CN1208640C - Device capable of simultaneously realizing optical filtering and dispersion compensation function - Google Patents

Abstract

The present invention relates to a device which is capable of realizing the functions of optical wave filtration and chromatic dispersion compensation simultaneously. The present invention comprises an optical input end and an optical output end, wherein a device which is capable of filtering waves and compensating chromatic dispersion simultaneously is arranged between the optical input end and the optical output end. The present invention is characterized in that the device which is capable of realizing the functions of optical wave filtration and chromatic dispersion compensation simultaneously is formed by connecting a coupling type device with multiple-port optical directions, and a chirp optical fiber grating. The present invention can simultaneously filter optical waves and compensate chromatic dispersion and has the following steps: signal light with multiple wavelength is provided, and certain undistorted signal light with specific wavelength needs to be obtained; the signal light with multiple wavelength is transmitted to the device which is capable of filtering waves and compensating chromatic dispersion simultaneously; when the device extracts the signal light with a preset wave band, the device compresses pulse widening to compensate chromatic dispersion. Consequently, undistorted preset signal light can be simultaneously output from the device which is capable of filtering waves and compensating chromatic dispersion.

Description

Can realize the device of optically filtering and chromatic dispersion compensating function simultaneously

Technical field

The invention belongs to the optic communication device field, the particularly a kind of device that can realize optically filtering and chromatic dispersion compensating function simultaneously.

Background technology

For satisfying growing communication system volume expansion needs, make full use of the enormous bandwidth resource of optical fiber, dense wave division multipurpose (Dense Wavelength Division Multiplexing, DWDM) technology is as the preferred plan of current optical fiber telecommunications system dilatation, its development trend will be higher rate, longer distance, high capacity more, be in particular in that every road wavelength multiplexing number increases in the communication system, channel spacing reduces.

This high speed DWDM transmission system proposes requirements at the higher level to device performance, and the communication device that look for novelty can promote higher spectrum efficiency, has stronger dirigibility and lower cost.Wave filter will have high reflectance, narrow bandwidth as the Primary Component in the system on narrow channel spacing basis, good channel isolation, and lower insertion loss, less crosstalks and higher bandwidth availability ratio.Because square being inversely proportional to of the dispersion tolerance of system and signal rate, high speed transmission system is also more and more higher to the requirement that chromatic dispersion is controlled, and just must carry out accurate and effective dispersion compensation after transmitting more short distance.

At present, in the dwdm system general filtering technique mainly contain multilayer dielectric film filtering, array waveguide grating (Array Waveguide Grating, AWG) and optical fiber Bragg raster (Fiber BraggGrating, FBG).

Multilayer thin-film-filter is made up of the multilayer highly reflecting films, is a kind of wave filter that utilizes the multiple-beam interference principle to make.Temperature characterisitic is relatively good, and passband is more smooth, has the good optical characteristic aspect isolation, polarization loss and the polarization mode dispersion.

Array waveguide grating is the plane waveguiding device based on the light integrated technology, also is the filtering device that utilizes the beam interference principle to make.Owing to adopt the slab guide technology, have compact conformation, be easy to produce characteristics such as good reproducibility in batches.

Optical fiber Bragg raster is a kind of full optical fibre device.It utilizes the photosensitivity of optical fiber, and the irradiation by ultraviolet light makes the refractive index of fiber core produce periodic disturbance, has formed the reverberator with wavelength selectivity.The modulate intensity of the cycle of fiber grating, length and refractive index has determined the height of optical grating reflection rate and the size of bandwidth together.The online optical fiber filter that utilizes the wavelength selectivity of FBG to make have cost low, with the optical fiber compatibility, be easy to advantages such as integrated, can realize narrow channel filtering.

Aspect dispersion compensation, the employed Transmission Fibers of dwdm system all is single-mode fiber usually, its chromatic dispersion can be divided into chromatic dispersion (be group velocity dispersion, Group Velocity Dispersion, GVD) and polarization mode dispersion (Polarization Mode Dispersion, PMD).For chromatic dispersion compensation, at present common solution have the employing dispersion compensating fiber (Dispersion Compensated Fiber, DCF) and chirped fiber grating (Chirped Fiber Bragg Grating, CFBG) two kinds.

