CN1981468A - Method and apparatus for spectrum deconvolution and reshaping - Google Patents

Abstract

A method and apparatus for filter spectrum deconvolution and reshaping include providing a filter output of a spectrum signal and determining the intensity and wavelength of the spectrum signal at each spectral peak. The filter output is characterized as an integral of convolution of a spectrum signal function and a filter function. Transformation are then performed on the filter output to deconvolve and remove the undesirable filter function and add a desirable filter function to reshape the output filter spectrum.

Description

Be used for spectrum deconvolution and the method and the device that reshape

Technical field

The present invention is substantially about spectrum analysis, and in detail, about spectrum deconvolution (deconvolution) with reshape, this spectrum stems from for example optical diffraction grating, filtering devices such as tunable optical filter.

Background technology

Optical-fibre communications field comprises as fiber optic cables technology and fiber optic network technology.Fiber optic network has carried a large amount of daily life information, as call-information, data communication (as facsimile message), calculator to the transfer of data of calculator, cable TV, the Internet or the like.This type of information signal is in city and intercity each local transmission.Because the quick increase of communication transmission quantity, than the old-fashioned metallic cable than low capacity, the increase of fiber optic cables capacity becomes more and more important.

Typical fiber optic cables are made up of a branch of other optical fiber.Article one, single optical fiber can carry the thousands of data and the communication signal of single optical wavelength.Same optical fiber also can carry the complex light wavelength, so it can carry many composite optical signals simultaneously.The speed of each independent wavelength transmission data can surpass 10Gbit/s (10,000,000,000 bps).

In order to keep the communication of this kind optical-fiber network, need carry out multiple sensing analysis to each optical wavelength signal that on optical fiber, transmits, as the light signal of measuring light energy, wavelength and light signal to noise ratio.The instrument of finishing this alanysis be referred to as spectroanalysis instrument (optical spectrumanalyzer, OSA).Spectroanalysis instrument (OSA) is finished spectrum analysis (being also referred to as OSA), and promptly aforementioned measuring light energy is as the function of wavelength.

Typical spectroanalysis instrument (OSA) makes the light signal that will analyze by adjustable optical filter." adjustable " is meant and can adjusts filter to resolve or to extract the independent element (wavelength) of light signal.

The filter of three kinds of fundamental types is widely used in spectroanalysis instrument: diffraction grating, Fabry-Perot (FP) filter and Michelson interferometer.The adjustable FP filter (TFPF) that is used for OSA has many advantages, comprises mainly that design is simple relatively, size is little, speed is fast, easy to control and the light signal (that is to say that the frequency of signal or wavelength are very approaching) among a small circle had very strong resolving ability.

Yet, compare with the diffraction grating that is all 3-dB bandwidth (it is big little to be defined as under the peak wavelength value between 3-dB left side spectrum and the right spectral position or frequency value difference), the transmission curve of adjustable FP filter (TFPF) has relative " wide shirt rim (broad skirt) ".Wide shirt rim is meant that at the spectral position that has exceeded 3-dB bandwidth (BW) for example TFPF has slow relatively rejection rate (rejection rate) decay (decay) to the light signal of frequency or the contiguous signal of interest of wavelength.(wavelength division multiplexing, WDM) (optical-signal-to-noise-ratio can be considered the shortcoming very important to TFPF to the light signal of system signal in the time of OSNR) to noise ratio when being used for measuring wavelength division multiplexing in this wide shirt rim.It can make contiguous wavelength signals leaked and artificial lifting the bottom line of noise.This relative wide shirt rim allows crosstalk (the cross talk) of contiguous wavelength division multiplex (MUX), limited thus for OSNR measure the FP spectroanalysis instrument dynamic range (dynamic range, DR).

On the contrary, the transmission curve that is all the diffraction grating of 3-dB bandwidth has narrower shirt rim (steeper skirt), but its resolving ability to interior among a small circle light signal is strong not as TFPF.In theory, each optical filter all can allow from crosstalking that contiguous WDM channel comes, but because the narrow shirt rim of diffraction grating is then compared with the FP filter that is all the 3-dB bandwidth, it has littler crosstalking.

Therefore, increase substantially based on the FP spectroanalysis instrument measuring light signal of filter method and device and quite be necessary the dynamic range of noise ratio.Along with saving cost and the continuous growth of raising the efficiency demand, address the above problem and also become more and more important.

Seeking the solution of the problems referred to above for a long time, but prior art fails all to solve, it also be that the technical staff institute of this area is perplexed for a long time always.

