CN107732642A - Produce the device and non-linear laser crystal preparation method of the visible super continuous laser near infrared band wideband adjustable - Google Patents
Produce the device and non-linear laser crystal preparation method of the visible super continuous laser near infrared band wideband adjustable Download PDFInfo
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- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 10
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 4
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
- G02F1/3534—Three-wave interaction, e.g. sum-difference frequency generation
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/0005—Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
Abstract
The present invention provides a kind of device for producing the visible super continuous laser near infrared band wideband adjustable, including pump light source and non-linear laser crystal, it is characterized in that, the pump light source is had nearly 100nm bandwidth by the frequency for the femtosecond pulse that near-infrared femtosecond pulse light source and the pump light source provide, and the femtosecond pulse has the characteristics of high-peak power；The non-linear laser crystal is made using ferroelectric crystal materials, and the non-linear laser crystal includes a series of cellular, and a series of length of the cellulars in cellular on optical propagation direction changes along optical propagation direction according to the rule that continuous chirp changes.The present invention can produce tunable super continuous, the completely relevant laser of visible to infrared 400 900nm band broadbands；The advantages of with structure-controllable, easily prepared, flexible design；Energy conversion efficiency is high, laser spectrum broadband is super continuous and device size is small.
Description
Technical field
The present invention relates to laser technology field, specifically, is produced the present invention relates to one kind visible wide near infrared band
The preparation method of device and corresponding non-linear laser crystal with tunable super continuous laser.
Background technology
Dependence is produced from laser, it has huge application value in fields such as national defence, medical treatment, industry, communications.Recent decades
Come, laser technology obtains huge development.But the frequency of laser output is limited by gain media energy level, it is impossible to is produced
The output of optional frequency.Finding outside new laser crystal material, people generally require to utilize nonlinear frequency conversion technology
(frequency multiplication and frequency, difference frequency, parameter amplification etc.) is come the laser of frequency needed for obtaining.
During laser produces, most crucial is to solve the problems, such as the phase matched in non-linear process, yet with non-thread
Dispersion be present in property material, phase matched generally can not be met automatically.In actual applications, people generally utilize crystal
Dispersion of the birefringent characteristic to crystal compensates, so as to reach the purpose of phase matched.Walked off however, birefringence matching is present
The limitations such as effect, nonlinear factor be small so that its practical application is restricted.
In order to solve this problem, there has been proposed non-linear photon crystal, (i.e. the symbol of nonlinear factor has the cycle
Property change artificial microstructure crystal material) concept, quasi-phase matched is realized with this.Quasi-phase matching is to pass through week
Change to phase property the spontaneous polarization direction of crystal to rearrange phase of light wave, so as to the phase misalignment during compensating non-linear
Match somebody with somebody, it considerably increases flexibility and the controllability of second nonlinear process, and non-linear frequency has been started with the brand-new way of thinking
The rate switch technology revolutionary new stage, the development of laser technology has also been promoted significantly.
The preparation of non-linear photon crystal needs to use ferroelectric crystal materials, common are lithium niobate, lithium tantalate, phosphoric acid oxygen
Titanium potassium crystal etc..Iron electric polarization direction represents the sign symbol (corresponding respectively to positive farmland and negative farmland) of nonlinear factor, ferroelectricity
The spontaneous polarization direction of crystal overcomes the coercive field inside ferroelectric crystal easily by extra electric field and reversed, and applies additional
Electric field will enable to the nonlinear factor reindexing (such as from positive to negative) of ferroelectric crystal.When the electric field applied is in space
When upper period profile, it becomes possible to the periodically positive and negative distribution of the nonlinear factor of regulation and control ferroelectric non-linear crystals, from
And non-linear photon crystal is constructed, and then realize quasi-phase matched.
Since the concept of quasi-phase matching is suggested, people's design is prepared for diversified cycle, paracycle
Or aperiodic non-linear photon crystal come tackle the nonlinear optical frequency of diversification conversion application demand, such as utilize
Monolithic nonlinear crystal realizes the quasi-phase matched of two or more wavelength simultaneously.Due to existing non-linear photon crystal knot
Structure can not regulate and control to the phase-matching condition in a variety of non-linear process of different wave length composition simultaneously, and this is greatly limited
The energy utilization efficiency of the non-linear conversion process of broad band laser, the technology for also constraining nonlinear optics swash to femtosecond pulse
The application extension of the ultra wide band laser technology such as light.For birefringence matching technique, phase matched that birefringece crystal can provide
Bandwidth it is more limited, one block of birefringece crystal can only be applied to the continuous laser or narrow-band impulse laser of some specific frequency
Add efficient nonlinear frequency conversion, thus the super continuous laser output in broadband can not be obtained.
