CN104111570A - Method and device for generating transmittable high-power pulse string - Google Patents

Abstract

The invention belongs to the field of nonlinear optical research, and in particular relates to a method and a device for generating a transmittable high-power pulse string. The technical problem that the current high-power pulse string with continuous wave background cannot transmit stably is solved. The device for generating the transmittable high-power pulse string comprises the following steps: a, generating a beam of high-power pulse string with continuous wave background; b, separating the beam of high-power pulse string with continuous wave background into at least two beams, wherein the first beam is input into an optical spectrum analyzer, and the second beam is input into an optical adjustable band-strop filter; c, according to the wave length of pump wave, represented by the center frequency of the high-power pulse string with continuous wave background, analyzed by the optical spectrum analyzer, filtering the back ground waves of the center frequency part of the high-power pulse string with continuous wave background to obtain the transmittable high-power pulse string with zero background. The method and the device for generating the transmittable high-power pulse string are simple, convenient and efficient, and have important application value in high-power pulse transmission in optical fiber communication.

Description

A kind of generation can be transmitted the method and apparatus of high power pulse string

Technical field

The invention belongs to the nonlinear optics research field in optical communication, be specially a kind of generation and can transmit the method and apparatus of high power pulse string.

Background technology

Along with infotech transmission speed is upgraded day by day, in the last few years, Fibre Optical Communication Technology was paid attention to widely at present and was applied.Wherein increase the capacity of communication system, improve traffic rate, increasing pulse power is important research direction.Current improve communication network capacity, mainly utilize the technological means such as wavelength-division multiplex and time division multiplex to carry out, and in single channel, improve information capacity, need to produce the high-quality ultrashort pulse of high-repetition-rate.But average power is limited and the poor efficiency of energy, limit the application of these ultrashort pulse strings.Monopulse peak power is subject to again the impact of the factor such as nonlinear effect, light loss.Therefore the pulse train that produces high power, high-repetition-rate is an important goal in research.

Nowadays, the conventional ultrashort pulse sequence that produces generally realizes by active or passive mode-locking method.By being carried out to shaping, beat frequency coherent source compresses to produce the train of impulses of high-repetition-rate, owing to being subject to the long restriction in chamber, repetition frequency generally at tens megahertzes to hundreds of megahertz, be difficult to improve again, and the variation of environment can cause the destruction of mode-lock status, laser instrument can not effectively be worked.In addition, also include the devices such as electrooptic modulator to being the restriction that uses speed.Compared with the photoelectric method traditional with other, based on the nonlinear effect in optical fiber of pulse, can make very fast-response of pulse, be collapsed into high-power train of impulses.In this case, can be by regulating the initial modulation cycle to change train of impulses repetition frequency, the pulse repetition rate of acquisition is up to even tens Terahertzs of tens GHzs.Therefore, utilizing Kerr nonlinearity in optical fiber to replace traditional troublesome operation mode-locked laser to produce train of impulses is a practicality and effective ways to one's profit.

In fibre system because dispersion and nonlinear interaction can produce modulational instability, this modulational instability can allow the continuous wave with disturbance through strong compression and the growth of peak power, and this quasi c. w. division produces ultrashort pulse string the most at last.In the world, modulational instability produces ultrashort light pulse early research.As far back as 1992, Agrawal adopted Erbium-Doped Fiber Amplifier (EDFA) to utilize continuous light source to produce the femtosecond pulse string output of high repetition frequency.(IEEE?Photon.Technol.Lett.,1992,4,562)。Wherein, the conventional method of initial continuous wave dither modulation is to carry out double frequency beat frequency light wave by two continuous wave lasers to be coupled to produce.In addition can also produce through phase-modulator and intensity modulator by a continuous wave laser.The people such as B.Kibler in 2010 utilize two carrier-class outside cavity gas lasers (ECL-OSICS model1560-PM) to input as signal, in highly nonlinear optical fiber (OFS special fiber), realize the strange ripple of optics of strong Local Structure, form the high power pulse (Nat.Phys.2010 with background wave at peak value place, 6,790); The people such as K.Hammani in 2011 obtain the strange ripple of optics that comprises high power pulse in the telecommunication optical fiber (SFM-28) of standard commercial; Modulational instability frequency spectrum dynamics (Opt.Lett.2011,36,112 are studied; Opt.Lett.2011,36,2140).Here optical fiber not only can transmission light pulse, and it is also as the instrument of shaped pulse.By a Soliton Compression mechanism of knowing, pulse just can be by temporary transient compression.Because pulse energy is in this course constant, after compression, peak power also can increase accordingly.Such weak pulse punching is embedded in one and constantly obtains energy for it provides in the continuous wave background of energy, and the growth of intensity index, has finally obtained a high power pulse string being embedded on continuous wave background pedestal at peak value place.But these high power pulse strings of having powerful connections are to transmit in optical fiber, the decay that its intensity can be very fast.Must eliminate background wave pedestal and just can carry out stable transfer.About eliminating background wave method, there is researcher to propose to utilize polarization technology to eliminate continuous background ripple (Opt.Lett.1982,7,512) before; Also someone proposes to utilize Ramam effect to eliminate background wave (Opt.Lett.1990,15,1365).Nearest researching and proposing by phase-interferometer utilizes the method for phase coherence to realize the elimination (Sci.Rep., 2012,2,463.) to background wave.In these technical methods, the too much experimental provision of needs that cannot eliminate background completely, have having is realized, and does not verify the transport property of these elimination backgrounds pulses afterwards.Therefore need a kind of new, convenient, effective method to remove background wave, obtain can stable transfer high power pulse string.

