CN103576222B - CS-RZ to NRZ pattern upconversion fiber grating design method and device thereof - Google Patents

Abstract

The invention discloses a kind of method for designing and device thereof of CS-RZ to NRZ pattern upconversion fiber grating, the method comprises given one group of pseudo-random code, according to the discretize sequence of values of given dutycycle, signal rate acquisition CS-RZ code and NRZ code; Fast fourier transform is done to two groups of discretize sequence of values, obtains the discretize sequence of values of the two power spectrum; By wavelength width corresponding for the bit rate of the centre wavelength blue shift of the discretize sequence of values of the power spectrum of CS-RZ signal or red shift half CS-RZ signal, obtain CS-RZ signal spectrum; Deduct CS-RZ signal spectrum by the discretize sequence of values of NRZ power spectrum and obtain one group of new discretize sequence of values; Choosing cutting width is that the crop window of the wavelength width that the bit rate of two CS-RZ signals is corresponding carries out cutting to new discretize sequence of values, obtains the characteristic spectrum that fiber grating is complete; Reverse layer strip is utilized to obtain the structure of grating.Good wave filtering effect of the present invention, effectively can suppress pattern effect and ripple pulsation, obtain higher Q value.

Description

CS-RZ to NRZ pattern upconversion fiber grating design method and device thereof

Technical field

The present invention relates to technical field of optical network communication, in particular a kind of from Carrier-Suppressed Return-to-Zero (CS-RZ) to the full optical code type conversion apparatus of nonreturn to zero code (NRZ).

Background technology

Following high-speed high capacity optical communication system will merge dense wave division multipurpose (DWDM) and Optical Time Division Multiplexing (OTDM) technology on the one hand to improve transmission capacity and speed.On the other hand, in order to improve further optical communication system transmission capacity, improve band efficiency (spectralefficiency, be called for short SE), many novel, there is EO-1 hyperion efficiency, the modulation format of unique transport property will be used.New modulation techniques becomes one of gordian technique in High Speed System.Along with people's going deep into modulation technical research, except zero (RZ) code and these traditional modulation formats of non-return-to-zero (NRZ) code, various new modulation format continues to bring out, and Carrier-Suppressed Return-to-Zero (CS-RZ) is exactly one of them.This modulation format is proposed in 1999 first by MIYAMOTO, belongs to pseudo-Multi-level modulation fomats.This modulation format itself is both with amplitude modulation information, also with phase information, it is OOK (alternating-phaseOOK) modulation format of a kind of phase place change, come from the angle of dispersion tolerance, SPM tolerance limit, nonlinear impairments tolerance limit, CS-RZ code is a kind of well modulation format.

The spectrum of CS-RZ is narrow, is about the half of RZ code, thus spectrum efficiency comparatively RZ code is high; In addition, it is warbled and is mainly present in the place that two pulses connect, therefore higher to the tolerance of dispersion.There are some researches show, CS-RZ code is obviously better than NRZ code in the impact alleviating nonlinear effect, and it not only allows higher launched power, and Power penalty is also significantly less than NRZ code, is suitable for backbone network.

Nonreturn to zero code (NRZ) has that production method is simple, frequency band is narrow, have channel wavelength spacing closely, the advantages such as higher spectrum efficiency, is suitable for being applied in requiring in higher dense wave division multipurpose (DWDM) technology to spectrum efficiency; In addition, NRZ pattern also has the friendly to electronics device, stronger time jitter tolerance and dispersion tolerance but non-linear tolerance is low, transmission range near, is therefore generally suitable for Metropolitan Area Network (MAN) and Access Network.

Different OOK patterns, because having different time domains, frequency domain characteristic and be suitable for different networks, so at the high speed OTDM of commercialization and the interface of DWDM network system, between various OOK pattern the pattern switch technology, particularly all-optical data format conversion technology of mutually conversion become important, one of requisite network interface techniques.