Super continuous laser source has the advantages that brightness is high, power is strong, frequency coverage is wide, basic science, information,
The fields such as medical treatment, environment measuring have a wide range of applications.At present, the method for the super continuous laser source of generation is mainly in the world
Interacted using photonic crystal fiber and high-power ultra-short pulse laser, opened up by various third-order nonlinear optical effects
The frequency range of wide pumping laser, but to still suffer from conversion efficiency not high for the program, its spectrum widening scope is only in visible spectrum
Wave band or in infrared spectrum wave band, still suffers from not big enough the determination of broadening.In addition, the super continuous laser source in the program is not
Relevant LASER Light Source completely, that is to say, that radiant light is relevant laser inside specific arrowband, but different colours
There is no good coherence between radius, which limits the application of the light source.Such as the super company cannot be utilized
Continuous LASER Light Source produces ultra-short pulse laser.
Therefore, currently there is an urgent need to a kind of high conversion efficiency, it is completely relevant, can produce it is visible wide near infrared band
Solution with tunable super continuous laser.
The content of the invention
The task of the present invention be to provide a kind of high conversion efficiency, it is completely relevant, can produce it is visible near infrared band
The solution of the super continuous laser of wideband adjustable.
According to an aspect of the invention, there is provided it is a kind of produce it is visible super continuous near infrared band wideband adjustable
The device of laser, including pump light source and non-linear laser crystal, it is characterised in that the pump light source swashs near infrared band
(spectral bandwidth of near-infrared femtosecond pulse is about hundred nanometers to radiant, and the femtosecond pulse has high-peak power
The characteristics of, its peak power can be far smaller than that the optical damage power threshold in crystalline material under continuous laser pumping, can
Reach GW/cm2Magnitude)；
The non-linear laser crystal includes a series of cellular, a series of length of the cellulars on optical propagation direction
Change along optical propagation direction according to continuous chirp and change.
Wherein, the non-linear laser crystal is according to formula Λ (z)=Λ0/[1+(DgΛ0Z/2 π)], it is each to determine
The length of the cellular in a z-direction, wherein z represent the position coordinates on the z directions corresponding to some cellular, and z directions are
The optical propagation direction, wherein Λ0For the pole required for the frequency multiplication process corresponding to the centre wavelength of the femtosecond pulse
Change cycle, DgFor chirp degree.
Wherein, the position coordinates corresponding to described cellular on z directions is the coordinate of the section start of the cellular.
Wherein, the polarization cycle Λ0, chirp degree DgCombinations of values make the reciprocal lattice vector of the non-linear laser crystal be in
It is now several reciprocal lattice vector bands for being distributed in diverse location.
Wherein, the super continuous laser in broadband that several described reciprocal lattice vector bands correspond respectively to different-waveband participates in non-thread
Resistant frequency transfer process, and each reciprocal lattice vector band effectively compensates for the super continuous laser participation in broadband that there is continuous frequency spectrum to be distributed
Nonlinear frequency conversion process.
Wherein, several described reciprocal lattice vector bands correspond respectively to the secondary and triple-frequency harmonics non-linear of pumping optical band
Frequency conversion, effective phase compensation is provided for these nonlinear frequency conversions.Because the reciprocal lattice vector band of design is very wide, Neng Goushi
Now output laser tunes in very wide frequency spectrum.Due to Third-order nonlinearity, the secondary and spectrum of triple-frequency harmonics also by broadening,
It can be covered after combination visible near infrared band.
Wherein, the non-linear laser crystal is made using ferroelectric crystal materials, and the ferroelectric crystal materials are lithium niobate
Crystalline material, magnesium-doped lithium niobate crystal or lithium tantalate material.