Summary of the invention

The invention provides and be used for filter spectrum deconvolution (deconvolution) and the method and the device that reshape.The filter output of spectral signal is provided and judges light energy intensity at each this spectral signal of predetermined wavelength.The feature of this filter output expression input signal function and filter function convolution (convolution of integral).Then deconvolution two functional transformations being carried out in this filter output reshapes output filter spectrum.(convolution of integral with integralof convolution, all abbreviates convolution as in this article.)

Except the above, some embodiment of the present invention also comprises other advantage.The technical staff of this area is after having read following detailed description in conjunction with the accompanying drawings, and these advantages can become apparent.

Description of drawings

Fig. 1 is the calcspar according to spectroanalysis instrument of the present invention;

Fig. 2 is the schematic diagram of adjustable Fabry-Perot interferometer;

Fig. 3 is a polar plot, light beam in the adjustable Fabry-Perot interferometer of displayed map 2 and the electric field of following;

Fig. 4 is the distribution map of Lorentzian filter transmission curve;

Fig. 5 is the distribution map of Gaussian filter transmission curve;

Fig. 6 is Lorentzian filter curve and the Gaussian filter curve comparison diagram of Fig. 4 and Fig. 5;

Fig. 7 comprises three dense wave division multipurpose (DWDM) channels with vicinity of balanced energy for the spectrogram before the conversion, can be measured by the Fabry-Perot spectroanalysis instrument;

Fig. 8 is a spectrogram, the spectrum of displayed map 7 through quick Fourier transformation deconvolution of the present invention with reshape processing after spectrum;

Fig. 9 is being untreated of Fig. 7 and Fig. 8 and handles back curve comparison diagram;

Figure 10 comprises three DWDM channels with vicinity of unbalanced intensity for the spectrogram before the conversion, can be measured by the Fabry-Perot spectroanalysis instrument;

Figure 11 is a spectrogram, the spectrum that shows Figure 10 through quick Fourier transformation deconvolution of the present invention with reshape processing after spectrum;

Figure 12 is being untreated of Figure 10 and Figure 11 and handles back curve comparison diagram;

Figure 13 is the spectrogram of original not conversion, and it comprises that to surpass 40 intensive with the isolated division multiplex (MUX) of 50GHz, can be measured by the Fabry-Perot spectroanalysis instrument;

Figure 14 is a spectrogram, the spectrum that shows Figure 13 through quick Fourier transformation deconvolution of the present invention with reshape processing after spectrum;

Figure 15 is being untreated of Figure 13 and Figure 14 and handles back curve comparison diagram;

Figure 16 is a flow chart, shows according to the Fabry-Perot of being used for filter spectrum deconvolution of the present invention and the method that reshapes.

The primary clustering symbol description

100 spectroanalysis instruments (OSA), 102 light shifters

104,106,116,124 input ports

108,110,114,122 optical fiber

112,120 delivery outlets, 118 adjustable FP filters (TFPF)

126 wave detectors, 128,132,136 transmission lines

130 analyzers, 134 displays

138 registers, 140 calculators

206,208 speculums, 210 cavitys

212,214 light, 216,218 functions

400 Lorentzian filter transmission curve distribution maps

402 Lorentzian filter curve

404 shirt rims

500 Gaussian filter transmission curve distribution maps

502 Gaussian filter curve

600 Lorentzian filter curve 402 and Gaussian filter curve 502 comparison diagrams

700,800,1000,1100,1300,1400 spectrum

702,802,1002,1102,1302,1402 curves

The comparison diagram of 900 curves 702 and curve 802

1104 weak energy channels

1200 be untreated curves 1002 and handle the comparison diagram of back curve 1102

1500 be untreated curves 1302 and handle the comparison diagram of back curve 1402

1600 methods

1602,1604,1606,1608,1610 square steps

Embodiment

In order to understand the present invention fully, a plurality of certain embodiments in following explanation, have been listed.Yet, obviously do not use these specific embodiments can realize the present invention yet.For avoiding obscuring with the present invention, some available circuits and system configuration do not disclose in detail.Simultaneously, for clearly demonstrating the present invention, the accompanying drawing of embodiment is part diagram rather than by the proportional reduction of actual conditions.In addition, in the diagram identical digitized representation the identical or assembly that function is identical.