At present, the pattern about NRZ to CS-RZ is changed, and WandiLi, JianWang etc. have reported two kinds of technical schemes:

1. utilize semiconductor optical amplifier to form the active pattern switch technology (W.D.Li of fiber loop mirror, M.H.Chen, Y.Dong, andS.Z.Xie, " All-opticalformatconversionfromNRZtoCSRZandbetweenRZandC SRZusingSOA-basedfiberloopmirror; " IEEEPhoton.Technol.Lett.16,203-205 (2004) .);

2. utilize the nontransparent characteristic of periodically poled LiNbO3 (PPLN) optical waveguide to realize the active pattern switch technology (JianWang of NRZ-to-CSRZ, JunqiangSun, XinliangZhang, andDexiuHuang, / ProposalforPPLN-Basedall-opticalNRZ-to-CSRZ, RZ-to-CSRZ, RZ-DPSK-to-CSRZ-DPSK, andRZ-DPSK-to-CSRZ-DPSKformatconversions, 0IEEEPhotonicsTechnol.Lett.20,1039-1041 (2008), and about the all-optical data format conversion of CS-RZ to NRZ, the people such as current only YuYu report one and utilize Mach-Zehnder to interfere (optical-fiber time-delay interferometer, DI) the passive pattern switch technology scheme (YuYu of cascade narrow band filter, XinliangZhang, andDexiuHuang, ' All-OpticalFormatConversionfromCs-RztoNrzat40gbit/S', Opticsexpress, 15 (2007), 5693-98, YuYu, XinliangZhang, andDexiuHuang, ' SimultaneousAll-OpticalMulti-ChannelRzandCsrztoNrzFormat Conversion', OpticsCommunications, 284 (2011), 129-35).The program can work in passive mode, although confronting active pattern switching device, have structure simple, cost performance is high, steady performance.Its shortcoming is: 1. owing to have employed the structure of the interferometers such as DI, adjustment operation is more difficult, and cost is higher; 2. adopt the scheme of interferometer cascading filter, be actually, with two wave filters, the function that secondary cutting realizes pattern conversion carried out to frequency spectrum, the technology of only carrying out a cutting straight forming with a wave filter is not provided, cause prior art relative complex, cost improves relatively, is unfavorable for that batch uses in commercial system; 3. filter effect is not good enough, and pattern effect is obvious.The symmetric form spectral response that two filter banks obtain has not been the optimal spectrum response of CS-RZ to NRZ pattern conversion, and optimal spectrum response should be carried out specific design according to the frequency spectrum difference of both CS-RZ, NRZ and obtain.

Summary of the invention

Object of the present invention, overcome the deficiencies in the prior art exactly, a kind of passive CS-RZ to NRZ all-optical data format conversion special purpose device based on blade type spectral response fiber grating and method for designing thereof are provided, this is different from the existing device carrying out secondary spectrum cutting based on interferometer cascade narrow band filter, the fiber grating filter that only need be designed by method for designing of the present invention, without the need to additional other active or passive device any.

In order to achieve the above object, following technical scheme is adopted:

A kind of CS-RZ to NRZ pattern upconversion fiber grating design method, bag following steps:

A given group code stream length is 2 ⁿthe pseudo-random code of-1, provides the discretize sequence of values of CS-RZ code and NRZ code when dutycycle is certain value, signal rate is definite value;

Fast fourier transform is done to two groups of discretize sequence of values, in units of decibel, obtains the discretize sequence of values of the two power spectrum;

By wavelength width corresponding for the bit rate of the centre wavelength blue shift of the discretize sequence of values of the power spectrum of CS-RZ signal or red shift half CS-RZ signal, obtain the CS-RZ signal spectrum after centre wavelength blue shift or red shift;

One group of new discretize sequence of values is obtained with the CS-RZ signal spectrum after the discretize sequence of values of NRZ power spectrum deducts blue shift or red shift;

Choosing cutting width is that the crop window of the wavelength width that the bit rate of two CS-RZ signals is corresponding carries out cutting to new discretize sequence of values, obtains the characteristic spectrum that fiber grating is complete;

According to the characteristic spectrum of fiber grating, adopt and comprise the structure that discrete reverse layer strip obtains grating.

Fiber grating device is transformed according to CS-RZ to the NRZ pattern that the design of above-mentioned method for designing obtains, for the CS-RZ signal to be converted of setting signal speed being converted to the NRZ signal of same signal rate, comprise the fiber grating with blade type spectral response, it is made up of fiber grating main body and grating first port and grating second port two ports.

Further, also comprise a circulator, described circulator is connected with fiber grating, and CS-RZ signal to be converted enters from circulator, then is back to circulator after entering into fiber grating, and exports from circulator.

Further, described signal rate is more than or equal to 10Gbit/s, and is less than or equal to 200Gbit/s.