According to another aspect of the present invention, a kind of preparation method of non-linear laser crystal, including following step are additionally provided
Suddenly：
1) mask plate with specific pattern is prepared, the pattern on the mask plate corresponds to the non-linear laser crystal
A series of cellulars；A series of length on optical propagation direction of cellulars becomes along optical propagation direction according to continuous chirp
Change and change；
2) in the surface spin coating photoresist of non-linear laser crystal, the pattern of mask plate is shifted and is solidificated in photoresist
On；
3) non-linear laser crystal two sides is contacted with conducting medium respectively, then by conducting medium on crystal following table
Face adds the electric field more than crystal coercive field so that does not have the region internal poles for coating photoresist on the non-linear laser crystal
Change direction to reverse, and the region for remaining with photoresist remains in that original polarised direction.
Wherein, the step 1) also includes：Attempt different polarization cycle Λ0, chirp degree DgWith length L combinations of values,
According to formula Λ (z)=Λ0/[1+(DgΛ0Z/2 π)], it is determined that the polarization cycle of the cellular corresponding to various parameters combinations of values
Sequence, the reciprocal lattice vector band combination corresponding to these cellular polarization cycle sequences is then simulated, and then simulate final output
The wave band of laser simultaneously preferably goes out parameter values combination, and combining corresponding cellular polarization cycle sequence according to the parameter values determines
Pattern on mask plate.
Wherein, the step 1) also includes：Analyze the phase benefit that every kind of reciprocal lattice vector band combines provided non-linear process
Repay, and then simulate the wave band of the laser of final output, if the wave band of the laser of the final output simulated is continuous and energy
Enough cover it is visible near infrared spectrum wave band, then judge corresponding to parameter values combination meet the requirements, according to the parameter values group
Cellular polarization cycle sequence corresponding to closing determines the pattern on mask plate.
Compared with prior art, the present invention has following technique effect：
1st, the present invention can produce the visible super continuous laser near infrared band wideband adjustable.
2nd, crystal of the invention has the advantages of structure-controllable, easily prepared, flexible design.
3rd, the energy conversion efficiency of laser generator of the invention is high, laser spectrum ultra wide band and super continuous.
4th, the device size of super continuous laser generation device of the invention is small.
Brief description of the drawings
Hereinafter, embodiments of the invention are described in detail with reference to accompanying drawing, wherein：
Fig. 1 shows the spectral distribution graph of the pumping near-infrared femtosecond pulse in one embodiment of the invention, pumping
Center wavelength of light can be modulated 1500nm by 1200nm, and mean power is each about 40-69mW；
Fig. 2 shows a kind of discrete reciprocal lattice vector distribution map of cycle non-linear photon crystal of the prior art；
Fig. 3 shows the design diagram of the chirp non-linear photon crystal in one embodiment of the invention；
Fig. 4 shows the reciprocal lattice vector band distribution map of the non-linear photon crystal in one embodiment of the invention；It is wherein vertical to sit
Effective nonlinear factor is designated as, abscissa is the numerical value of reciprocal lattice vector；
Fig. 5-Figure 11 shows the visible to near-infrared of the non-linear photon crystal output laser of one embodiment of the invention
Spectral distribution graph, illustration correspond to respectively the embodiment of the present invention chirp lithium niobate non-linear photon crystal output laser beam
Photo；To meet the substantive requirements of form of patent document, it should be noted that, the photo has been converted into black-and-white photograph, and its artwork is colored
Picture；
Figure 12 shows the laser beam of the chirp lithium niobate non-linear photon crystal output of one embodiment of the invention
Gamut range, the centre wavelength of pump light source corresponding to xxxnm representatives；To meet the substantive requirements of form of patent document, should be noted
It is that the photo has been converted into black-and-white photograph, its artwork is colour picture；
Figure 13 shows the surface spin coating photoresist in non-linear laser crystal, and the pattern of mask plate is shifted and is solidificated in
Schematic diagram on photoresist；
Figure 14 is shown adds the electric field more than crystal coercive field by conducting medium in crystal upper and lower surface, is formed positive and negative
The schematic diagram of the alternatively distributed structure on farmland；
Figure 15 show chirp non-linear photon crystal prepared by method based on above-described embodiment in light microscope
Under surface topography map；
Figure 16 shows the partial enlarged drawing of the surface topography of Figure 15 chirp non-linear photon crystal.