DCF is a kind of single-mode fiber with big negative dispersion, little core size, can carry out dispersion compensation.But, because the attenuation coefficient of DCF is also big more to the additional attenuation that system introduces than long DCF when chromatic dispersion compensation quantity is big than the general single mode fiber height, need extra these losses that compensate, increased system cost.When DCF is used for wavelength-division multiplex system in addition, be easy to generate nonlinear effect, make to produce between signal and crosstalk.

CFBG refers to the FBG that the grating cycle changes a lot along its length.Adopt CFBG to carry out accurate dispersion compensation to each channel easily, its compensation ability is strong, and cost is low, to the upgrading of optical fiber link also than being easier to.Have that added losses are little, characteristic such as device miniatureization, coupling are good.

In optical fiber telecommunications system, in order to extract distortionless using light signal, usually adopt dispersion compensation device that signal is carried out dispersion compensation at present earlier, after the shaping pulse, extract signal with filtering device again, wherein, employed dispersion compensation device and filtering device generally all adopt foregoing known technology.Though this mode that adopts two kinds of individual devices to realize dispersion compensations and filter function respectively can meet the demands, because that device uses is muptiple-use and individual different in nature, it is bigger to have an insertion loss, the more high deficiency of cost.

Summary of the invention

The purpose of this invention is to provide a kind of device that can realize optically filtering and chromatic dispersion compensating function simultaneously, it can distortionlessly leach predetermined light signal, can provide a certain amount of chromatic dispersion to predetermined light signal again, give dispersion compensation, make device when leaching light signal, carry out dispersion compensation, and it is little to insert loss, and cost is low, to overcome above-mentioned deficiency.

To achieve these goals, the scheme that the present invention adopts is: a kind of device that can realize optically filtering and chromatic dispersion compensating function simultaneously, comprise light input end, light output end, the device that can carry out filter and dispersion compensation is simultaneously arranged between light input end and light output end, the light input, output terminal is provided by multiport light direction coupled mode device, chirped fiber grating is as the device that carries out filter and dispersion compensation simultaneously, be characterized in: an input end of multiport light direction coupled mode device is as the light input end of whole optical device, an one output terminal is as the light output end of whole optical device, and an one input/output terminal connects chirped fiber grating.

The step that can carry out optically filtering and dispersion compensation simultaneously is as follows:

A plurality of wavelength signals light are provided, need obtain the distortionless flashlight of some specific wavelength; To the device that can realize filter and dispersion compensation simultaneously, this device is when extracting the predetermined band signal with these multi-wavelength signals light transmission, and the compression pulse broadening carries out dispersion compensation; The distortionless prearranged signals light of output from the device that can realize filter and dispersion compensation simultaneously.

In such scheme, chirped fiber grating is as critical component, and its filtering performance and dispersion compensation characteristic are determined by its characteristic curve (reflectance spectrum and time lag curve).According to of the requirement of high speed DWDM transmission system to filter and dispersion compensation, chirped fiber grating is wanted to realize this two kinds of functions simultaneously, its reflectance spectrum and time lag curve are all had high requirements, reflectance spectrum must be on narrow channel spacing basis, have high reflectance, narrow bandwidth and higher bandwidth availability ratio, time lag curve will have the good smoothness and the linearity simultaneously.The grating of the different structure curve that takes on a different character.For obtaining high performance characteristic curve, must design specific optical grating construction with the requirement that touches the mark.