Summary of the invention

The present invention solves to have at present the technical matters that the high power pulse string of continuous wave background can not stable transfer, provides a kind of generation can transmit the method and apparatus of high power pulse string.

The present invention realizes by the following technical solutions: a kind of generation can be transmitted the method for high power pulse string, comprises the following steps: (a) produce a branch of continuous wave background high power pulse string; (b) this continuous wave background high power pulse string is at least divided into two bundles, the first bundle inputs in an optical spectrum analysis instrument, and the second bundle inputs to an optics tunable band-stop filter; Described optics tunable band-stop filter is the adjustable filter with narrow-band band-elimination filtering function; (c) analyze the wavelength of the pumping wave of continuous wave background high power pulse string centre frequency representative according to optical spectrum analysis instrument, and by regulating optics tunable band-stop filter to determine the centre wavelength that needs filtration, the centre frequency part background wave of continuous wave background high power pulse string is filtered, obtain the high power pulse string that zero background can be transmitted.

The present invention utilizes exocoel continuous wave laser to produce the continuous wave inceptive impulse through ovennodulation by phase-modulator and intensity modulator, after utilizing Erbium-Doped Fiber Amplifier (EDFA) to amplify, be input to compression in single-mode fiber and form the high power pulse string with continuous wave background, then utilize optics tunable band-stop filter to filter out background wave, obtain the high power pulse string of zero background, this high power pulse string can be in optical fiber middle and long distance stable transfer.Adopt optics tunable band-stop filter to filter out the principle of high power pulse of zero background as follows: the transmission of light pulse in the single-mode fiber without gain (or loss) is to describe by non-linear Schrodinger equation, as follows:

$i\frac{\∂\mathrm{\ψ}}{\∂\mathrm{\ξ}}-\frac{{\mathrm{\β}}_2}{2}\frac{{\∂}^2\mathrm{\ψ}}{{\∂\mathrm{\τ}}^2}+\mathrm{\γ}{\left|\mathrm{\ψ}\right|}^2\mathrm{\ψ}=0---\left(1\right)$

Wherein, ψ (ξ, τ) is the slow change envelope amplitude of light pulse, and ξ and τ are that group velocity moves transmission range and the time under reference frame.γ is nonlinear factor, β ₂it is GVD (Group Velocity Dispersion) coefficient.This equation has that the limited background orphan of individual special shape--Akhmediev breathes solution, and form is as follows:

$\mathrm{\ψ}(a,\mathrm{\ξ},\mathrm{\τ})=\sqrt{P_0}(1+\frac{2(1-2a)\cosh \left(\mathrm{bz}\right)+\mathrm{ib}\sinh \left(\mathrm{bz}\right)}{\sqrt{2a}\cos \left(\mathrm{\ω\τ}\right)-\cosh \left(\mathrm{bz}\right)})e^{\mathrm{iz}}---\left(2\right)$

Here P ₀the average power of injecting field, distance z=(ξ-ξ ₀)/L _nLnormalization is in non-linear length L _nL=T ₀ ²/ | β ₂|, time scale T ₀=(| β ₂|/γ P ₀) ^1/2, ξ here ₀it is a real parameter.ω is modulating frequency, ω _c=(4 γ P ₀/ | β ₂|) ^1/2=2/T ₀.A, for the unstable gain of modulation, meets 2a=1-(ω/ω _c) ², scope is at 0 < a < 1/2.Parameter determine unstable Modulation growth.