Embodiment
According to one embodiment of present invention, there is provided it is a kind of produce it is visible super continuous sharp to near-infrared wideband adjustable
The device of light, the device include near-infrared femtosecond pulse light source and chirp non-linear photon crystal.Wherein, near-infrared femtosecond
The spectrum for the femtosecond pulse that pulsed laser light source is provided as pump light source, the pump light source has nearly hundred nanometers of bandwidth,
The femtosecond pulse has the characteristics of high-peak power.In the present embodiment, the centre wavelength scope of pump light is 1200-
1500nm continuously adjustabes, spectrum width is about 100nm, single pulse energy about 50uJ, Fourier's limit about 50fs of pulse width, pulse
Repetition rate is 1kHz, and corresponding mean power is about 50mW.The pulse laser is the pump light in a completely relevant broadband.
Fig. 1 shows the spectral distribution graph of the pumping near-infrared femtosecond pulse in the present embodiment.In the present invention, as pump light
The parameters such as the single pulse energy of near-infrared femtosecond pulse, pulse length, pulse recurrence frequency, mean power, can also root
Adjusted according to actual conditions.
In the present embodiment, as reception pump light and exported visible near infrared band using chirp non-linear photon crystal
The non-linear photon crystal of the super continuous laser of wideband adjustable.Herein, non-linear laser crystal refers to laser frequency work(
The Nonlinear Superlattice crystal of energy.Chirp non-linear photon crystal is on the basis of cycle non-linear photon crystal, to polarization
Cycle applies suitable rule change, i.e., along optical propagation direction the length of polarization cycle is applied into continuous chirp change and shape
Into photonic crystal.For ease of understanding, cycle non-linear photon crystal is introduced first.
Traditional cycle non-linear photon crystal is formed by a series of cellular periodic arrangement.Each cellular includes one
Positive farmland and a negative farmland.Equal length of each cellular on optical propagation direction, such as each cellular is on optical propagation direction
Length is equal to the lattice period of non-linear photon crystal.The reciprocal lattice vector of cycle non-linear photon crystal is a series of period distances
Discrete lines, therefore the nonlinear frequency conversion for being only the laser of some wavelength provides effective phase compensation, respectively
Referred to as single order, second order, three ranks etc. quasi-phase matched.And non-linear photon crystal paracycle by two cellulars according to specific standard
Periodic mode arrangement forms, and its reciprocal lattice vector is a series of two sets of mutual independent discrete lines, and Fig. 2 shows a kind of typical week
The discrete reciprocal lattice vector distribution map of phase non-linear photon crystal.This reciprocal lattice vector distribution can only be simultaneously the sharp of certain two specific wavelength
The nonlinear frequency conversion of light provides effective phase compensation, swashs so non-linear photon crystal paracycle may not apply to broadband
The nonlinear frequency conversion process of light (such as femtosecond pulse).
The chirp non-linear photon crystal of the present embodiment is on the basis of cycle non-linear photon crystal, to polarization cycle
Apply suitable rule change, i.e., the length of polarization cycle is applied into continuous chirp along optical propagation direction changes.This implementation
In example, chirp non-linear photon crystal is made up of a series of cellular, wherein the length on the negative farmland of each cellular and positive farmland is simultaneously
Change causes the length of a series of cellular to meet the rule of chirp change.Fig. 3 shows that the chirp in the present embodiment is non-
The design diagram of linear photon crystal.With reference to figure 3, coordinate system is established, (i.e. pump light inputs with the high order end of photonic crystal
End) transmission direction of laser is z directions shown in Fig. 3.The length of described polarization cycle is exactly the cellular of photonic crystal in z side
Upward length (alternatively referred to as width), a series of length of cellulars in a z-direction changes along z directions according to continuous chirp
Rule and change, " continuous chirp change " is a series of length of cellulars in a z-direction in photonic crystal by small herein
The function curve value to big or descending changed along chirp.
From actual demand, the pole required for the frequency multiplication process corresponding to the centre wavelength of suitable pump light is first selected
Change periods lambda0, chirp degree DgWith sample length L (i.e. photonic crystal length), then according to Λ (z)=Λ0/[1+(DgΛ0z/2
π)], it is determined that each length of cellular in a z-direction, wherein z represent the position coordinates on the z directions corresponding to some cellular.