Spectroanalysis instrument (OSA) is used for spectrum analysis (being also referred to as OSA in this article), normally makes light signal pass through tunable optical filter.Light signal claims " spectral signal " again, because it has comprised the spectrum of many unlike signal wavelength.The independent wavelength components of light signal is resolved or extracted to tunable optical filter then.Minimum wavelength between two spectral components that can reliably be parsed in the spectral signal is called the spectral resolution (spectral resolution) of spectroanalysis instrument at interval.For reaching high spectral resolution, filter should have the enough narrow bandwidth at the 3-dB place.

For multiple measurement, its amplitude of various spectral components that measure is also unequal.The measurement of the side mode suppression (side-mode suppression) that example is the distributed Feedback laser.(" side mode suppression " is meant the inhibition of the unwanted longitudinal propagation pattern of either side of desired vertical pattern.The inhibition degree of undesired mode is called " side mode suppression rate ".) for this kind metering system, as long as consider the 3-dB filter bandwidht, filter shape is not very important yet, filter shape has been determined light rejection ratio (the optical rejection ratio of a distance, ORR), for example, departing from main transmission frequency ± 25GHz place.

Fabry-Perot (FP) filter is wherein a kind of filter commonly used in the spectroanalysis instrument.This filter comprises cavity, each end of this cavity by two parallel, that part is silver-plated, have high reflectance and the speculum that can relatively move is the border.The transmission spectrum of FP cavity is a function of wavelength, has shown the crest corresponding to the big transmission of the resonance frequency of cavity.

Interference more than between two reflectings surface between the reverberation can produce the different transfer function of FP cavity.If transmitting beam is a same-phase, then can produce constructive interference, it is to there being the high-transmission crest of FP cavity.If transmitting beam is an out of phase, then can produce destructive interference, it is to there being the transmission minimum value.Whether a plurality of folded light beam is same-phase or out of phase, depends on light wavelength, the light refractive index by medium between the angle of cavity, distance (length of cavity just), reflecting surface between the mirror surface.

Because can mobile mirror change the distance between their reflecting surface, so the FP cavity is an adjustable filter.This kind is adjustable FP filter (TFPF) but the bandwidth furnishing has very narrow 3-dB, but it also can have the 20-dB bandwidth of relative broad, i.e. " wide shirt rim ".(referring to the shirt rim 404 of Lorentzian filter curve 402 among Fig. 4.)

One of them major advantage of FP filter is that it has very narrow 3-dB bandwidth.Therefore the spectroanalysis instrument based on the FP filter has very high spectral resolution, and for example, it can measure laser chirp (chirp) (that is to say the frequency scintillation of the laser light of impulse duration (wavering)).Yet because it has wide shirt rim, the light rejection ratio (ORR) of adjustable FP filter is restricted.For instance, fineness (finesse) value up to 7200 and the 180nm Free Spectral Range (Free Sprctrum Range, TFPF FSR) is less than 25.0dB in the light rejection ratio of ± 25GHz.(" fineness " is the ratio of the live width of the spaced apart interferometer fringe line of spectrum line interval series of rules.)

The wide shirt rim of this kind is unaccommodated to some application.For example, be spaced apart the dense wave division multipurpose of 50GHz (dense wavelength division multiplexing, DWDM) in the system, ± the 25GHz place requires the light rejection ratio up to 35.0dB.Otherwise the wide shirt rim transmission curve of TFPF can be introduced crosstalking or disturbing of contiguous DWDM channel, and it has limited light rejection ratio and the spectroanalysis instrument measuring light signal dynamic range (DR) to noise ratio (OSNR).

As described herein, the mathematical reverse convolution can solve and overcome this significant drawbacks of FP filter with the method that reshapes, and can improve the dynamic range (DR) of measuring OSNR based on the spectroanalysis instrument (OSA) of FP filter widely.In one of the present invention aspect, this filter output at first is characterized as the convolution of two mathematical functions.First function is the input optical signal function before the filter.Second function is a filter function, is the transfer function of adjustable FP filter in this situation.Light signal and tunable filter interaction produce the output from the FP filter, and this output is the mathematics convolution of two mathematical functions.

The present invention proposes and uses the suitable FP filter that is converted in to export then, remove the FP filter function that has from the wide shirt rim that output is sent here effectively, add another filter function with narrow shirt rim (such as Gaussian function) that needs again, export light signal spectrum thus and can reshape and improve the dynamic range of measuring-signal noise ratio.The feasible like this spectroanalysis instrument based on the FP filter not only has high spectral resolution, and also has high light rejection ratio.This response characteristic is in demand, is not only applicable to the DWDM spectrum monitoring, also is applicable to other many application.