Can obtain initial shooting conditions by Akhmediev breathing solution ψ (α, ξ, τ) is carried out to initial linear processing at ξ=0 place, form is:

$\mathrm{\&psi;}(0,\mathrm{\&tau;})=\sqrt{P_0}[1+\mathrm{\&delta;}\cos \left(\mathrm{\&omega;\&tau;}\right)]e^{{-\mathrm{i\&xi;}}_0}---\left(3\right)$

Here here (3) formula representative be that weak periodic modulation on a continuous wave excites, as shown in Figure 5, wherein parameter is P ₀=1W, ξ ₀=5 and α=0.25.Here, when α value is different, represented the modulating frequency difference of initial period modulation, the repetition rate difference of the final high power pulse string producing.α value is less, and the high power pulse string repetition rate of generation is higher.In practical application, can use continuous wave laser, phase-modulator and intensity modulator produce so initial excitation pulse, realize by Fig. 1 shown device.By the adjusting of intensity modulator beat frequency is realized to the periodic modulation to continuous wave different frequency.

The continuous wave that solution of equation (2) formula ψ (α, ξ, τ) has represented weak modulation, in the time that nonlinear optical fiber transmits, can be collapsed into the evolutionary process of the high power pulse string of a continuous wave background, as shown in Figure 6, Figure 7.Here α=0.25.Fig. 7 has provided the high power pulse string with continuous wave background pedestal forming apart from ξ=4.1km maximum compression place.But, from Fig. 6, can find out, after ξ=4.1km, this high power pulse string, under the modulational instability effect of continuous wave background, can be very soon decay get back to original state, be can not be continual and steady transmission.Therefore need to consider to eliminate this continuous wave background pedestal.

From (2) formula, can find out, this background wave is temporal evolution not, but along with changing apart from ξ, the expression formula of its time domain is

${\mathrm{\&psi;}}_B=\sqrt{P_0}[1-\frac{2(1-2a)\cosh \left(\mathrm{bz}\right)+\mathrm{ib}\sinh \left(\mathrm{bz}\right)}{\sqrt{2a}+\cosh \left(\mathrm{bz}\right)}]e^{\mathrm{iz}}---\left(4\right)$

Obviously, background wave expression (4) does not rely on time variable.We breathe (2) and deduct this continuous wave background (4) from the Akhmediev that has powerful connections, and just can be easy to draw the train of impulses of complete zero background:

${\mathrm{\&psi;}}_T(a,\mathrm{\&xi;},\mathrm{\&tau;})=\sqrt{P_0}\left\{\frac{\sqrt{2a}[2(1-2a)\cosh \left(\mathrm{bz}\right)+\mathrm{ib}\sinh \left(\mathrm{bz}\right)][1+\cos \left(\mathrm{\&omega;\&tau;}\right)]}{[\sqrt{2a}\cos \left(\mathrm{\&omega;\&tau;}\right)-\cosh \left(\mathrm{bz}\right)][\sqrt{2a}+\cosh \left(\mathrm{bz}\right)]}\right\}{e}^{\mathrm{iz}}---\left(5\right)$

Next (2) formula Akhmediev is breathed to solution ψ (α, ξ, τ) and carry out spectrum analysis, its spectrum signature can pass through Fourier expansion:

$\widetilde{\mathrm{\&psi;}}(\mathrm{\&xi;},\widetilde{\mathrm{\&omega;}})={\widetilde{\mathrm{\&psi;}}}_0\left(\mathrm{\&xi;}\right)+\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{\widetilde{\mathrm{\&psi;}}}_n\left(\mathrm{\&xi;}\right)\cos \left(n\widetilde{\mathrm{\&omega;}}\right),---\left(6\right)$

Therefrom, the evolution forms that obtains pumping wave and sideband amplitude is:

${\widetilde{\mathrm{\&psi;}}}_0\left(\mathrm{\&xi;}\right)=\sqrt{P_0}[1-\frac{2(1-2a)\cosh \left(\mathrm{bz}\right)+\mathrm{ib}\sinh \left(\mathrm{bz}\right)}{\sqrt{{\cosh }^2\left(\mathrm{bz}\right)-2a}}]e^{\mathrm{iz}},---\left(7\right)$

${\widetilde{\mathrm{\&psi;}}}_n\left(\mathrm{\&xi;}\right)=\sqrt{P_0}\frac{2(1-2a)\cosh \left(\mathrm{bz}\right)+\mathrm{ib}\sinh \left(\mathrm{bz}\right)}{\sqrt{{\cosh }^2\left(\mathrm{bz}\right)-2a}}{\left(\frac{\cosh \left(\mathrm{bz}\right)-\sqrt{{\cosh }^2\left(\mathrm{bz}\right)-2a}}{\sqrt{2a}}\right)}^{\left|n\right|}{e}^{\mathrm{iz}}.---\left(8\right)$

Wherein n=± 1, ± 2, ± 3 ... for integer.