Compared with prior art, beneficial effect of the present invention is:

1. the conversion device structure obtained by method for designing of the present invention design is simple, and using easy to operate: whole conversion equipment is reduced to the fiber grating that has blade type spectral response, is a kind of CS-RZ to the NRZ full optical code type conversion apparatus simplified most.

2. good wave filtering effect, effectively can suppress pattern effect and ripple pulsation, obtain higher Q value simultaneously.

3. pair WDM signal is transparent.The CS-RZ signal of WDM, the NRZ signal obtained after directly carrying out pattern conversion by the present invention or WDM signal, the process of additional demultiplexing, does not need to add the wavelength division multiplexers such as AWG yet and carries out multiplexingly just can directly transmitting in a wdm system.

4. possesses multichannel translation function simultaneously: construct a multichannel fiber grating and can realize the conversion of multi channel CS-RZ to NRZ pattern simultaneously, such as, emulation experiment adopts 4 channels.

5. full raster non-active operation mode, energy-conserving and environment-protective, stable performance, without additional noise, with existing optical fiber telecommunications system highly compatible.

Accompanying drawing explanation

Fig. 1 is ultimate principle figure of the present invention;

Fig. 2 is the power spectrum of CS-RZ signal;

Fig. 3 is the figure of CS-RZ power spectrum signal through the cutting of fiber grating spectrum;

Fig. 4 is the power spectrum of NRZ;

Fig. 5 is CS-RZ, NRZ pattern power spectrum comparison diagram;

Fig. 6 is fiber grating characteristic spectrum cutting schematic diagram and filtering order optimization figure.

Fig. 7 is the change curve of conversion gained NRZ pattern Q value with filtering order;

Fig. 8 is the change curve of standard deviation with filtering order of conversion gained NRZ pattern 1 yard;

Fig. 9 is index modulation function and the local chirp value of fiber grating; .

Figure 10 is the comparison diagram of object penetrating spectrum and simulated transmission spectrum;

Figure 11 is the oscillogram of the CS-RZ signal of 20Gbit/s;

Figure 12 is the transmission spectrum of the fiber grating of the CS-RZ signal input of 20Gbit/s;

Figure 13 is after the CS-RZ signal input of 20Gbit/s, the oscillogram of the NRZ of output;

Figure 14 is after the CS-RZ signal input of 20Gbit/s, the eye pattern of NRZ after conversion;

Figure 15 is 40Gbit/s full light CS-RZ to NRZ code type conversion apparatus schematic diagram in embodiment two;

Figure 16 is the eye pattern of the NRZ pattern signal after the full light CS-RZ of 40Gbit/s changes;

Figure 17 is the reflectance spectrum of 4 channel fiber gratings;

Figure 18 is index modulation function and the local chirp value of 4 channel 40Gbit/s full light CS-RZ to NRZ pattern upconversion fiber grating.

Embodiment

Describe the present invention in detail below in conjunction with accompanying drawing and specific implementation method, be used for explaining the present invention in exemplary embodiment and description of the present invention, but not as a limitation of the invention.

As shown in Figure 1, passive CS-RZ to NRZ full optical code type conversion apparatus based on blade type spectral response fiber grating of the present invention is used for the NRZ signal CS-RZ signal to be converted of setting signal speed being converted to same signal rate, comprise the fiber grating with blade type spectral response, it is made up of fiber grating main body 2 and grating first port one and grating second port 3 two ports.The spectral response of described fiber grating main body, namely transmission spectrum or reflectance spectrum are the spectral composition features of the spectral composition of CS-RZ signal to be converted according to special speed and the NRZ signal of corresponding bits speed, select wavelength centered by one of CS-RZ frequency spectrum two sidebands, i.e. relative carrier frequency red shift or frequency corresponding to blue shift 1/2nd bit rate, calculate the difference of NRZ power spectrum and CS-RZ power spectrum, according to the difference of power spectrum about the asymmetric line of centre wavelength, different disposal method is taked to carry out respectively designing and obtain in the centre wavelength left and right sides.Here special speed refers to that speed is more than or equal to 10Gbit/s, and is less than or equal to the CS-RZ signal of 200Gbit/s.Refractive index modulation distribution and the distribution of warbling of fiber grating main body are obtained by spectral response inverting according to cause-effect relationship, and fiber grating can adopt publicly-owned method to carry out inscribing and making.