With reference now to Fig. 1,, it has shown spectroanalysis instrument of the present invention (OSA) 100 with calcspar.This OSA 100 comprises light shifter (optical switch) 102, has input port 104 and 106.Input port 104 is positioned in the branch of this light shifter 102, and this input port 104 is connected with the monomode fiber 108 that carries tested light signal.Optical fiber 108 and input port 104 actings in conjunction are to be used for the input of the light signal of OSA 100.

In a similar manner, input port 106 is positioned at another branch of this light shifter 102, and is connected with the monomode fiber 110 that carries the reference wavelength light signal.Optical fiber 110 and input port 106 actings in conjunction are to be used for the input of the reference wavelength signal of OSA 100.

The delivery outlet 112 of light shifter 102 is connected to the input port 116 of adjustable FP filter (TFPF) 118 by optical fiber 114.Then, the delivery outlet 120 of TFPF 118 is connected to the input port 124 of wave detector 126 by optical fiber 122.This wave detector 126 is a receiver, receives by TFPF 118 selected light signals, and this wave detector is connected to analyzer 130 by transmission line 128.Transmission line 132 connects analyzer 130 and display 134 (as video display or graphic alphanumeric display).Transmission line 136 connects analyzer 130 and register 138.When needs, the running of spectroanalysis instrument (OSA) 100 can be by calculator 140 coordinated manipulations, and this calculator is connected with light shifter 102, adjustable FP filter 118, wave detector 126, analyzer 130, display 134 and register 138.The suitable circuit of the common in a different manner composition of wave detector 126, analyzer 130 and calculator 140 is to implement every function of the present invention described herein.

With reference now to Fig. 2,, shown the schematic diagram of typical adjustable FP interferometer (TFPI), be applied to the present invention and promptly be the adjustable FP filter (TFPF) 118 in the spectroanalysis instrument (OSA) 100 (Fig. 1).This TFPF 118 comprises the speculum 206 and 208 of partial reflection.The crack separates between speculum 206 and 208 quilts such as the cavity 210, has wherein filled up particular electrical medium such as air, glass etc.TFPF 118 is injected and passed to light 212, is filter light 214 again after TFPF 118 penetrates.

As previously mentioned, the convolution of this tunable filter is exported the convolution of its characteristic light input signal function and tunable filter function.In detail, the light 212 with the analyzed spectral distribution of desire is used light input signal function 216 performance characteristics then.Act on the effect of the TFPF 118 of light input signal function 216, by filter function 218 performance characteristics of TFPF 118.In the tuning process of TFPF, the synthetic filter light 214 usefulness light input signal functions 216 and convolution 220 performance characteristics of tunable filter function 218.

With reference to figure 3, it is a polar plot 300, is shown in incident, reflection, and transmitting beam and their interaction of following electric field and the analysis of (Fig. 2) among the TFPF 118.The incident electric field R of light 212 ₀At speculum 206 with reflection factor r ₀(at cavity 210 " external reflectance ") partial reflection is in addition with transmission factor t _iThe transmission of (in cavity 210 " interior transmission ") part.When transmitting electric field with the transmission factor t in the cavity 210 _iWhen passing cavity 210 by speculum 208, it can be with factor t _oPostpone and multiplication in speculum 208 backs.When following equation is set up, from the reverberation R of speculum 206 ₁, R ₂, R ₃Deng can being subjected to maximum destructive interference, and from the transmission light T of speculum 208 ₁, T, T ₃Deng can being subjected to maximum constructive enhancing:

$\frac{2\mathrm{\πnL}}{\mathrm{\λ}}=\mathrm{m\π},---\left(1\right)$

Wherein m is any positive integer, and L is the length of resonant cavity (as cavity 210), and n is the refractive index of medium in the resonant cavity, and λ is the wavelength of light signal, and therefore transmits light wave.Following equation is determined the resonance frequency f of FP cavity _m:

$f_m=\frac{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="A20058002278000191.png"\; state="\{\{state\}\}">c</figure-callout>}}{2\mathrm{Ln}}m---\left(2\right)$

The FSR of FPI is defined as mode spacing (mode spacing).