The structural design of grating refers to design grating structural parameter according to the target signature curve.Usually describe the architectural feature of chirped fiber grating with apodizing function Δ n (z) and local chirp value Λ (z), z represents the optical grating axial location parameter.As Λ (z) when being linear function, the form of warbling of grating is for linear; The Λ of nonlinearly chirped fiber grating (z) is a nonlinear function.Typical apodizing function has Gaussian function, hyperbolic tangent function, cosine function and raised cosine etc., and their function curve all is the bell of symmetry.Though the CFBG reflectance spectrum after these functions are cut toe becomes smooth, delay variation makes moderate progress, and reflectivity is lower, and bandwidth availability ratio is not high, and the time lag curve smoothness is relatively poor, and the linearity is good inadequately.Thus, must select for use a kind of effective method for designing could guarantee that the chirped fiber grating filtering characteristic is good, the dispersion compensation ability is good, insert a little less than the little and nonlinear effect of loss.

Better simply fiber Bragg grating design method is a single order Born approximation method, utilize Fourier transform relation approximate between optical grating reflection spectrum and coupling coefficient to obtain grating structural parameter, this method only is applicable to the antiradar reflectivity grating, has limitation when design high reflectance grating.Another kind of method adopts the integral equation with exact solution to describe electromagnetic wave propagation characteristic in the grating, by solving equation, obtains grating structural parameter.But be difficult for obtaining the equation analytic solution usually, need the target spectrum is carried out the rational function restriction or taked specific mathematics derivation algorithm, this class methods counting yield is lower, and accuracy is relatively poor as a result.

In addition, also has a kind of grating method for designing of discussing based on cause and effect, from the optical gate matrix analytic approach, grating is divided into multilayer, take into full account the structure and the physical characteristics of electromagnetic wave propagation dielectric layer, on the scene when propagating along grating, according to simple cause-effect relationship, successively determine each layer dielectric structure parameter.This method has advantages such as counting yield height, result be accurate.The analytical characteristic curve and the target signature curve that the analysis showed that the grating of this method design of employing overlap substantially, so in the theory design, can obtain structural parameters high-quality, dominance energy optical fiber Bragg raster by setting good target signature curve.

The making of chirped fiber grating can be adopted multiple known method, as phase mask method, optical fiber/mask motion scan method, re-expose method or the like.For the chirped fiber grating among the present invention, as previously mentioned, its structural parameters are to require to carry out obtaining after the individual design according to concrete filter and dispersion compensation, and the difference of target component, the structure of grating are also different.For reducing cost of manufacture, can select for use optical fiber/mask motion scan legal system to make the chirped fiber grating among the present invention, this method is easy to realize, and conveniently, flexibly, is convenient to control.

Description of drawings

Fig. 1 is the schematic diagram of chirped fiber grating.

Fig. 2 is characteristic curve (reflectance spectrum and the time lag curve) figure of chirped fiber grating.

Fig. 3 is the method for designing key diagram of chirped fiber grating.

Fig. 4 is structural parameters figure and the characteristic curve diagram according to the chirped fiber grating of a target index Design.

Fig. 5 is a technical scheme of the present invention.

Fig. 6 is indefiniteness embodiment one of the present invention.

Fig. 7 is indefiniteness embodiment two of the present invention.

Fig. 8 is indefiniteness embodiment three of the present invention.

Embodiment

With reference to the accompanying drawings, describe the principle that the present invention adopts in detail, illustrate the critical component among the present invention simultaneously---the method for designing of chirped fiber grating and according to the chirped fiber grating structural parameters of target index Design, and technical scheme of the present invention, and come to describe more lucidly above-mentioned purpose of the present invention and advantage in conjunction with three indefiniteness embodiment.

With reference to Fig. 1, critical component---the schematic diagram of chirped fiber grating among signal the present invention.In chirped fiber grating, reflection wavelength (being resonance wavelength) in the reflection bandwidth is the function of fiber grating position, promptly the every bit along fiber grating all has a local Bragg wavelength, so the light of different wave length reflects on the diverse location of chirped fiber grating and has different time delays.As shown in the figure, long wavelength's component of wave travels is reflected at the initiating terminal of grating in the optical fiber, the short wavelength components of wave travels is in the far-end reflection of grating, be that light wave is through behind the grating, the time delay longer wavelength light of short-wavelength light the time prolong, so just compensated the short wavelength components that chromatic dispersion caused preceding, long wavelength's component after situation.Therefore chirped fiber grating can play the effect of dispersion equilibrium, realizes dispersion compensation.Because chirped fiber grating is that wavelength in the reflection bandwidth is carried out dispersion compensation, so can utilize chirped fiber grating to realize filter and dispersion compensation simultaneously.