By time domain and frequency domain character comparison, we can find that pumping wave part (7) formula in frequency domain is similar with continuous background ripple expression formula (4) in time domain, and this shows that (7) formula pumping wave amplitude has just represented in time domain that background wave is at the amplitude of frequency domain.If therefore the amplitude of (7) formula representative is filtered at frequency domain, the continuous background ripple of corresponding time domain part just can be eliminated.

Can obtain the high power pulse string with continuous wave background as shown in Figure 8 by initially exciting shown in Fig. 5, then the frequency spectrum of this high power pulse string be analyzed.Figure 10 has provided the high power pulse string spectrum intensity figure of this continuous wave background, and wherein the intensity of centre frequency has represented pumping wave intensity, and this pumping wave is at the ξ=ξ of maximum compression place ₀amplitude be

${\widetilde{\mathrm{\&psi;}}}_0(\mathrm{\&xi;}={\mathrm{\&xi;}}_0)=\sqrt{P_0}[1-2\sqrt{1-2a}]e^{\mathrm{iz}}---\left(9\right)$

The amplitude of adjacent sideband is with it

${\widetilde{\mathrm{\&psi;}}}_n(\mathrm{\&xi;}={\mathrm{\&xi;}}_0)=\sqrt{P_0}2\sqrt{1-2a}{\left(\frac{1-\sqrt{1-2a}}{\sqrt{2a}}\right)}^{\left|n\right|}{e}^{\mathrm{iz}}---\left(10\right)$

Wherein n=± 1, ± 2, ± 3 ... for integer.The amplitude of pumping wave and sideband is relevant with initial modulation parameter alpha.Here the pumping wave amplitude of centre frequency (9) formula representative is filtered accordingly, just can eliminate background wave.In practical filter, cannot realize the filtration to single-point frequency, be have certain frequency span filtration.Figure 11 has provided the high power pulse string frequency spectrum of continuous wave background through frequency centered by 1550nm, the result that the spectrum width pump light respective strengths frequency spectrum of 1nm filters.Like this, after filtering out main centre frequency pumping wave intensity in frequency domain, the pedestal of the continuous wave background in time domain will cancellation, obtains the high power pulse string of zero background, as shown in Figure 9.In the time that actual tunable optical filter filters, can, according to the amplitude of theoretical (7) formula representative, determine the centre frequency intensity of filtering, thereby realize, the effective background of the high power pulse string of continuous wave background is eliminated.Here when the frequency span of filtration is narrower, it is cleaner that the continuous wave background in time domain is eliminated, and the effect of generation is better.The high power pulse string of zero background obtaining so just can be in optical fiber stable transfer, as shown in figure 12.Figure 12 has provided by frequency spectrum and has filtered the evolutionary process that produces stable transfer high power pulse string.Figure 13 has provided the circle of equal altitudes of evolutionary process.

Further, continuous wave background high power pulse string is divided into three beams, wherein three beams inputs to an optical sampling oscillograph; To be divided into three beams by the train of impulses of optics tunable band-stop filter, the first bundle is as output beam, and the second bundle inputs to optical spectrum analysis instrument, and three beams inputs to optical sampling oscillograph; Detect the high power pulse string that obtains maximum compression place and have background by optical sampling oscillograph; Whether the background wave of observing the train of impulses after optics tunable band-stop filter filters by optical spectrum analysis instrument and optical sampling oscillograph is filtered; If be not filtered, regulated the wavelength-filtered of optics tunable band-stop filter and/or filter spectrum intensity, until the background wave of train of impulses is filtered completely; The high power pulse that zero background obtaining can be transmitted is input in single mode delivery optical fiber and transmits, from single mode delivery optical fiber, draw light beam and input to optical sampling oscillograph simultaneously, the mode of utilizing optical fiber gap to block, carries out Real-Time Monitoring to high power pulse string stable transfer.

Adopt optical spectrum analysis instrument to carry out spectrum analysis to high power pulse string, analyze centre frequency feature; According to result of spectrum analysis, determine centre frequency, regulate filtered band centre frequency and the intensity of optics tunable band-stop filter, the centre frequency part of maximum compression pulse is filtered, filter out the background wave part in time domain, obtain the high power pulse of zero background.Optical sampling oscillograph is for detection of the high power pulse string that obtains maximum compression place and have background; After frequency spectrum filters, optical sampling oscillograph is used for observing the filter effect of continuous wave, and suitably regulates optics adjustable filter frequency span and intensity according to filter effect, and background wave is eliminated.