F represents with frequency of light wave, and FSR is:

$\mathrm{FSR}(f)=\frac{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="A20058002278000191.png"\; state="\{\{state\}\}">c</figure-callout>}}{2\mathrm{Ln}}---\left(3\right)$

λ represents with optical wavelength, and FSR is:

$\mathrm{FSR}\left(\mathrm{\&lambda;}\right)=\frac{{\mathrm{\&lambda;}}^2}{2\mathrm{Ln}}---\left(4\right)$

The transmission bandwidth of FP filter is defined as full duration (FWHM) or the 3-dB in half maximum.It is defined by following equation:

$B=\frac{1-\mathrm{<figure-callout\; id="2"\; label="r\; r\; c"\; filenames="A20058002278000191.png"\; state="\{\{state\}\}">r</figure-callout>}}{\sqrt{r}}\frac{c}{}\frac{}{2\mathrm{\&pi;nL}}---\left(5\right)$

Correlation bandwidth and mode spacing FSR produce fineness F:

$F=\frac{\mathrm{FSR}}{B}=\frac{\mathrm{\&pi;}\sqrt{r}}{1-r}---\left(6\right)$

The transmission curve of FP cavity can be illustrated by air function (Airy Function):

$A\left(\mathrm{\&lambda;}\right)=\frac{I_0}{1+{\left(\frac{2F}{\mathrm{\&pi;}}\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A20058002278000191.png"\; state="\{\{state\}\}">sin</figure-callout>}\frac{2\mathrm{\&pi;nL}}{\mathrm{\&lambda;}}\right)}^2},---\left(7\right)$

I wherein ₀Be the peak transmission luminous intensity.

Above-mentioned air function can be similar to following Lorentzian distribution function:

$L\left(f\right)=\frac{I_0}{1+4{\left(\frac{f-f_0}{B}\right)}^2},$

F wherein ₀Be the peak transmission frequency.

The 3-dB bandwidth that Lorentzian distributes by $B=\frac{1-\mathrm{<figure-callout\; id="2"\; label="r\; r\; c"\; filenames="A20058002278000191.png"\; state="\{\{state\}\}">r</figure-callout>}}{\sqrt{r}}\frac{c}{}\frac{}{2\mathrm{\&pi;nL}}$ Expression, wherein r is the reflectivity of filter mirror, and c is a light propagation velocity in a vacuum, and L is the length of filter cavity (as cavity 210).This type of filter with Lorentzian transmission curve is called " Lorentzian filter ".

In contrast, the transmission curve of traditional diffraction grating is represented with the Gaussian distribution function:

$G\left(f\right)=I_0{e}^{\frac{{(1-I_0)}^2}{{I0}^2}---\left(9\right)}$

Wherein σ defines the BW that Gaussian distributes.This type of filter with Gaussian transmission curve is called " Gaussian filter ".

Adjustable FP filter (TFPF) and diffraction grating may be used to make up spectroanalysis instrument (OSA).Yet as discussed previously, for the applications use TFP OSA of DWDM for example, one of its subject matter is, compares with the transmission curve of the diffraction grating that is all the 3.0-dB bandwidth, and the transmission curve of this filter has wide relatively shirt rim.The broad shirt rim of this TFPF means filter very easily from very narrow interval, finds signal near contiguous channel, and has therefore covered the signal that really will pay close attention to.

With reference to figure 4, wherein show the example of Lorentzian filter transmission curve distribution map 400, by 402 expressions of Lorentzian filter curve.As shown in FIG., this filter has 3-dB bandwidth (BW) and is about 6.6GHz.Leave main transmision peak, shown in shirt rim 404, the light rejection ratio (ORR) of this filter is about 23.0dB when ± 50GHz, and the ORR when ± 100GHz is 29.0dB.

With reference to figure 5, it is the example of Gaussian filter transmission curve distribution map 500, by 502 expressions of Gaussian filter curve.This filter has the 3-dB bandwidth and is about 33GHz.Leave main transmision peak, shown in shirt rim 504, the ORR of this filter is about 25.0dB (close with the Lorentzian filter) when ± 50GHz, and the ORR when ± 100GHz is greater than 70.0dB.

With reference to figure 6, it is the comparison diagram 600 of Lorentzian filter curve 402 and Gaussian filter curve 502.Though the 3-dB bandwidth of Lorentzian filter curve 402 only is 1/5 of a Gaussian filter curve 502, because the wide shirt rim 404 of Lorentzian filter curve, it has much lower ORR when leaving the filter transmision peak greater than ± 50GHz.Therefore Fig. 6 has illustrated based on the spectroanalysis instrument measuring light signal of FP filter the dynamic range (DR) of noise ratio (OSNR) than based on the much smaller reason of the spectroanalysis instrument of diffraction grating.