In the present embodiment, position coordinates corresponding to a cellular on z directions is the coordinate of the section start of the cellular, such as first member
The position coordinates of born of the same parents is 0, and the position coordinates of second cellular is Λ (0), the i.e. line of demarcation of first cellular and second cellular
The coordinate at place.
In the present embodiment, polarization cycle Λ0=2 π/Δ k0, Δ k0=4 π [n2(λ0)-n1(λ0)]/λ0, λ0It is Broadband pump
The centre wavelength of optical band, n1(λ0) expression wavelength is λ0Fundamental frequency light refractive index, n2(λ0) expression wavelength is λ0Light times
The refractive index of frequency light.Chirp degree DgFor 7.1, sample total length is 1.1cm.
The reciprocal lattice vector of chirp non-linear photon crystal with said structure and parameter is distributed as several reciprocal lattice vector bands, such as
Shown in Fig. 4.(such as femtosecond pulse swashs the super continuous laser in broadband that each reciprocal lattice vector band can effectively compensate for there is continuous frequency spectrum to be distributed
Light) the nonlinear frequency conversion process (such as frequency multiplication and frequency) that participates in.In addition, several reciprocal lattice vector bands can correspond respectively to difference
The nonlinear frequency conversion process (such as frequency multiplication and and frequency) that the super continuous laser in broadband of wave band participates in.
All reciprocal lattice vectors band synergy of chirp non-linear photon crystal, can meet the non-linear frequency in broadband range
Upper transfer process so that the generation of non-linear higher hamonic wave (2,3 subharmonic etc.) is possibly realized.The small band of reciprocal lattice vector numerical value
Support the harmonic conversion of low order time (2 times and part 3 times) (i.e. close to the B1 bands of the coordinate longitudinal axis), and the band that reciprocal lattice vector numerical value is big
(B2 bands) supports the harmonic conversion of 3 times.
The quasi-phase matched reciprocal lattice vector band required for more order harmonic generation processes, institute are provided due to above-mentioned photonic crystal
To produce the laser of 2 frequencys multiplication, base through frequency multiplication process in frequency multiplication of the crystals Jing Guo Ji Lian and with frequency process, such as basic frequency laser
Frequency laser and 2 double-frequency lasers pass through and frequency process produces 3 frequencys multiplication, export the harmonic wave of 2-3 times simultaneously from crystal exit ports.
In the present embodiment, B1 bands provide effective phase compensation for the frequency multiplication of pump light (fundamental frequency light) wave band, so as to obtain
The laser of frequency multiplication optical band.B1 and B2 bands for fundamental frequency light and frequency doubled light and provide effective phase compensation frequently, so as to obtain 3 times
The wave band of harmonic wave.Simultaneously because Third-order nonlinearity, pump light when crystal by also occurring broadening so that 2,3 times
Harmonic wave covers bigger frequency range.2,3 subharmonic make it cover 400- when passing through crystal also in broadening with caused by
900nm wave band.
Because B1 the and B2 bandwidth of design is very wide so that the super continuous laser of output can be adjusted in very wide spectral region
It is humorous, so as to adjust the colour gamut of output laser.
In the present embodiment, chirp non-linear photon crystal is made using lithium columbate crystal material.Lithium niobate is a kind of synthesis
The ferroelectric non-linear crystalline material of function admirable, nonlinear factor is big, and transparent scope is 310-5000nm, covers ultraviolet red into
Outer wave-length coverage.In other embodiments, chirp non-linear photon crystal can also use magnesium-doped lithium niobate crystal or tantalic acid
Crystalline lithium material makes.
Further, Fig. 5 to Figure 11 shows the light of the 400-900nm wave band of laser of the output of the sample of the present embodiment
Spectrum, 400-900nm wave bands can be completely covered by exporting the wavelength of laser, by adjusting the centre wavelength of pump light, can be changed
Export the colour gamut of laser.The color camera of light beam is as shown in the illustration in Fig. 5-Figure 11.Chirp non-linear photon crystal is exported
Pulse laser be the high performance completely relevant visible super continuous laser near infrared band wideband adjustable.
Figure 12 shows the gamut range of output laser, and the colour gamut of the output super continuous laser in broadband can be by changing pump light
Wavelength regulation.