The device that a kind of generation of the present invention can be transmitted high power pulse string is realized by the following technical solutions: a kind of generation can be transmitted the device of high power pulse string, comprises continuous wave laser, is connected in turn phase-modulator, intensity modulator and the Erbium-Doped Fiber Amplifier (EDFA) of continuous wave laser exit end by optical fiber; The exit ports of Erbium-Doped Fiber Amplifier (EDFA) is connected with single-mode fiber; The exit ports of single-mode fiber is provided with the first beam splitter, and the first exit end of the first beam splitter is provided with optics tunable band-stop filter; The second exit end of the first beam splitter is connected with optical spectrum analysis instrument by optical fiber.

The 3rd exit ports of the first beam splitter is connected with an optical sampling oscillograph; The exit end of optics tunable band-stop filter is connected with the second beam splitter, and the first exit end of the second beam splitter is connected with single mode delivery optical fiber; The second exit end of the second beam splitter is connected with another input end of optical spectrum analysis instrument; The 3rd exit end of the second beam splitter is connected with oscillographic the second input end of optical sampling; Single mode delivery optical fiber is connected with the 3rd beam splitter, and an exit end of the 3rd beam splitter is connected with oscillographic the 3rd input end of optical sampling.

The method of the invention and device can be removed continuous background ripple, obtain the high-power train of impulses of zero background.The present invention is simple and direct, efficient, and to high power pulse in optical fiber communication, transmission has important using value.

Brief description of the drawings

Fig. 1 is the Experimental equipment that the present invention produces continuous wave background high power pulse string in nonlinear optical fiber.

Fig. 2 eliminates continuous background ripple to produce stable transfer high power pulse string Experimental equipment.

Fig. 3 is the concrete structure schematic diagram one of Fig. 2 equipment therefor.

Fig. 4 is the concrete structure schematic diagram two of Fig. 2 equipment therefor.

Fig. 5 is initial shooting conditions: the continuous wave of weak periodic modulation.

Fig. 6 is the evolutionary process that produces continuous wave background train of impulses (limited background orphan).

Fig. 7 is the evolutionary process circle of equal altitudes that produces continuous wave background train of impulses.

Fig. 8 frequency spectrum has continuous wave background high power pulse string (maximum compression pulse) time domain before filtering distributes.

Fig. 9 frequency spectrum obtains zero background high power pulse string time domain after filtering distributes.

Figure 10 frequency spectrum has the high power pulse string frequency domain intensity distributions of continuous wave background before filtering.

The frequency domain intensity distributions of the high power pulse string of zero background after Figure 11 frequency spectrum filters.

Figure 12 filters the evolutionary process that produces stable transfer high power pulse string by frequency spectrum.

Figure 13 filters the evolutionary process circle of equal altitudes that produces stable transfer high power pulse string by frequency spectrum.1-continuous wave laser, 2-phase-modulator, 3-intensity modulator, 4-Erbium-Doped Fiber Amplifier (EDFA), 5-single-mode fiber, 6-the first beam splitter, 7-optics tunable band-stop filter, 8-optical spectrum analysis instrument, 9-optical sampling oscillograph, 10-the second beam splitter, 11-single mode delivery optical fiber, 12-the 3rd beam splitter.

Embodiment

Generation can be transmitted a method for high power pulse string, comprises the following steps: (a) produce a branch of continuous wave background high power pulse string; (b) this continuous wave background high power pulse string is at least divided into two bundles, the first bundle inputs in an optical spectrum analysis instrument 8, and the second bundle inputs to an optics tunable band-stop filter 7; Described optics tunable band-stop filter 7 is the adjustable filters with narrow-band band-elimination filtering function; (c) analyze the wavelength of the pumping wave of continuous wave background high power pulse string centre frequency representative according to optical spectrum analysis instrument 8, and by regulating optics tunable band-stop filter 7 to determine the centre wavelength that needs filtration, the centre frequency part background wave of continuous wave background high power pulse string is filtered, obtain the high power pulse string that zero background can be transmitted.