Explain that from mathematical terms arbitrary measure spectrum all is to constitute the filter function of OSA and the convolution of input optical signal.Therefore, if input optical signal is represented that by function R (f) output spectrum of using the Lorentzian filter measurement is by P _L(f) expression, and with the output spectrum of Gaussian filter measurement by P _G(f) expression, so following equation is set up:

$P_L\left(f\right)={\&Integral;}_{-\&infin;}^{\&infin;}R\left(f_0\right)L(f-f_0)\mathrm{<figure-callout\; id="0"\; label="d\; f"\; filenames="A20058002278000191.png,A20058002278000201.png"\; state="\{\{state\}\}">d</figure-callout>}{f}_{}{}_0,---\left(10\right)$

$P_G\left(f\right)={\&Integral;}_{-\&infin;}^{\&infin;}R\left(f_0\right)G(f-f_0)\mathrm{<figure-callout\; id="0"\; label="d\; f"\; filenames="A20058002278000191.png,A20058002278000201.png"\; state="\{\{state\}\}">d</figure-callout>}{f}_{}{}_0,---\left(11\right)$

L (f-f wherein ₀) and G (f-f ₀) represent with f respectively ₀Lorentzian distribution function and Gaussian distribution function for the center.

Fourier transformation law according to convolution:

F[P _L(f)]＝F[R(f)]·F[L(f)]， (12)

F[P _G(f)]＝F[R(f)]·F[G(f)]， (13)

F[P wherein _L(f), F[R (f)], F[L (f)], F[P _G(f)] and F[G (f)] represent P respectively _L(f), R (f), L (f), P _G(f) and the Fourier conversion of G (f).Derive following the present invention's deconvolution and the equation that reshapes method thus, specifically be expressed as follows:

$P_G\left(f\right)=F^{-1}[\frac{F\left[P_L\left(f\right)\right]}{F\left[L\left(f\right)\right]},F[G\left(f\right)\left]\right],---\left(14\right)$

In one of the present invention embodiment, use the spectroanalysis instrument (OSA) of TFPF, S, C and the L band wavelength scope of implementing dense wave division multipurpose (DWDM) are 1470nm to 1630nm.The Free Spectral Range of employed TFPF (FSR) is about 180nm, and fineness is about 7200, and the 3-dB bandwidth is about 25pm.The light rejection ratio (ORR) of this kind filter when leaving filter transmission crest 25.0GHz and 50.0GHz is respectively about 24.5dB and 30.0dB.This highest light signal of just representing this OSA energy measurement will be lower than 24.5dB to noise ratio (OSNR) at 50GHz isolation DWDM channel, will be lower than 30.0dB and isolate the DWDM channel for 100GHz.

With reference to figure 7, show spectrum 700, represent original, the untreated smooth data of coming from the DWDM channel of three vicinities by curve 702.This spectrum 700 also can be measured by the Fabry-Perot spectroanalysis instrument.

With reference to figure 8, show spectrum 800, by of quick Fourier transformation (FFT) deconvolution and the situation that reshapes the processing back of curve 802 expression spectrum 700 (Fig. 7) by the present invention.

With reference to figure 9, show the comparison diagram 900 of be untreated curve 702 and processing back curve 802.Deconvolution and reshape spectrum 800 (Fig. 8) and also shown to increase and surpass more than the 15.0dB in ± 25GHz light rejection ratio, this be since the FFT deconvolution with reshape the shirt rim that makes filter function and become steeper.OSNR measured value according to the spectrum 700 (Fig. 7) of untreatment data is about 20.0dB.Yet, through the present invention's FFT deconvolution with reshape conversion (handle and reshape) after similarly be about 40.0dB according to the OSNR measured value of spectrum 800.

With reference to Figure 10, show spectrum 1000, it shows original, the untreated smooth data and curves 1002 of the DWDM channel of three vicinities with unbalanced energy.The energy of intermediate channels is about-34.5dBm, and two channels are about 0.0dBm in addition.The unbalanced difference of energy is greater than 34.0dB.The spectrum 1000 of the data that is untreated is measured with FP OSA, only resolves weak energy channels, because about should weak energy channels being covered by under the shirt rim of two contiguous DWDM channels.

With reference to Figure 11, show spectrum 1100, its show spectrum 1000 (Figure 10) by the present invention quick Fourier transformation (FFT) deconvolution and reshape processing after curve 1102.This deconvolution with reshape spectrum 1100 and clearly resolved weak energy channels 1104.Energy is crosstalked by the FFT deconvolution and is reshaped almost completely and is removed, and it gives weak energy channels 1104 and contrasts more clearly.

With reference to Figure 12, show the comparison diagram 1200 of be untreated curve 1002 and processing back curve 1102.