In the present embodiment, the laser power of the 400-900nm wave bands of the output of chirp non-linear photon crystal is 8.38-
18.92mW or so, single pulse energy 8.38-18.92uJ.In view of the incident incomplete efficiency of transmission with exit ports of crystal
(74%), the near infrared pulsed laser of pumping is converted to visible super continuous sharp to near-infrared by chirp non-linear photon crystal
The efficiency of light is 20.7-30.4%, far above other schemes, such as photonic crystal fiber Supercontinuum source.
It should be noted that currently a popular photonic crystal fiber Supercontinuum source, because fiber lengths are 1 meter or so,
And optical fiber includes complicated porous micro-nano structure, larger inhomogeneities be present along the geometry in optical fiber direction and (is much larger than
Lithium columbate crystal material), such as many ups and downs trickle nanostructureds of hole side wall presence, there is strong diffusing scattering to light wave
Effect.A variety of third-order non-linears interaction (Self-phase modulation, four-wave mixing, the drawing occurred during such long range
Graceful scattering etc. process), have no idea to keep the coherence of pumping pulse laser so that caused Supercontinuum source is concerned with
Property much worse than pumping pulse laser coherence, also far below the pumping pulse laser and lithium niobate nonlinear crystal of the present embodiment
The coherence of super continuous laser caused by higher hamonic wave interaction, in addition, this method has to the stretching capability of laser spectrum
Limit, can not produce the super continuous laser of wide range in the present embodiment.Therefore this kind of Supercontinuum source is substantially the laser of partially coherent
Light source, it is not completely relevant LASER Light Source truly.And in the present embodiment, merely with monolithic nonlinear crystal just into
Work(realizes efficient completely relevant visible to the nearly outer tunable super continuous laser of wide range.
As it was noted above, in the aforementioned embodiment, chirp non-linear photon crystal is made up of a series of cellular, wherein respectively
The negative farmland of individual cellular and the length change on positive farmland cause the length of a series of cellular to meet the rule of chirp change.It is this
Chirp non-linear photon crystal structure is not unique.
In addition, as it was noted above, the reciprocal lattice vector of chirp non-linear photon crystal is distributed as several reciprocal lattice vector bands, these fall
The design of lattice vector band is not unique, wherein, the width (i.e. bandwidth) of band and the center of band, and between band-to-band
Every can flexible modulation as needed, as long as this series of reciprocal lattice vector band can correspond respectively to pump light (i.e. fundamental frequency light) wave band
Secondary and triple-frequency harmonics nonlinear frequency conversion (such as frequency multiplication and frequency etc.), be provided with for these nonlinear frequency conversions
The phase compensation of effect, and so that can be covered after the band combination of multiple harmonic whole visible to near-infrared 400-900nm ripples
Section, you can obtain the completely relevant super continuous laser in broadband.
Further, according to above-mentioned operation principle, additionally provided in one embodiment of the present of invention a kind of using additional
The method that electric field polarization method prepares chirp non-linear photon crystal, its main process are as follows：
(1) the pattern mask plate of chirp non-linear photon crystal is prepared using electron beam lithography.On the mask plate
Pattern corresponds to a series of cellulars, and the length of these cellulars in a z-direction can form continuous chirp change.Also, these yuan
Multiple reciprocal lattice vector bands corresponding to born of the same parents can be provided with to a variety of nonlinear changes of the femtosecond pulse of near infrared band respectively
The phase compensation of effect so that visible ray can be completely covered by the wave band of 2 times caused by a variety of nonlinear changes and 3 subharmonic
To near infrared band.
In one example, different polarization cycle Λ can be attempted0, chirp degree DgParameters such as (i.e. photonic crystal length)
Combination, according to aforementioned formula Λ (z)=Λ0/[1+(DgΛ0Z/2 π)], it is determined that being polarized corresponding to the cellular of various parameters combination
Periodic sequence, the reciprocal lattice vector band combination corresponding to these cellular polarization cycle sequences is then simulated, analyzes this reciprocal lattice vector band
The phase compensation of the provided non-linear process of combination, and then simulate the wave band of the laser of final output.If final output
Wave band it is continuous, and can covering visible light wave band, then judge corresponding to parameter combination meet the requirements, according to the parameter combination institute
Corresponding cellular polarization cycle sequence determines the pattern on mask plate.