As shown in Figure 1, CS-RZ signal to be converted enters grating first port one, by fiber grating main body 2, from the angle analysis of frequency domain, fiber grating main body 2 is just equivalent to a wave filter, its blade type spectral response, namely the frequency spectrum of the CS-RZ signal to be converted to described special speed is carried out cutting by transmission spectrum or reflectance spectrum, cutting center obtains different cutting amounts for certain sideband of selected CS-RZ frequency spectrum, the left and right sides, and cutting amount size is determined by blade type spectral response.Complete Spectrum Conversion by a cutting of blade type spectral response, realize the adjustment of pulse shape in time domain, complete pattern conversion, obtain NRZ signal.If described blade type spectral response is the transmission spectrum of fiber grating, transmitted light contains the NRZ signal that pattern is converted to, and described NRZ signal exports from grating second port 3.Otherwise if described blade type frequency spectrum should be the reflectance spectrum of fiber grating, then reflected light contains the NRZ signal that pattern is converted to, described NRZ signal exports from institute's grating first port one.As shown in Figure 2, it is the power spectrum of the CS-RZ signal that CS-RZ signal inputs from grating first port one.As shown in Figure 3, the situation of CS-RZ signal optical fiber grating spectrum cutting when fiber grating main body 2, black dotted lines represents the characteristic spectrum of fiber grating.As shown in Figure 4, it is the power spectrum of the NRZ exported from grating second port 3 of fiber grating.

The blade type transmission spectrum of fiber grating or reflectance spectrum are spectral compositions according to special speed CS-RZ signal to be converted, the spectral composition of the NRZ signal of centre wavelength red shift or blue shift and corresponding bits speed designs.The spectrum of CS-RZ signal to be converted of input, because carrier wave is suppressed, does not have obvious line spectrum at carrier wave place, but each side there is a very strong line spectrum at carrier wave, and be called the sideband of CS-RZ code, the difference on the frequency between two sidebands equals bit rate.The spectrum of NRZ code comprises continuous spectrum part and the very strong discrete line spectrum at carrier wave place, and at the frequency place of bit rate integral multiple, remaining line spectrum, compared with the line spectrum at carrier wave place, much weak.The difference that the spectral composition of CS-RZ and NRZ signal is maximum has the spectrum carrier wave of two point: 1.CS-RZ suppressed, there are two very strong sidebands, i.e. two very strong discrete line spectrums, and only there is a very strong discrete line spectrum at carrier wave place in NRZ spectrum, single order sideband is very weak, negligible.2., after centre wavelength red shift or blue shift, the spectrum of CS-RZ loses bilateral symmetry, and the spectrum of NRZ is symmetrical.

Fiber grating of the present invention is as a bandpass filter, and distinguish greatly for two of the two spectrum and design, retained by the sideband of in CS-RZ frequency spectrum, another one sideband filters out.Centered by the sideband of selected reservation, CS-RZ frequency spectrum after centre wavelength red shift or blue shift and the NRZ frequency spectrum centered by carrier wavelength are compared, obtain the filter curve that the centre wavelength left and right sides is different separately, thus obtain the blade type spectral response curve of fiber grating.Optimal design shows, the pattern conversion effect that first-order filtering obtains is optimum.

The structural parameters of fiber grating of the present invention, namely Refractive index modulation distribution and distribution of warbling are obtained by spectral response inverting according to the cause-effect relationship between optical grating construction and spectral response.Spectral response is the concrete manifestation of fiber grating filtering characteristic, and its essence is uniquely determined by optical fiber grating structure, the two Satisfying Causality relation.Therefore, determine required spectral response, according to known algorithm, just can calculate the whole structural parameters of grating according to spectral response.Just can adopt publicly-owned method according to Refractive index modulation distribution and distribution of warbling, such as point-to-point writing method carries out inscribing and making, thus obtains fiber grating of the present invention.

Provide the design process of fiber grating spectral response below:

Embodiment one:

Below for a kind of single channel 20Gbit/s full light CS-RZ to NRZ pattern conversion designs method.

The first step: a given group code stream length is 2 ⁿthe pseudo-random code of-1, when the dutycycle, the signal rate that provide 67% according to publicly-owned method are 20Gbit/s, the discretize numeral of CS-RZ code and NRZ code describes, i.e. discretize sequence of values S _cS-RZ(t) and S _nRZ(t).