With reference to Figure 13, show spectrum 1300, be with comprising that the original untreated curve of spectrum 1302 more than 40 isolated DWDM channels of 50GHz represents.This spectrum 1300 usefulness FP OSA measure.

With reference to Figure 14, show spectrum 1400, be to represent with the FFT deconvolution of spectrum 1300 (Figure 13) by the present invention and the curve 1402 that reshapes after the processing.

With reference to Figure 15, show the comparison diagram 1500 of be untreated curve 1302 and processing back curve 1402.This comparison diagram has illustrated that once more the present invention's FFT deconvolution and the method that reshapes are effectively.In detail, be untreated curve 1302 and the comparison diagram 1500 of handling back curve 1402 is shown in that the light rejection ratio (ORR) at place has increased above more than the 15dB in the middle of the adjacent channel.

Therefore, the filter transmission curve increases dynamic range (DR) by " being reshaped " according to the present invention's FFT deconvolution and method that reshapes and device based on the spectroanalysis instrument (OSA) of FP filter.Based on the embodiment that the present invention disclosed, those skilled in the art can know understanding, and the filter transmission curve can be reshaped by the mode of using hardware, software or both combinations.

For example, if use hardware mode that the filter transmission curve is reshaped, then need to use another to have the filter of the transmission curve of particular design.Additional filter and the stack of FP filter obtain the synthetic transmission curve of two filters, and it is similar to the Gaussian filter.This kind convergence mode can reach, but very difficult.

Therefore the present invention proposes the less software FFT deconvolution of a kind of difficulty and reshape method, i.e. " software filter ", its effect more is better than the hardware filtering device.Its gross effect is equivalent to this software filter and the stack of hardware FP filter is obtained suitable synthetic Gaussian transmission curve.

As preceding detailed description, realize by following steps according to the present invention's deconvolution and the method that reshapes the FP filter spectrum of light signal:

1. feature performance FP filter spectrum is the convolution of light input signal function and filter function.FP filter spectrum is carried out quick Fourier transformation (FFT).

2. foundation has the suitable Lorentzian function of optimum bandwidth and it is carried out FFT.

3. foundation has the suitable Gaussian function of optimum bandwidth and it is carried out FFT or only sets up suitable function, and it is equivalent to the FFT of Gaussian function.

4. with the result of step 1 result divided by step 2.

5. the result of step 4 be multiply by the result of step 3.

6. the result to step 5 carries out the FFT inverse transformation.

" optimum bandwidth " is meant that the bandwidth of filter can make deconvolution thereafter the most effective.

The ultimate analysis result is the spectrum that is similar to the output of Gaussian filter.Therefore, first filter function (as the FP filter function) is removed, and adds and to have optimum bandwidth second filter function (as Gaussian) of (for example when ± 25GHz, DR has increased 15.0dB at least), and the filter output spectrum is reshaped.

When spectrum was still represented by the Lorenzian filter, before the FFT deconvolution and reshaping, the position of spectrum peak and intensity at first were positioned and preserve.Use deconvolution then and reshape OSNR and the dynamic range of improving light signal.In this mode, the present invention utilizes the steep narrow 3-dB bandwidth of FP filter to find out the meticulous spectral composition of input optical signal, uses deconvolution then and reshape to handle to obtain measuring the more accurate OSNR result of OSNR and better dynamic range (DR).The spectrum peak that obtains through this process is preferable usually and be the Gaussian form, and it is better than the Lorentzian form.This method can be recycled and reused in the spectrum of spectral signal each required wavelength to determine the corresponding discrete signal power to each indivedual required wavelength.

With reference to Figure 16, show the flow chart of filter spectrum deconvolution of the present invention and the method 1600 that reshapes.This method 1600 comprises square 1602, and the output of spectral signal filter is provided; Square 1604 is determined the position and the intensity of each peak value of spectral signal; Square 1606, feature performance filter is output as the convolution of input optical signal function and filter function; Square 1608 is carried out the deconvolution conversion to the filter output of two functions; And square 1610, remove the FP filter function and add suitable Gaussian filter function.

Therefore the invention provides a kind of novelty, that improve and the unconspicuous spectroanalysis instrument (OSA) that forms based on FP filter structure, it uses deconvolution and reshapes to increase the light rejection ratio (ORR) and the dynamic range (DR) of measuring light signal to noise ratio (OSNR).In one embodiment, use novel and unconspicuous deconvolution to make up the OSA that the forms DR the when ± 25.0GHz based on the FP filter and increase 15.0dB at least with reshaping to make.Therefore deconvolution of the present invention has solved with the method for reshaping and has used the FP filter to be difficult to reach this subject matter of high DR in OSA.