(2) the pattern transfer of mask plate is being covered into the insulated photo-etching rubber on lithium niobate crystal chip surface using uv-exposure technology
On.By the process developed and be fixed, pattern solidifies on a photoresist, then in pattern applied atop good conductor, formation and Zhou
Sing the consistent electrode of non-linear photon crystal pattern.
Practical operation is as shown in figure 13, first one layer of the one side spin coating in nonlinear crystal 3 (i.e. non-linear photon crystal)
Photoresist layer 2, photoresist recycle uv-exposure technology, with ultraviolet light to being placed on covering above sample after heating, drying
Template 1 is irradiated, if photoresist 2 is positive photoresist (or negtive photoresist), the photoresist of light transmission part (or lightproof part) passes through
It development, will be removed after being fixed, the pattern on mask plate can be thus transferred on photoresist layer.
(3) as shown in figure 14, the two sides of nonlinear crystal 3 is contacted with conducting medium 4 respectively, then passes through conducting medium 4
The electric field more than the nonlinear crystalline material coercive field is added on crystal two sides, being alternately distributed for positive and negative farmland will be formed, in figure
White portion 32 represents positive farmland, and black region 31 represents negative farmland.Wherein, the region for not having photoresist 21 on crystal can pass through electricity
Stream, the voltage that outside applies are acted on crystalline material so that polarised direction reverses.And the region for remaining with photoresist 21 is being led
Have between dielectric 4 and nonlinear crystal 3 and isolate as the photoresist 21 of insulating barrier, can not stored charge, no voltage acts on
On nonlinear crystal 3, therefore region corresponding to nonlinear crystal 3 remains in that the symbol of original polarised direction and nonlinear factor
Number.So, it is formed the alternatively distributed structure on positive and negative farmland.In the structure, the positive and negative farmland of each pair forms a cellular, a series of
Cellular length meet chirp change rule.
Figure 15 show chirp non-linear photon crystal prepared by method based on above-described embodiment in light microscope
Under surface topography map.Lines in figure are the line of demarcation under light microscope between adjacent positive and negative farmland.Figure 16 shows Figure 15's
The partial enlarged drawing of the surface topography of chirp non-linear photon crystal, wherein l+And l-Represent positive farmland and negative farmland in light propagation respectively
Length on direction.
Finally it should be noted that above example is only describing technical scheme rather than to this technology method
Limited, the present invention can above extend to other modifications, change, application and embodiment, and it is taken as that institute in application
There are such modification, change, application, embodiment all in the range of the spirit or teaching of the present invention.
Claims (10)
1. a kind of device for producing the visible super continuous laser near infrared band wideband adjustable, including pump light source and non-thread
Property laser crystal, it is characterised in that the pump light source is near-infrared femtosecond pulse light source；
The non-linear laser crystal includes a series of cellular, a series of length of the cellulars on optical propagation direction along
Optical propagation direction changes and changed according to continuous chirp.
2. the device according to claim 1 for producing the visible super continuous laser near infrared band wideband adjustable, its
It is characterised by, in the non-linear laser crystal, according to it is determined that each length of the cellular in a z-direction, wherein z are represented
The position coordinates on z directions corresponding to some cellular, z directions are the optical propagation direction, wherein being the femtosecond pulse
The polarization cycle required for frequency multiplication process corresponding to the centre wavelength of laser, it is chirp degree.
3. the device according to claim 2 for producing the visible super continuous laser near infrared band wideband adjustable, its
It is characterised by, the position coordinates corresponding to described cellular on z directions is the coordinate of the section start of the cellular.
4. the device according to claim 2 for producing the visible super continuous laser near infrared band wideband adjustable, its
It is characterised by, the polarization cycle, chirp degree, non-linear laser crystal length L combinations of values make the non-linear laser crystal
The reciprocal lattice vector of body is rendered as being distributed in several reciprocal lattice vector bands of diverse location.