Second step: to S _cS-RZ(t) and S _nRZt () these two groups of discretize sequence of values do fast fourier transform, in units of decibel, obtain the discretize sequence of values SPCT of the two power spectrum _{org_CS-RZ}(Δ λ) and SPCT _nRZ(Δ λ).As shown in Figure 5, solid line represents SPCT _nRZ(Δ λ), dotted line represents SPCT _{org_CS-RZ}(Δ λ)), that is:

S_FFT _CS-RZ＝FFT(S _CS-RZ(t))

S_FFT _NRZ＝FFT(S _NRZ(t))

SPCT _{org_CS-RZ}(Δλ)＝10*log(S_FFT _CS-RZ×S_FFT _CS-RZ ^*/T)

SPCT _NRZ(Δλ)＝10*log(S_FFT _NRZ×S_FFT _NRZ ^*/T)

Wherein S_FFT _cS-RZ ^*for S_FFT _cS-RZcomplex conjugate, S_FFT _nRZ ^*for S_FFT _nRZcomplex conjugate, T is the time to chopping determined by code stream length, Δ λ=λ-λ _c, λ _ccentered by wavelength and carrier wavelength.

3rd step: by the SPCT of CS-RZ signal _{org_CS-RZ}(Δ λ) centre wavelength blue shift or red shift obtain CS-RZ signal spectrum SPCT after centre wavelength blue shift or red shift _cS-RZ(Δ λ).Wherein B _1rdfor wavelength width corresponding when signal bit rate is converted in units of nm, the bandwidth namely between CS-RZ frequency spectrum two sidebands, when signal bit rate is 20Gbit/s, B _1rd=0.16nm.Even:

${\mathrm{SPCT}}_{CS-RZ}\left(\mathrm{\Δ}\mathrm{\λ}\right)={\mathrm{SPCT}}_{org\_CS-RZ}(\mathrm{\Δ}\mathrm{\λ}\±\frac{1}{2}{B}_{1rd})$

Wherein, positive sign and negative sign correspond to blue shift and red shift respectively.In Fig. 6, solid line provides the situation of centre wavelength blue shift, designs below for blue shift, and for the situation of red shift, the flow process with reference to blue shift carries out processing, and does not repeat them here.

4th step: with the discretize sequence of values SPCT of NRZ power spectrum _nRZ(Δ λ) deducts CS-RZ blue shift the discretize sequence of values SPCT of power spectrum _cS-RZ(Δ λ), obtains one group of new discretize sequence of values SPCT _nRZ-CS-RZ(Δ λ), as shown in phantom in Figure 6.The centre wavelength left and right sides of Fig. 6 is asymmetric, SPCT _grtand SPCT _grtaccording to asymmetrical SPCT _nRZ-CS-RZthe left and right sides is designed respectively, overall formation blade type spectral response.

That is:

SPCT _NRZ-CS-RZ(Δλ)＝SPCT _NRZ(Δλ)-SPCT _CS-RZ(Δλ)

5th step: according to the difference SPCT of power spectrum _nRZ-CS-RZ(Δ λ) near centre wavelength ± B _1rdvalue condition in (± 0.16nm) scope, about point, two parts process.Left-half SPCT _nRZ-CS-RZbe greater than zero, as wave filter, because not possessing the function of power amplification, its transmitance or reflectivity all can not more than 0dB, therefore the left-half of fiber grating characteristic spectrum is designed to a value close to 0dB; Right half part SPCT _nRZ-CS-RZbe less than zero, can directly as a part for fiber grating characteristic spectrum.Choosing cutting width is like this ± B _1rdcrop window to SPCT _nRZ-CS-RZcarry out cutting, obtain the characteristic spectrum SPCT that fiber grating is complete _grt, for 20Gbit/sCS-RZ code, B _1rd=0.16nm, obtains characteristic spectrum SPCT _grtas shown in solid line in Fig. 6:

$\left\{\begin{array}{cc}{\mathrm{SPCT}}_{grt}\left(\mathrm{\&Delta;}\mathrm{\&lambda;}\right)={\mathrm{SPCT}}_{NRZ-CS-RZ}\left(\mathrm{\&Delta;}\mathrm{\&lambda;}\right)& 0\&le;\mathrm{\&Delta;}\mathrm{\&lambda;}\&le;B_{1rd}\\ {\mathrm{SPCT}}_{grt}\left(\mathrm{\&Delta;}\mathrm{\&lambda;}\right)=-0.01dB& -B_{1rd}\&le;\mathrm{\&Delta;}\mathrm{\&lambda;}<0\\ {\mathrm{SPCT}}_{grt}\left(\mathrm{\&Delta;}\mathrm{\&lambda;}\right)=-40dB& \mathrm{\&Delta;}\mathrm{\&lambda;}\&le;-B_{1rd}\\ {\mathrm{SPCT}}_{grt}\left(\mathrm{\&Delta;}\mathrm{\&lambda;}\right)=-40dB& \mathrm{\&Delta;}\mathrm{\&lambda;}\&GreaterEqual;B_{1rd}\end{array}\right.$