With reference to Fig. 2, characteristic curve (reflectance spectrum and the time lag curve) figure of the critical component among signal the present invention---chirped fiber grating.As shown in the figure, the reflectance spectrum of chirped fiber grating has certain bandwidth, and has certain time delay in the band, is equivalent to a bandpass filter with certain dispersion measure, shows that chirped fiber grating not only has wavelength selectivity, and can carry out dispersion compensation simultaneously.

The chirped fiber grating of the different structure curve that takes on a different character also just has different filter and dispersion compensation characteristics.Chirped fiber grating among the figure is a linear chirp optical fiber grating of cutting toe through Gaussian function, and the characteristic curve of this grating is unsatisfactory as seen from the figure.For making grating have filtering performance and dispersion compensation ability preferably, must choose effective grating method for designing, to obtain the desired characteristics curve.

With reference to Fig. 3, the critical component among illustrative the present invention---the method for designing that chirped fiber grating adopted.

Grating discrete model in Fig. 3 a illustrative optical gate matrix analytic approach, grating is divided into the M section, and every segment length is a Δ, is similar to think that each section all is a uniform dielectric, then along with the increase of segments M, the M section uniform dielectric of available refractive index step approaches continuous index distribution.Use respectively R (z, δ), S (z, δ) the gradual amplitude of expression forward direction and back-propagating field, the coupling coefficient q between the two _i(z) (i=1,2 ... M) be constant in uniform dielectric, then the matrix form of expression that propagate i section field among the figure is:

$\left[\begin{array}{c}{R}_{i+1}(z+\mathrm{\Δ},\mathrm{\δ})\\ S_{i+1}(z+\mathrm{\Δ},\mathrm{\δ})\end{array}\right]=T_i\·\left[\begin{array}{c}{R}_i(z,\mathrm{\δ})\\ S_i(z,\mathrm{\δ})\end{array}\right]---\left(1\right)$

T in the formula _iExpression formula be:

$T_i=\left[\begin{array}{cc}\mathrm{ch}\left({\mathrm{\γ}}_{B_i}\mathrm{\Δ}\right)-i\frac{\mathrm{\δ}}{{\mathrm{\γ}}_{B_i}}\mathrm{sh}\left({\mathrm{\γ}}_{B_i}\mathrm{\Δ}\right)& \frac{q_i\left(z\right)}{{\mathrm{\γ}}_{B_i}}\mathrm{sh}\left({\mathrm{\γ}}_{B_i}\mathrm{\Δ}\right)\\ \frac{q_i{\left(z\right)}^{*}}{{\mathrm{\γ}}_{B_i}}\mathrm{sh}\left({\mathrm{\γ}}_{B_i}\mathrm{\Δ}\right)& \mathrm{ch}\left({\mathrm{\γ}}_{B_i}\mathrm{\Δ}\right)+i\frac{\mathrm{\δ}}{{\mathrm{\γ}}_{B_i}}\mathrm{sh}\left({\mathrm{\γ}}_{B_i}\mathrm{\Δ}\right)\end{array}\right]---\left(2\right)$

Wherein, $\mathrm{\δ}={2\mathrm{\πn}}_{\mathrm{eff}}(\frac{1}{\mathrm{\λ}}-\frac{1}{{\mathrm{\λ}}_b}),$ n _EffBe effective refractive index, λ _bBe Bragg reflection kernel wavelength; ${{\mathrm{\γ}}_{B_i}}^2={\left|q_i\left(z\right)\right|}^2-{\mathrm{\δ}}^2;$ q _i(z) be coupling coefficient, and the relation between the grating structural parameter is

$q_i\left(z\right)=\frac{\mathrm{\π\Δn}\left(z\right)}{\mathrm{\λ}}{e}^{-j[\frac{\mathrm{\π}}{2}+\mathrm{\θ}\left(z\right)]}---\left(3\right)$

Matrix T _iThe propagation characteristic of light field in i section grating after the sign raster-segment discretize.Below further to matrix T _iBe similar to.