5. the device according to claim 4 for producing the visible super continuous laser to near-infrared wideband adjustable, its feature
It is, the non-linear frequency that the super continuous laser in the broadband that several described reciprocal lattice vector bands correspond respectively to different-waveband participates in turns
Change process, and the non-linear frequency that the super continuous laser in broadband that each reciprocal lattice vector band effectively compensates for that there is continuous frequency spectrum to be distributed participates in
Rate transfer process.
6. the device according to claim 4 for producing the visible super continuous laser to near-infrared wideband adjustable, its feature
It is, secondary and triple-frequency harmonics the non-linear frequency that several described reciprocal lattice vector bands correspond respectively to pumping optical band turns
Change, effective phase compensation is provided for these nonlinear frequency conversions, and so that after secondary and triple-frequency harmonics band combination
Whole 400-900nm wave bands can be covered.
7. the device according to claim 1 for producing the visible super continuous laser near infrared band wideband adjustable, its
It is characterised by, the non-linear laser crystal is made using ferroelectric crystal materials, and the ferroelectric crystal materials are lithium columbate crystal
Material, magnesium-doped lithium niobate crystal or lithium tantalate material.
8. a kind of preparation method of non-linear laser crystal, it is characterised in that comprise the following steps：
1) mask plate with specific pattern is prepared, the pattern on the mask plate corresponds to a system of the non-linear laser crystal
Row cellular；A series of length on optical propagation direction of cellulars change along optical propagation direction according to continuous chirp and
Change；
2) in the surface spin coating photoresist of non-linear laser crystal, the pattern of mask plate is shifted and solidified on a photoresist；
3) non-linear laser crystal two sides is contacted with conducting medium respectively, then added by conducting medium in crystal upper and lower surface
The upper electric field more than crystal coercive field so that the region for not having photoresist on the non-linear laser crystal by electric current and can make
Polarised direction is obtained to reverse, and the region for remaining with photoresist remains in that original polarised direction.
9. preparation method according to claim 8, it is characterised in that the step 1) also includes：Attempt different polarization
Cycle, the combinations of values of chirp degree, according to formula, it is determined that the polarization cycle sequence of the cellular corresponding to various parameters combinations of values
Row, the reciprocal lattice vector band combination corresponding to these cellular polarization cycle sequences is then simulated, and then simulate swashing for final output
The wave band of light simultaneously preferably goes out parameter values combination, and combining corresponding cellular polarization cycle sequence according to the parameter values determines to cover
Pattern in film version.
10. preparation method according to claim 9, it is characterised in that the step 1) also includes：Analyze every kind of reciprocal lattice vector
Phase compensation with the provided non-linear process of combination, and then the wave band of the laser of final output is simulated, if simulated
The wave band of the laser of the final output gone out it is continuous and can cover it is visible near infrared band, then judge corresponding to parameter values group
Conjunction meets the requirements, and the cellular polarization cycle sequence according to corresponding to combining the parameter values determines the pattern on mask plate.
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| CN111129932A (en) * | 2019-12-12 | 2020-05-08 | 广东晶启激光科技有限公司 | Device for generating broadband supercontinuum laser and manufacturing method of crystal in device |
| CN111384654A (en) * | 2020-03-17 | 2020-07-07 | 中国科学院福建物质结构研究所 | Super-continuum spectrum laser light source |
| CN113820901A (en) * | 2021-08-26 | 2021-12-21 | 华南理工大学 | On-chip integrated frequency doubling device and preparation method thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106848809A (en) * | 2017-03-06 | 2017-06-13 | 李志远 | A kind of generation is visible to infrared band pole broadband, the device of super continuous laser |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106848809A (en) * | 2017-03-06 | 2017-06-13 | 李志远 | A kind of generation is visible to infrared band pole broadband, the device of super continuous laser |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111129932A (en) * | 2019-12-12 | 2020-05-08 | 广东晶启激光科技有限公司 | Device for generating broadband supercontinuum laser and manufacturing method of crystal in device |
| CN111384654A (en) * | 2020-03-17 | 2020-07-07 | 中国科学院福建物质结构研究所 | Super-continuum spectrum laser light source |
| CN111384654B (en) * | 2020-03-17 | 2021-12-14 | 中国科学院福建物质结构研究所 | Super-continuum spectrum laser light source |
| CN113820901A (en) * | 2021-08-26 | 2021-12-21 | 华南理工大学 | On-chip integrated frequency doubling device and preparation method thereof |
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