 60mW for the input signal average power, the corresponding relation between input signal amplitude statistical variance and the output signal average power.That is: phase modulation unit 401 makes input light instantaneous amplitude keep producing the variance function of chromatic dispersion under the constant condition of mathematic expectaion.Though promptly instantaneous strength is an amount that is difficult to represent, we can be similar to its statistical variance.

Referring to Figure 13, be the single valued relation between the output signal average power of the chromatic dispersion of the input signal of phase modulation unit 401 and phase width of cloth converting unit 402.Utilize this single-valued relationship just can come the dispersion values of picked up signal by the output signal average power that detects phase width of cloth converting unit 402.

The chromatic dispersion detection scheme that the embodiment of the invention provides is a detected object with the degree of impairment of signal envelope directly, and the chromatic dispersion that belongs to based on signal envelope detects implementation method.Owing to this space of bulk sample of having used signal, guaranteed the confidence level of testing result from detected object.The software operation that this detection method relates to only is the searching of corresponding relation between detection limit and the dispersion values, so its detection speed is suitable with the detection speed of sideband method, has the less advantage of fast, simple in structure, the required hardware cell of detection speed.

Simultaneously, change, thereby the embodiment of the invention can detect PMD because PMD causes the envelope variance equally, promptly transparent to PMD; By checking that RZ/NRZ/CSRZ is experimentized, the embodiment of the invention has adaptability to intensity modulated class sign indicating number type; Because phase place comparing class method has cycle samsara problem, this has limited the chromatic dispersion detection range, and the described technical scheme of the embodiment of the invention is the detection to variance in essence, because being monodrome, variance changes, so there is not the detection range upper limit in the embodiment of the invention in theory, therefore and phase place comparing class detection method comparatively speaking, the embodiment of the invention has bigger detection range; Because the embodiment of the invention is detection to the full signal sample, rather than to the detection of local sample of signal, the experimental result by the embodiment of the invention relatively and the experimental result of other scheme draw the embodiment of the invention and also have quite good detecting sensitivity.

Above-described embodiment is a more preferably embodiment of the present invention, and common variation that those skilled in the art carries out in the technical solution of the present invention scope and replacement all should be included in protection scope of the present invention.

Claims (14)

1. a chromatic dispersion detection method is characterized in that, said method comprising the steps of:

Light signal is converted to the chromatic dispersion amplitude-modulated signal;

Obtain the average power of described chromatic dispersion amplitude-modulated signal;

According to the average power of described chromatic dispersion amplitude-modulated signal and the dispersion values of the acquisition of the single valued relation between signal dispersion light signal.

2. chromatic dispersion detection method as claimed in claim 1 is characterized in that, the described step that light signal is converted to the chromatic dispersion amplitude-modulated signal specifically comprises:

Light signal is carried out phase modulated, produce phase modulated signal;

Described phase modulated signal is carried out the conversion of the phase width of cloth, produce the chromatic dispersion amplitude-modulated signal.

3. chromatic dispersion detection method as claimed in claim 2 is characterized in that, described described phase modulated signal is carried out phase width of cloth conversion, and the step that produces the chromatic dispersion amplitude-modulated signal specifically comprises:

Described phase modulated signal is separated into the two-way phase modulated signal;

In the described two-way phase modulated signal a road carried out phase shift, obtain phase modulated signal through phase shift;

Through one road phase modulated signal of phase shift with not through another road phase modulated signal merging of phase shift, produce the chromatic dispersion amplitude-modulated signal with described.

4. chromatic dispersion detection method as claimed in claim 2 is characterized in that, described described phase modulated signal is carried out phase width of cloth conversion, and the step that produces the chromatic dispersion amplitude-modulated signal specifically comprises:

Described phase modulated signal is separated into the multichannel phase modulated signal;

Phase shift is carried out on each road in the described multichannel phase modulated signal respectively, obtained phase modulated signal through phase shift;

Merge through each the road phase modulated signal after the phase shift described, produce the chromatic dispersion amplitude-modulated signal.

5. chromatic dispersion detection method as claimed in claim 1 is characterized in that, the described step that light signal is converted to the chromatic dispersion amplitude-modulated signal specifically comprises:

With separate optical signals is multiple signals;

Each road in the described multiple signals is carried out phase shift and phase modulation respectively;

Merge through each the road signal behind phase shift and the phase modulation described, produce the chromatic dispersion amplitude-modulated signal.

6. chromatic dispersion detection method as claimed in claim 1 is characterized in that, the described step that light signal is converted to the chromatic dispersion amplitude-modulated signal specifically comprises:

Light signal is separated into two paths of signals in the starting point of fiber optic loop;

Described two ways of separated signal is transferred to the position of departing from described optical fiber loop center carrying out phase shift along the clockwise branch road of fiber loop mirror and anticlockwise branch road respectively, and carry out phase modulation respectively;

Merge through the two paths of signals behind phase shift and the phase modulation described, produce the chromatic dispersion amplitude-modulated signal.