Continuous wave background high power pulse string is divided into three beams, and wherein three beams inputs to an optical sampling oscillograph 9; To be divided into three beams by the train of impulses of optics tunable band-stop filter 7, the first bundle is as output beam, and the second bundle inputs to optical spectrum analysis instrument 8, the three beams and inputs to optical sampling oscillograph 9; Detect the high power pulse string that obtains maximum compression place and have background by optical sampling oscillograph 9; Whether the background wave of observing the train of impulses after optics tunable band-stop filter 7 filters by optical spectrum analysis instrument 8 and optical sampling oscillograph 9 is filtered; If effectively do not filtered, regulate the wavelength-filtered of optics tunable band-stop filter 7 and/or filter spectrum intensity, until the background wave of train of impulses is filtered completely; The high power pulse that zero background obtaining can be transmitted is input to transmission in single mode delivery optical fiber 11, from single mode delivery optical fiber 11, draw light beam and input to optical sampling oscillograph simultaneously, the mode of utilizing optical fiber gap to block, carries out Real-Time Monitoring to high power pulse string stable transfer.

Described optics tunable band-stop filter 7 comprises collimation lens 7a, the optical filter 7b and the condenser lens 7c that are positioned in turn in light path; Described optical filter 7b is an adjustable narrow-band band-elimination optical filter; By regulating the incident angle between optical filter 7b and continuous wave background high power pulse string, just can select to need the background wave wavelength of filtration, the centre frequency part background wave of continuous wave background high power pulse string is filtered, obtain the high power pulse string that zero background can be transmitted.As shown in Figure 3.Optical filter is an adjustable narrow-band band-elimination optical filter, when making, on glass substrate, apply the (bichromate gelatin) that one deck has reflection holography diffracting layer, on (bichromate gelatin) layer, be coated with epoxy resin layer, and bonding is fixed mounting glass on epoxy resin layer, the requirement of filtering to reach narrow-band band-elimination.Simultaneously by regulate optical filter and light beam between incident angle, can select need filter background wave wavelength.By changing thickness or the refractive index of optical filter coating, change corresponding intensity filter.

The wavelength of the pumping wave that analyzes centre frequency representative by optical spectrum analysis instrument, and by regulate optical filter and light beam between incident angle determine the centre wavelength that needs filtration.By the spectrum intensity that analyzes pumping wave of optical spectrum analysis instrument, according to theoretical result of calculation, by the refractive index difference of optical filter coating, change corresponding intensity filter, obtain suitable optical filter.After such optical filter, background wave will be filtered, and produces the high power pulse string of zero background.

Described optics tunable band-stop filter 7 adopts long period fiber grating manifold type rejection filter; By selecting different fiber grating length, chirp coefficient and fibre cladding thermo-optic effect coefficient, background wave wavelength and the loss spectra intensity that can regulate selection to filter, realize the filtration of the centre frequency part background wave of continuous wave background high power pulse string, obtain the high power pulse string that zero background can be transmitted.As shown in Figure 4.Described long period fiber grating is coupled by preparing the fibre core basic mode of the specific wavelength (resonance background wave wavelength) that can make to meet phase-matching condition and the cladding mode of symport, the continuous background wave energy of forward transmission is coupled in the cladding mode of symport, realizes the function that background wave is filtered in band resistance.The SMF-28 optical fiber of the design of long period fiber grating based on common, or dispersion shifted optical fiber is made.The grating cycle is tens or hundreds of micron.By selecting different fiber grating length, chirp coefficient and fibre cladding thermo-optic effect coefficient, can flexible select background wave wavelength and the loss spectra intensity that need to filter.

Generation can be transmitted a device for high power pulse string, comprises continuous wave laser 1, is connected in turn phase-modulator 2, intensity modulator 3 and the Erbium-Doped Fiber Amplifier (EDFA) 4 of continuous wave laser 1 exit end by optical fiber; The exit ports of Erbium-Doped Fiber Amplifier (EDFA) 4 is connected with single-mode fiber 5; The first exit end that the exit ports of single-mode fiber 5 is provided with the first beam splitter 6, the first beam splitters 6 is provided with optics tunable band-stop filter 7; Described optics tunable band-stop filter 7 is the adjustable filters with narrow-band band-elimination filtering function; The second exit end of the first beam splitter 6 is connected with optical spectrum analysis instrument 8 by optical fiber.

The 3rd exit ports of the first beam splitter 6 is connected with an optical sampling oscillograph 9; The first exit end that the exit end of optics tunable band-stop filter 7 is connected with the second beam splitter 10, the second beam splitters 10 is connected with single mode delivery optical fiber 11; The second exit end of the second beam splitter 10 is connected with another input end of optical spectrum analysis instrument 8; The 3rd exit end of the second beam splitter 10 is connected with the second input end of optical sampling oscillograph 9; The exit end that single mode delivery optical fiber 11 is connected with the 3rd beam splitter 12, the three beam splitters 12 is connected with the 3rd input end of optical sampling oscillograph 9.