Shown in Fig. 3 b, regard this section grating as an independently interflection device, the complex reflection coefficient of establishing the reverberator left and right is respectively ρ _i,-ρ _i ^*, then the transmission matrix of this reverberator is:

$T_{{\mathrm{\ρ}}_i}={(1-{\left|{\mathrm{\ρ}}_i\right|}^2)}^{-1/2}\left[\begin{array}{cc}1& {{-\mathrm{\ρ}}_i}^{*}\\ -{\mathrm{\ρ}}_i& 1\end{array}\right]---\left(4\right)$

Simultaneously, with position phase matrix T _{Δ i}Characterize the clean propagation of reverberator midfield, be expressed as:

$T_{{\mathrm{\Δ}}_i}=\left[\begin{array}{cc}\exp \left(\mathrm{i\δ\Δ}\right)& 0\\ 0& \exp -\left(\mathrm{i\δ\Δ}\right)\end{array}\right]---\left(5\right)$

Use T _{ρ i}GT _{Δ i}The approximate T that replaces _i, then have by formula (1):

$\left[\begin{array}{c}{R}_{i+1}(z+\mathrm{\Δ},\mathrm{\β})\\ S_{i+1}(z+\mathrm{\Δ},\mathrm{\β})\end{array}\right]=T_i\·\left[\begin{array}{c}{R}_i(z,\mathrm{\β})\\ S_i(z,\mathrm{\β})\end{array}\right]\≈T_{{\mathrm{\ρ}}_i}g{T}_{{\mathrm{\Δ}}_i}g\left[\begin{array}{c}{R}_i(z,\mathrm{\β})\\ S_i(z,\mathrm{\β})\end{array}\right]---\left(6\right)$

T wherein _{ρ i}Complex reflection coefficient ρ _iExpression formula be:

${\mathrm{\ρ}}_i=-\tanh \left(\right|q_i\left|\mathrm{\Δ}\right)\frac{{q_i}^{*}}{\left|q_i\right|}---\left(7\right)$

Therefore, grating is regarded as the interflection device P that is spaced apart Δ by a series of ₁, P ₂P _MCascade constitutes, and this is a cause and effect, stable linear system.According to the causality discussion, this constantly input constantly and before this, then i interflection device P is only depended in system's output constantly _iImpulse response when time t=0 and reverberator P _j(so j＞i) irrelevant is P _iComplex reflection coefficient ρ _iCan be by r _i(δ)=R _i(δ)/S _i(δ) the inverse fourier transform F when time t=0 ^-1[r _i(δ)] _T=0Calculate, thereby obtain T _{ρ i}, T _{Δ i}Utilize matrix again $T_i\≈T_{{\mathrm{\ρ}}_i}g{T}_{{\mathrm{\Δ}}_i}$ The field is transferred to the i+1 section grating of discretize, calculate r _I+1(δ)=R _I+1(δ)/S _I+1(δ), to r _I+1(δ) make inverse fourier transform F ^-1[r _I+1(δ)] _T=0, obtain ρ _I+1By this process, on the scenely carry out piecemeal when propagating along grating, obtain ρ successively ₁, ρ ₂... ρ _MAccording to formula (7), calculate coupling coefficient q at last ₁, q ₂... q _M, obtain grating structural parameter by formula (3).This computation process of Fig. 3 c illustrative.

R among Fig. 3 c ₁Be that physics can be realized the target spectrum (δ).In the actual design, can realize,, adopt the THE DESIGN OF WINDOW FUNCTION thought that has in limit for length's unit impulse response (FIR) digital filter design method, r (δ) be carried out windowing cut toe, obtain r according to the causality of system for making dreamboat spectrum r (δ) physics ₁(δ).

