WO2018205441A1 - 一种宽带光参量啁啾脉冲放大器 - Google Patents

一种宽带光参量啁啾脉冲放大器 Download PDF

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Publication number
WO2018205441A1
WO2018205441A1 PCT/CN2017/097583 CN2017097583W WO2018205441A1 WO 2018205441 A1 WO2018205441 A1 WO 2018205441A1 CN 2017097583 W CN2017097583 W CN 2017097583W WO 2018205441 A1 WO2018205441 A1 WO 2018205441A1
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Prior art keywords
chirped
pulsed laser
optical parametric
laser
light
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English (en)
French (fr)
Inventor
钟亥哲
李瑛�
梁宇海
杨建龙
王世伟
范滇元
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Shenzhen University
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Shenzhen University
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    • 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
    • G02F1/39—Non-linear optics for parametric generation or amplification of light, infrared or ultraviolet waves
    • 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
    • H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
    • H01S3/0057—Temporal shaping, e.g. pulse compression, frequency chirping
    • 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
    • G02F1/39—Non-linear optics for parametric generation or amplification of light, infrared or ultraviolet waves
    • G02F1/392—Parametric amplification

Definitions

  • the invention belongs to the field of laser technology, and in particular relates to a broadband optical parametric chirped pulse amplifier.
  • OPCPA Optical Parametric Chirped-Pulse Amplification
  • the basic principle of OPCPA is to broaden the low-energy femtosecond ultrashort pulse laser into picosecond or nanosecond chirped pulses (the width of the broadened pulse width is equivalent to the pumping light), and then use the narrow-band high-energy pulsed laser as the pumping light.
  • the optical parametric amplification of the ultrashort pulse laser is performed, and finally the amplified chirped pulse signal is recompressed to the femtosecond level by a raster compressor at the output end.
  • all the parameters are subject to the return of energy.
  • the energy will flow back to the pump light by the pulsed laser and idler light.
  • the complex space-time pulse shaping technology is used to make the energy distribution of the pulsed laser and pump light more. Uniform, can achieve energy conversion efficiency of up to ⁇ 65%.
  • the idler light can be continuously absorbed by the crystal, and the backflow of the pulsed laser energy can be effectively suppressed.
  • the space-time shaping technology is used to amplify the pulsed laser synchronous optical parameters in different time and space regions. Although sufficient conversion efficiency can be obtained before the reflow occurs, the implementation of this method is more difficult, and more importantly, the pump light is more important. Even the space-time waveform of the pulsed laser has a large limitation; while the nonlinear material itself absorbs the specific laser wavelength, the technical solution for suppressing the pulsed laser energy reflow is not suitable for the easily absorbed laser wavelength (for example, 3 -5 The ⁇ m mid-infrared laser), and the thermal effects of absorption also affect the optical parametric chirped pulse amplifier.
  • phase matching bandwidth is one of the determinants of the optical parametric ⁇ pulse amplifier gain bandwidth.
  • the highest peak power output is one of the most important parameters for evaluating the performance of an optical parametric pulse amplifier.
  • the peak power of a pulsed laser is determined by the pulse energy and the pulse width. Under certain pump light energy and ultrashort pulse laser injection conditions, the conversion efficiency of pump light energy determines the output energy of ultrashort pulse laser, while the gain matching bandwidth of optical parametric amplification is the measurement of the shortest pulse laser output. Key indicators.
  • the maximum peak power output of the existing optical parametric chirped pulse amplifier is greatly affected, thereby reducing the performance of the optical parametric chirped pulse amplifier.
  • the invention provides a broadband optical parametric chirped pulse amplifier, which aims to simultaneously solve the energy reflow problem and the narrowing of the gain bandwidth in the existing optical parametric chirped pulse amplifier, realize synchronous optimization of conversion efficiency and gain bandwidth, and improve light.
  • Parametric ⁇ pulse amplifier performance aims to simultaneously solve the energy reflow problem and the narrowing of the gain bandwidth in the existing optical parametric chirped pulse amplifier, realize synchronous optimization of conversion efficiency and gain bandwidth, and improve light.
  • the present invention provides a broadband optical parametric chirped pulse amplifier, the broadband optical parametric chirped pulse amplifier comprising:
  • a pulsed laser stretcher for widening the incident ultrashort pulse laser such that the pulse width of the incoming chirped laser is the same as the pulse width of the incident pump light, and the chirped laser enters the optical coupling mirror;
  • the optical coupling mirror is configured to spatially couple the chirped pulsed laser light to the incident pumping light and enter the periodically polarized crystal together;
  • the periodically polarized crystal is configured to amplify a chirped pulsed laser based on incident pump light while generating idler light; and, the idler light, the chirped pulsed laser, and the pump Puguang performs separation to suppress the energy return of the broadband optical parametric pulse amplifier into saturation amplification; and, while suppressing energy reflow, realize wide-band optical parametric amplification of the chirped pulse laser;