Described optics tunable band-stop filter 7 comprises collimation lens 7a, the optical filter 7b and the condenser lens 7c that are positioned in turn in light path; Described optical filter 7b is an adjustable narrow-band band-elimination optical filter.

Described optics tunable band-stop filter adopts long period fiber grating manifold type rejection filter.

Described single-mode fiber 5 and single mode delivery optical fiber 11 anomalous dispersion β ₂for-21.4ps ²/ m, non-linear γ is 1.2W ^-1km ^-1, loss is 0.19dB/km, length is 8.3 kilometers.

Performing step in practical application: penetrate continuous wave by an exocoel 1550nm continuous wave laser (Photline Technologies ICB SoFast ModBox) 1, widen laser linewidth to about 43MHz through phase-modulator 2, avoid it that Brillouin scattering occurs, this continuous wave, through intensity modulator 3, is clapped the Sine Modulated of carrying out driving by 25G hertz radio frequency afterwards; Modulated amplitude is that overall delustring appears in the inhibition of random off resonance; Then inputting an Erbium-Doped Fiber Amplifier (EDFA) (EDFA-IPG model EAD-1-C-PM) 4 allows average power rise to 28dBm; Then input end anomalous dispersion β ₂for-21.4ps ²/ m, non-linear γ is 1.2W ^-1km ^-1, the standard single-mode fiber 5 that loss is 0.19dB/km, after 4.1 kilometers, reinvents Sine Modulated continuous wave into continuous wave background high power pulse string.The continuous wave background high power pulse string of output is through the first beam splitter 6, separating light beam detects and obtains maximum compression pulse through the optical sampling oscillograph (OSO-Picosolve PSO-101) 9 of Picosecond, and utilize the optical spectrum analysis instrument (OSA-Yokogawa-AQ6370) 8 of high dynamic range, another bundle high power pulse string separating is carried out to spectrum analysis, analyze centre frequency feature; The three-beam separating is according to result of spectrum analysis, adopt optics tunable band-stop light filter 7 to filter the centre frequency part of maximum compression pulse, filter out the background wave part in time domain, obtain the high power pulse of zero background, by the high power pulse of this zero background again through the second beam splitter 10, after beam splitting, access respectively optical sampling oscillograph 9 and optical spectrum analysis instrument 8, utilize optical sampling oscillograph 9 observation background ripples whether to be filtered; If filter effect is undesirable, in conjunction with the Spectrum Relationship of optical spectrum analysis instrument 8 front and back, by filtered band intensity and the wavelength of collimation optical tunable band-stop light filter 7, obtain zero comparatively desirable background high power pulse string; Afterwards the zero background high power pulse string obtaining is input to transmission in the single mode delivery optical fiber 11 identical with single-mode fiber 5 specifications, the mode of utilizing optical fiber gap to block, beam separation between transmission period is gone out to a branch of being linked in optical sampling oscillograph 9, the stable transfer of high power pulse string is carried out to Real-Time Monitoring.

Claims (10)

1. generation can be transmitted a method for high power pulse string, it is characterized in that, comprises the following steps: (a) produce a branch of continuous wave background high power pulse string; (b) this continuous wave background high power pulse string is at least divided into two bundles, the first bundle inputs in an optical spectrum analysis instrument (8), and the second bundle inputs to an optics tunable band-stop filter (7); Described optics tunable band-stop filter (7) is the adjustable filter with narrow-band band-elimination filtering function; (c) analyze the wavelength of the pumping wave of continuous wave background high power pulse string centre frequency representative according to optical spectrum analysis instrument (8), and by regulating optics tunable band-stop filter (7) to determine the centre wavelength that needs filtration, the centre frequency part background wave of continuous wave background high power pulse string is filtered, obtain the high power pulse string that zero background can be transmitted.