When grating was even FBG, grating did not have chirp value and phase change, and coupling coefficient q is a real number.When grating was CFBG, coupling coefficient q was a plural number, its phase θ _q(z) characterize the chirped grating characteristic.

With reference to Fig. 4, illustrative requires the structural parameters (apodizing function and local chirp value) and the characteristic curve thereof of the chirped fiber grating of design according to the filter and dispersion compensation of reality.

Chirped fiber grating structural parameters figure shown in the figure designs according to following filter and dispersion compensation index:

Parameter name	Specific targets
		Centre wavelength	1550nm wave band ITU standard wavelength
Channel spacing	50GHz(0.4nm)
		Reflection bandwidth	@-30dB：0.5nm
@-1dB：0.3nm
	Reflectivity		99.5％
Dispersion compensation		1360ps/nm

The specific design process is: at first according to the target index, select this function representation dreamboat spectrum of superelevation of following form for use:

$r\left(\mathrm{\δ}\right)=\sqrt{0.995}\exp [-{\left(\frac{\mathrm{\δ}}{814}\right)}^6]\exp [-\frac{i{\mathrm{\β}}^{\′\′}L}{2}{\left(\frac{\mathrm{C\δ}}{n}\right)}^2]$

Wherein " be the second derivative of transmission β to frequency, L is the dispersion compensation distance to β, and C is the light velocity (3 * 10 ⁸M/s), n is an effective refractive index.Get β "=-21.7ps ²/ km (corresponding abbe number D=17ps/nmkm), L=80km establishes n=1.5, central wavelength lambda _b=1550nm, wavelength tuning range are 4nm, and grating length 10cm chooses Hanning window (Hanning) as window function.On the basis of above-mentioned parameter, design chirped fiber grating according to the described method of Fig. 3.

As shown in Figure 4, the apodizing function of grating does not have concrete analytical expression, is the function curve that obtains by numerical simulation; The chirped grating form is non-linear.From figure characteristic curve as can be known, designed chirped fiber grating meets the requirement of filter and dispersion compensation index fully.

With reference to Fig. 5, illustrate technical scheme of the present invention.Among the figure, light is from a port input of multiport optical directional coupler spare, enter chirped fiber grating according to optical transmission direction (this figure is for counterclockwise) through individual design, through optical grating reflection and dispersion compensation signal specific light reenter multiport optical directional coupler spare, at last from the output of the output port of coupled apparatus.

With reference to Fig. 6, illustrate non-limiting example one of the present invention.Multiport light direction coupled mode device is 3 decibels of photo-couplers in this example, is equipped with two identical chirped fiber gratings on two interference arms of Mach-Zehnder interferometer.Concrete structure as shown in the figure.The transmission signals λ of a plurality of wavelength ₁, λ ₂... λ _nFrom a port incident of 3 decibels of photo-couplers, the centre wavelength of establishing chirped fiber grating is λ ₂, can obtain the signal λ of dispersion compensation from port 2 ₂

With reference to Fig. 7, illustrate non-limiting example two of the present invention.Multiport light direction coupled mode device is 3 port photocirculators in this example, utilizes the chirped fiber grating of a plurality of cascades, need not to adopt independent dispersion compensation device again, and just demultiplexing goes out a plurality of distortionless flashlights simultaneously.As shown in the figure, multiplexed signals is λ ₁, λ ₂... λ _n, the centre wavelength of establishing the chirped fiber grating of four cascades is respectively λ ₁, λ ₂, λ ₃, λ ₄, four chirped fiber gratings all are to require to design according to concrete filter and dispersion compensation.A plurality of wavelength X of in same optical fiber, transmitting ₁, λ ₂... λ _nEnter optical circulator H port 3-1, flashlight λ ₁, λ ₂, λ ₃, λ ₄Successively from chirped fiber grating C ₁, C ₂, C ₃, C ₄After the reflection, download through optical circulator H port 3-3 again, realize 4 distortionless demultiplexings of signal simultaneously.As seen from the figure, adopt and thisly can realize simultaneously that the device of optically filtering and chromatic dispersion compensating function carries out the demultiplexing of a plurality of signals, have compact conformation, insert advantages such as loss is little.