7. a chromatic dispersion checkout gear is characterized in that, described device comprises chromatic dispersion amplitude-modulated signal acquiring unit, power detecting unit and the corresponding unit of tabling look-up;

Described chromatic dispersion amplitude-modulated signal acquiring unit is used for light signal is converted to the chromatic dispersion amplitude-modulated signal, and described chromatic dispersion amplitude-modulated signal is sent to described power detecting unit;

Described power detecting unit is used to receive described chromatic dispersion amplitude-modulated signal, obtains the average power of chromatic dispersion amplitude-modulated signal, and the average power of described diffusing amplitude-modulated signal is sent to the described corresponding unit of tabling look-up;

The described corresponding unit of tabling look-up is used to receive the average power of described chromatic dispersion amplitude-modulated signal, obtains the dispersion values of light signal according to the average power of chromatic dispersion amplitude-modulated signal.

8. chromatic dispersion checkout gear as claimed in claim 7 is characterized in that, described chromatic dispersion amplitude-modulated signal acquiring unit comprises phase modulation unit and width of cloth converting unit mutually;

Described phase modulation unit is used for light signal is carried out phase modulated, produces phase modulated signal, and described phase modulated signal is sent to described phase width of cloth converting unit;

Described phase width of cloth converting unit is used to receive described phase modulated signal, and described phase modulated signal is carried out the conversion of the phase width of cloth, produces the chromatic dispersion amplitude-modulated signal.

9. chromatic dispersion checkout gear as claimed in claim 8 is characterized in that, described phase width of cloth converting unit comprises branching unit, time delay unit and combiner unit;

Described branching unit is used for described phase modulated signal is separated into two-way, and road phase modulated signal after the described separation is sent to described time delay unit, and another road phase modulated signal directly sends to described combiner unit;

Described time delay unit is used to receive described one road phase modulated signal and carries out phase shift, and sends to described combiner unit with described through road phase modulated signal after the phase shift;

Described combiner unit is used to receive the phase modulated signal that phase shift is not passed through on another road that phase modulated signal and described branching unit through phase shift that described time delay unit sends send, merge through one road phase modulated signal of phase shift and another road phase modulated signal of described not process phase shift described, produce the chromatic dispersion amplitude-modulated signal.

10. chromatic dispersion checkout gear as claimed in claim 8 is characterized in that, described phase width of cloth converting unit comprises branching unit, time delay unit and combiner unit;

Described branching unit is used for described phase modulated signal is separated into the multichannel phase modulated signal, and each the road phase modulated signal after the described separation is sent to described time delay unit;

Described time delay unit is used to receive described phase modulated signal, and phase shift is carried out on each road in the described multichannel phase modulated signal respectively, and sends to described combiner unit with described through each the road phase modulated signal after the phase shift;

Described combiner unit is used to receive described phase modulated signal through phase shift, merges through each the road phase modulated signal after the phase shift described, produces the chromatic dispersion amplitude-modulated signal.

11. chromatic dispersion checkout gear as claimed in claim 7 is characterized in that, described chromatic dispersion amplitude-modulated signal acquiring unit comprises branching unit, time delay and phase modulation unit, combiner unit;

It is multiple signals that described branching unit is used for separate optical signals, and each the road signal in the described multiple signals is sent to described time delay and phase modulation unit;

Described time delay and phase modulation unit are used to receive described each road signal, and each road in the described multiple signals is carried out phase shift and phase modulation respectively, and send to described combiner unit with described through the signal behind phase shift and the phase modulation;

Described combiner unit receives described through the signal behind phase shift and the phase modulation, merges through each the road signal behind phase shift and the phase modulation described, produces the chromatic dispersion amplitude-modulated signal.

12. chromatic dispersion checkout gear as claimed in claim 7 is characterized in that, described chromatic dispersion amplitude-modulated signal acquiring unit comprises branch/combiner unit, fiber optic loop and phase modulation unit;

The starting point of described fiber optic loop links to each other with described branch/combiner unit, and described phase modulation unit is positioned at the position of departing from described optical fiber loop center;

Described branch/combiner unit is used for light signal is separated into two paths of signals in the starting point of fiber optic loop; The two paths of signals of described separation by described fiber optic loop respectively along position that the clockwise branch road of fiber loop mirror and anticlockwise branch road transfer to place, described phase modulation unit carrying out phase shift, and the two paths of signals after the described phase shift transferred to described phase modulation unit carry out phase modulation respectively;

Described branch/combiner unit also is used for merging through the two paths of signals behind phase shift and the phase modulation described, produces the chromatic dispersion amplitude-modulated signal.

13., it is characterized in that described phase modulation unit is semiconductor optical amplifier, highly nonlinear optical fiber or based on the nonlinear device of optical Kerr effect as the described chromatic dispersion checkout gear of any claim among the claim 8-12.

14., it is characterized in that described power detecting unit is linearity or nonlinear optical power conversion device as the described chromatic dispersion checkout gear of any claim among the claim 7-12.

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