2. a kind of generation as claimed in claim 1 can be transmitted the method for high power pulse string, it is characterized in that, continuous wave background high power pulse string is divided into three beams, and wherein three beams inputs to an optical sampling oscillograph (9); To be divided into three beams by the train of impulses of optics tunable band-stop filter (7), the first bundle is as output beam, and the second bundle inputs to optical spectrum analysis instrument (8), and three beams inputs to optical sampling oscillograph (9); Detect the high power pulse string that obtains maximum compression place and have background by optical sampling oscillograph (9); Whether the background wave of observing the train of impulses after optics tunable band-stop filter (7) filters by optical spectrum analysis instrument (8) and optical sampling oscillograph (9) is filtered; If be not filtered, regulated the wavelength-filtered of optics tunable band-stop filter (7) and/or filter spectrum intensity, until the background wave of train of impulses is filtered completely; The high power pulse that zero background obtaining can be transmitted is input to transmission in single mode delivery optical fiber (11), from single mode delivery optical fiber (11), draw light beam and input to optical sampling oscillograph (9) simultaneously, the mode of utilizing optical fiber gap to block, carries out Real-Time Monitoring to high power pulse string stable transfer.

3. a kind of generation as claimed in claim 1 or 2 can be transmitted the method for high power pulse string, it is characterized in that, described optics tunable band-stop filter (7) comprises the collimation lens (7a), optical filter (7b) and the condenser lens (7c) that are positioned in turn in light path; Described optical filter (7b) is an adjustable narrow-band band-elimination optical filter; By regulating the incident angle between optical filter (7b) and continuous wave background high power pulse string, just can select to need the background wave wavelength of filtration, the centre frequency part background wave of continuous wave background high power pulse string is filtered, obtain the high power pulse string that zero background can be transmitted.

4. a kind of generation as claimed in claim 1 or 2 can be transmitted the method for high power pulse string, it is characterized in that, described optics tunable band-stop filter (7) adopts long period fiber grating manifold type rejection filter; By selecting different fiber grating length, chirp coefficient and fibre cladding thermo-optic effect coefficient, background wave wavelength and the loss spectra intensity that can regulate selection to filter, realize the filtration of the centre frequency part background wave of continuous wave background high power pulse string, obtain the high power pulse string that zero background can be transmitted.

5. a generation can be transmitted the device of high power pulse string, be used for realizing the method for claim 1, comprise continuous wave laser (1), be connected in turn phase-modulator (2), intensity modulator (3) and the Erbium-Doped Fiber Amplifier (EDFA) (4) of continuous wave laser (1) exit end by optical fiber; The exit ports of Erbium-Doped Fiber Amplifier (EDFA) (4) is connected with single-mode fiber (5); It is characterized in that, the exit ports of single-mode fiber (5) is provided with the first beam splitter (6), and the first exit end of the first beam splitter (6) is provided with optics tunable band-stop filter (7); Described optics tunable band-stop filter (7) is the adjustable filter with narrow-band band-elimination filtering function; The second exit end of the first beam splitter (6) is connected with optical spectrum analysis instrument (8) by optical fiber.

6. a kind of generation as claimed in claim 5 can be transmitted the device of high power pulse string, it is characterized in that, the 3rd exit ports of the first beam splitter (6) is connected with an optical sampling oscillograph (9); The exit end of optics tunable band-stop filter (7) is connected with the second beam splitter (10), and the first exit end of the second beam splitter (10) is connected with single mode delivery optical fiber (11); The second exit end of the second beam splitter (10) is connected with another input end of optical spectrum analysis instrument (8); The 3rd exit end of the second beam splitter (10) is connected with the second input end of optical sampling oscillograph (9); Single mode delivery optical fiber (11) is connected with the 3rd beam splitter (12), and an exit end of the 3rd beam splitter (12) is connected with the 3rd input end of optical sampling oscillograph (9).

7. a kind of generation as described in claim 5 or 6 can be transmitted the device of high power pulse string, it is characterized in that, described optics tunable band-stop filter (7) comprises the collimation lens (7a), optical filter (7b) and the condenser lens (7c) that are positioned in turn in light path; Described optical filter (7b) is an adjustable narrow-band band-elimination optical filter.

8. a kind of generation as described in claim 5 or 6 can be transmitted the device of high power pulse string, it is characterized in that, described optics tunable band-stop filter (7) adopts long period fiber grating manifold type rejection filter.

9. a kind of generation as claimed in claim 7 can be transmitted the device of high power pulse string, it is characterized in that described single-mode fiber (5) and single mode delivery optical fiber (11) anomalous dispersion β ₂for-21.4ps ²/ m, non-linear γ is 1.2W ^-1km ^-1, loss is 0.19dB/km, length is 8.3 kilometers.

10. a kind of generation as claimed in claim 8 can be transmitted the device of high power pulse string, it is characterized in that described single-mode fiber (5) and single mode delivery optical fiber (11) anomalous dispersion β ₂for-21.4ps ²/ m, non-linear γ is 1.2W ^-1km- ^1,loss is 0.19dB/km, and length is 8.3 kilometers.