With reference to Fig. 8, illustrate non-limiting example three of the present invention.By the device that can realize optically filtering and dispersion compensation simultaneously constitute a kind of optical add/drop multiplexer (Optical Add/Drop Multiplexer, OADM), realize individual signals upper and lower year.As shown in the figure, 3 port photocirculator H ₁As multiport light direction coupled mode device, (establish centre wavelength is λ to chirped fiber grating C ₂) and H ₁Port 3-2 links to each other; Recovery signal λ ₁, λ ₂... λ _nEnter circulator H ₁, λ ₂Behind optical grating reflection and dispersion compensation from H ₁Port 3-3 download, its commplementary wave length does not have added losses ground and passes through fiber grating, and uploads signal λ ₂After Light Coupled Device is combined into new multiplexed signals, export, realized the add drop multiplex of light.The advantage outstanding behaviours of this optical add/drop multiplexer has realized signal download and dispersion compensation simultaneously under the prerequisite that does not increase the device architecture complicacy.

Chirped fiber grating in the foregoing description all is that the filter and dispersion compensation according to practical application requires to carry out individual design, can make according to the method for well known to a person skilled in the art, therefore is not described further.

The selection of the embodiment of the invention and description are in order to explain practical application of the present invention better, so that those skilled in the art optimally use the present invention.

Above-mentioned description to the embodiment of the invention only is used for example and explanation, is not to limit the present invention in the described form.According to explanation of the present invention, can be under the condition that does not break away from the principle and scope of the present invention that appended claims limits, embodiment is made amendment and changes, obtain the embodiment of other form.

Claims (5)

1, a kind of device that can realize optically filtering and chromatic dispersion compensating function simultaneously, comprise light input end, light output end, at light input end, the device of filter and dispersion compensation is simultaneously arranged between the light output end, the device of filter and dispersion compensation is that multiport light direction coupled mode device and chirped fiber grating connect and compose simultaneously, it is characterized in that: multiport light direction coupled mode device has a plurality of ports, an one input end is as the light input end of entire device, output terminal is as the light output end of entire device, a port connects chirped fiber grating, wherein chirped fiber grating is to design according to concrete filtering index and dispersion compensation index, the concrete manifestation form of the apodizing function of grating and chirp value is determined by the target index, by designing different chirped fiber grating structures to satisfy different filter and dispersion compensation requirements.

2, the device that can realize optically filtering and chromatic dispersion compensating function simultaneously as claimed in claim 1, it is characterized in that: the device of realizing optically filtering and chromatic dispersion compensating function simultaneously is used for wavelength multiplex signals.

3, the device that can realize optically filtering and chromatic dispersion compensating function simultaneously as claimed in claim 1, it is characterized in that: multiport light direction coupled mode device is 3 decibels of photo-couplers, on two interference arms of Mach-Zehnder interferometer, be equipped with two identical chirped fiber gratings, the transmission signals of a plurality of wavelength obtains the signal identical with centre wavelength chirped fiber grating dispersion compensation from a port incident of 3 decibels of photo-couplers from port 2.

4, the device that can realize optically filtering and chromatic dispersion compensating function simultaneously as claimed in claim 1, it is characterized in that: multiport light direction coupled mode device is 3 port photocirculators, utilize the chirped fiber grating of a plurality of cascades, need not to adopt independent dispersion compensation device, just demultiplexing goes out a plurality of distortionless flashlights simultaneously again.

5, the device that can realize optically filtering and chromatic dispersion compensating function simultaneously as claimed in claim 1 or 2 is characterized in that: constitute a kind of optical add/drop multiplexer by the device that can realize optically filtering and dispersion compensation simultaneously, realize individual signals upper and lower year.

Images