That is: in cutting window, 0≤Δ λ≤B _1rdregion, make SPCT _grt(Δ λ)=SPCT _nRZ-CS-RZ(Δ λ), at-B _1rdin the region of≤Δ λ <0, the left-half of characteristic spectrum is designed to a value close to 0dB, makes SPCT _grt(Δ λ)=-0.01dB; SPCT is made outside window in cutting _grt(Δ λ) be one close to zero small value (-40dB), but can not zero be got, so that next step Grating Design and physics realization.A kind of blade type spectral response is obtained like this in crop window, show by optimizing calculating, utilize the fiber grating with this blade type spectral response to carry out first-order filtering and just can obtain best filter effect, this has been the spectral response that the conversion of CS-RZ to NRZ pattern is best.

Fig. 7 and Fig. 8 is respectively the standard deviation of conversion gained NRZ pattern Q value and 1 yard with the change curve of filtering order, in figure, curve illustrates that first-order filtering can obtain maximum Q value and minimum 1 yard of standard deviation respectively, namely adopt first-order filtering, can well pattern effect be suppressed while the maximum Q value of acquisition.

As everyone knows, if the NRZ signal obtained after needing conversion exports from grating first port, then the reflectance spectrum r of fiber grating is made ²(Δ λ) equals characteristic spectrum SPCT _grt(Δ λ), otherwise, if the NRZ signal obtained after needing conversion exports from the second port of fiber grating, then make the transmission spectrum t of fiber grating ²(Δ λ) equals characteristic spectrum SPCT _grt(Δ λ), even:

10*log (r ²(Δ λ))=SPCT _grtfirst port of (Δ λ) then grating is output terminal

Or 10*log (t ²(Δ λ))=SPCT _grtsecond port of (Δ λ) then grating is output terminal

Wherein t ²(Δ λ)+r ²(Δ λ)=1.

6th step: according to the characteristic spectrum SPCT of fiber grating _grt(Δ λ), adopts such as discrete reverse layer strip etc. to design the structure of grating.Refractive index modulation distribution as shown in Figure 9 and distribution of warbling, complete Grating Design process.As shown in Figure 10,

The CS-RZ signal to be converted of 20Gbit/s code type conversion apparatus of the present invention enters grating first port one, through fiber grating main body 2, the frequency spectrum of CS-RZ signal to be converted is subject to the cutting of fiber grating transmission spectrum, Spectrum Conversion is completed by a cutting, realize pulse strenching, complete pattern conversion, obtain the NRZ signal of 20Gbit/s and export from grating second port 3, NRZ signal relative CS-RZ signal center wavelength blue shift wherein B _1rdfor wavelength width corresponding when signal bit rate is converted in units of nm, the bandwidth namely between CS-RZ frequency spectrum two sidebands, when signal bit rate is 20Gbit/s, B _1rd=0.16nm.Figure 11 is the waveform of the CS-RZ pattern signal of input, and Figure 12 is the transmission spectrum of fiber grating, and Figure 13 is the waveform of the NRZ pattern signal exported, and Figure 14 is the eye pattern of NRZ pattern signal.The transmission spectrum of this fiber grating designs according to the difference of both 20Gbit/sCS-RZ signal spectrum and 20Gbit/sNRZ signal spectrum, according to the requirement eliminating 20Gbit/sCS-RZ flashlight spectrum distance carrier wave+0.16nm place sideband, its bandwidth Design is 0.32nm, ± 0.16nm place provides the filter effect being greater than 40dB, reaches the object of pattern conversion.After conversion, as shown in figure 14, eye pattern opens greatly the eye pattern of NRZ pattern signal, and Q value is 64.39.