Said, make up the spectroanalysis instrument that forms based on FP accurate spectrum resolution not only can be provided, can also be provided for DWDM and measure the very high dynamic range of OSNR, and other better application.Disclosed based on the present invention, obviously equally also be suitable for more OSA and use.As described here, according to recent needs and/or application, it is also conceivable that filter function (for example Butterworth filter) and other the deconvolution of using other and reshape.

Similarly, as described herein, those skilled in the art can know that the deconvolution of understanding the present invention and the method that reshapes and device also are applicable to other signal and spectral information.For example, it can be applicable to infrared ray, microwave, megahertz (terahertz) and other radiofrequency signal and signal extension.It also can for example be applied to medical science spectrum (as the blood of human body transmission spectrum).

Therefore, the present invention's FP filter spectrum deconvolution and the method that reshapes and device are to offer so far based on FP filter make up that the optical signal analyzer that forms increases dynamic range (DR) and make that FP filter transmission curve reshapes important and the solution that still unknown Buddhist monk does not utilize, its performance is good, and is functional strong.Its process and structure are understandable, economical, simple, general, accurate, sensitive and effective, and it cooperates known assembly to realize in making and using.

Though described the present invention in conjunction with certain preferred embodiment, the technical staff of this area can understand, and still can carry out according to the above description multiplely substituting, modification and conversion.Therefore, the present invention comprise that all that fall into claim substitute, modification and conversion.Shown in all said or accompanying drawings is illustrative and unrestricted the present invention.

Claims (10)

1. one kind is used for filter spectrum (700) deconvolution and the method (1600) that reshapes, and comprises step:

The filter output (214) of (1602) spectral signal (212) is provided;

Determine the intensity and the wavelength of (1604) this spectral signal (212) at each spectrum crest;

This filter output (214) of feature performance (1606) is the convolution of input spectrum signal function (216) and first filter function (218);

Two functions (216,218) to this filter output (214) are carried out (1608) deconvolution conversion; And

Removing (1610) this first filter function (218) and adding second filter function (502) with predetermined optimum bandwidth reshapes filter output (214) spectrum (700).

2. the method for claim 1 (1600) wherein provides the filter output (214) of spectral signal (212) further to comprise with adjustable Fabry-Perot filter (118) measure spectrum signal (212).

3. the method for claim 1 (1600) wherein provides the filter output (214) of spectral signal (212) further to comprise the filter output (214) that spectral signal (212) is provided.

4. the method for claim 1 (1600) wherein provides the filter of spectral signal (212) to export the filter output (214) that (214) further comprise the spectral signal (700) that dense wave division multipurpose DWDM is provided.

5. the method for claim 1 (1600), further comprise variously in the spectrum (700) to spectral signal (212) needing that wavelength repeats that this provides (1602), determines (1604), feature performance (1606), carrying out conversion (1608) and remove operation (1610), with definite to respectively needing the discrete signal power of individual wavelengths correspondence.

6. one kind is used for filter spectrum (700) deconvolution and the device (100) that reshapes, and comprising:

Filter (118) is used to provide the filter output (214) of spectral signal (212);

Wave detector (126) is used for determining at each spectrum crest the intensity and the wavelength of this spectral signal (212);

Be used for feature and show the circuit (140) of this filter output (214) for the convolution of input spectrum signal function (216) and first filter function (218);

Be used for two functions (216,218) of this filter output (214) are carried out the circuit (140) of deconvolution conversion; And

Be used to remove this first filter function (218) and add the circuit (140) that second filter function (502) with predetermined optimum bandwidth reshapes filter output (214) spectrum (700).

7. device as claimed in claim 6 (100), wherein this filter (118) further comprises adjustable Fabry-Perot filter (118).

8. device as claimed in claim 6 (100), wherein this filter (118) further comprises the filter that is used to provide spectral signal (212) filter output (214).

9. device as claimed in claim 6 (100), wherein this filter (118) further comprises the filter of the filter output (214) that is used to provide dense wave division multipurpose DWDM spectral signal (700).

10. device as claimed in claim 6 (100), further comprise be used for to the spectrum (700) of spectral signal (212) variously need that wavelength repeats that this provides, determines, feature performance, the circuit (140) carrying out conversion and remove operation, to determine to respectively needing the discrete signal power of individual wavelengths correspondence.

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