Embodiment two

Below for a kind of multichannel 40Gbit/s full light CS-RZ to NRZ pattern conversion designs method.As shown in figure 15, circulator 4 comprises A, B, C tri-ports to its device, and fiber grating comprises grating first port one and grating second port 2 two ports.WDM CS-RZ signal to be converted inputs from the A port of circulator 4, export from circulator C port, enter grating first port one, export from grating first port one after the reflection of fiber grating main body, circulator is entered from circulator C port, and export from circulator B port, obtain 40Gbit/sWDMNRZ signal.Figure 16 is the eye pattern of NRZ pattern signal after conversion, and Figure 17 is the reflectance spectrum of 4 channel fiber gratings.Because the signal after pattern conversion exports, so characteristic spectrum is here the reflectance spectrum of fiber grating from grating first port one.The characteristic spectrum (reflectance spectrum) of this fiber grating designs according to difference left and right two parts of both 40Gbit/sCS-RZ signal center wavelength blue shift 0.16nm gained spectrum and 40Gbit/sNRZ signal spectrum, according to the requirement eliminating 40Gbit/sCS-RZ flashlight spectrum distance carrier wave+0.32nm place sideband, each channel width is designed to 0.60nm, the filter effect being greater than 40dB is provided at ± 0.32nm place, channel spacing is taken as 1.6nm (corresponding 200GHz) to eliminate the crosstalk of interchannel, reaches the object of pattern conversion.After conversion, as shown in figure 16, eye pattern opens greatly the eye pattern of NRZ pattern signal, and calculate and obtain, Q value is 53.68.

Wherein the number of channel need be only 4 by the design of 4 channel fiber gratings, each channel width gets 0.60nm, dutycycle gets 50%, channel spacing gets 1.6nm (corresponding 200GHz), according to the fiber grating design procedure provided in above-described embodiment 1, carry out with reference to publicly-owned multichannel optical fiber grating design method, do not repeat them here.Figure 18 provides 4 channels, the optical grating construction of 40Gbit/s full light CS-RZ to the NRZ pattern upconversion fiber grating of channel spacing 200GHz, and it comprises index modulation function and local chirp value.

Above the technical scheme that the embodiment of the present invention provides is described in detail, apply specific case herein to set forth the principle of the embodiment of the present invention and embodiment, the explanation of above embodiment is only applicable to the principle helping to understand the embodiment of the present invention; Meanwhile, for one of ordinary skill in the art, according to the embodiment of the present invention, embodiment and range of application all will change, and in sum, this description should not be construed as limitation of the present invention.

Claims (4)

1. CS-RZ to a NRZ pattern upconversion fiber grating design method, is characterized in that, comprise the following steps:

A given group code stream length is 2 ⁿthe pseudo-random code of-1, provides the discretize sequence of values of CS-RZ code and NRZ code when dutycycle is certain value, signal rate is definite value;

Fast fourier transform is done to two groups of discretize sequence of values, in units of decibel, obtains the discretize sequence of values of the two power spectrum;

By wavelength width corresponding for the bit rate of the centre wavelength blue shift of the discretize sequence of values of the power spectrum of CS-RZ signal or red shift half CS-RZ signal, obtain the CS-RZ signal spectrum after centre wavelength blue shift or red shift;

One group of new discretize sequence of values is obtained with the CS-RZ signal spectrum after the discretize sequence of values of NRZ power spectrum deducts blue shift or red shift;

Choosing cutting width is that the crop window of the wavelength width that the bit rate of two CS-RZ signals is corresponding carries out cutting to new discretize sequence of values, obtains the characteristic spectrum that fiber grating is complete;

According to the characteristic spectrum of fiber grating, adopt and comprise the structure that discrete reverse layer strip obtains grating.

2. CS-RZ to the NRZ pattern that method for designing design according to claim 1 obtains transforms fiber grating device, for the CS-RZ signal to be converted of setting signal speed being converted to the NRZ signal of same signal rate, it is characterized in that: comprise the fiber grating with blade type spectral response, it is made up of fiber grating main body and grating first port and grating second port two ports.

3. CS-RZ to NRZ pattern according to claim 2 transforms fiber grating device, it is characterized in that: also comprise a circulator, described circulator is connected with fiber grating, CS-RZ signal to be converted enters from circulator, be back to circulator after entering into fiber grating again, and export from circulator.

4. CS-RZ to NRZ pattern according to claim 2 transforms fiber grating device, it is characterized in that: described signal rate is more than or equal to 10Gbit/s, and is less than or equal to 200Gbit/s.