  • the chirped pulsed laser enters the beam splitter together with the residual pump light;
  • the beam splitter is configured to separate the amplified chirped pulsed laser from the residual pumping light to ensure that only the amplified chirped pulsed laser enters the pulsed laser compressor;
  • the pulsed laser compressor is configured to compress a pulse width of the amplified chirped pulsed laser to obtain an ultrashort pulsed laser of high peak power.
  • the broadband optical parametric chirped pulse amplifier further includes an expansion/contraction beam system
  • the expansion/contraction beam system is disposed between the optical coupling mirror and the periodically polarized crystal for changing a spot of the chirped pulsed laser and the pumping light emitted by the optical coupling mirror
  • the aperture; the chirped pulsed laser adjusted by the aperture aperture enters the periodically polarized crystal together with the pumping light.
  • the periodically polarized crystal includes a first nonlinear region, a linear region, and a second nonlinear region that are sequentially connected; wherein the first nonlinear region and the second nonlinear region both have periodicity Domain inversion structure
  • An angle between a periodic domain inversion direction of the first nonlinear region and the chirped pulse laser transmission direction is ⁇ , and a periodic domain inversion direction of the second nonlinear region is opposite to the chirped pulsed laser
  • the angle of the transmission direction is - ⁇ such that the domain structure of the first non-linear region and the domain structure of the second non-linear region are axisymmetric along the chirped pulse laser transmission direction;
  • the first non-linear region is configured to cause the generated first idler light to move away from one side of the chirped pulsed laser and the pumping light
  • the second non-linear region is configured to cause the generated second idler light to be The chirped pulsed laser and the other side of the pump light are separated.
  • an angle ⁇ represents an angle between the idler light and a direction in which the chirped pulsed laser and the pump light are transmitted;
  • the periodic domain inversion structure of the periodically polarized crystal has the ability to make the kp, ks, ki, and kg four-way wave vectors form a wave-vector quadrilateral, wherein the ks represents the chirped laser light a wave vector, the kp represents a wave vector of the pump light, the ki represents a wave vector of the idler light, and the kg represents an inverted vector of the periodically polarized crystal, the ks and the Said kp collinear.
  • the broadband optical parametric chirped pulse amplifier further includes a narrowband picosecond laser
  • the narrowband picosecond laser for outputting pump light
  • the pump light output by the narrow-band picosecond laser is synchronized with the pulsed laser light obtained after the broadening.
  • the pump light and the chirped pulsed laser enter the periodically polarized crystal in a collinear normal incidence manner.
  • the invention has the following advantages:
  • the present invention provides a broadband optical parametric chirped pulse amplifier comprising a narrowband picosecond laser, a pulsed laser stretcher, an optical coupling mirror, a spread/contraction system, a periodically polarized crystal, and a spectroscopic Mirror and pulsed laser compressor.
  • the periodically polarized crystal having a periodic domain inversion structure is used for performing wide-bandwidth optical parametric amplification of the chirped pulsed laser based on the incident pump light, and simultaneously generating idler light; and the idler light, Separating from the chirped pulsed laser and the pumping light to suppress the energy return of the broadband optical parametric chirped pulse amplifier after saturation amplification; and based on suppressing energy reflow, the periodically polarized crystal is further Supports wide bandwidth phase matching. Since the broadband optical parametric chirped pulse amplifier not only suppresses the return of the signal light energy, but also has an extremely wide gain bandwidth, which is greatly improved by the simultaneous optimization of the pulse energy (conversion efficiency) and the pulse width (gain bandwidth).
  • the wideband optical parametric chirped pulse amplifier delivers the highest peak power and improves the performance of the optical parametric chirped amplifier.
  • the aperture of the pulsed laser and the pumping light in the periodically polarized crystal can be adjusted, and the gain of the optical parametric chirped pulse amplifier can be easily adjusted.
  • Bandwidth the smaller the aperture of the pulsed laser and the pump light, the wider the gain bandwidth.
  • the dual-optical parametric chirped pulse amplifier has a higher output peak power by the dual optimization of the gain bandwidth by the periodically polarized crystal and the expansion/contraction beam system.
  • FIG. 1 is a schematic diagram of a broadband optical parametric chirped pulse amplifier according to an embodiment of the present invention
  • FIG. 2 is a schematic diagram of a periodically polarized crystal provided by an embodiment of the present invention.
  • FIG. 3 is a top view of a periodically polarized crystal according to an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of a gain bandwidth of an optical parametric chirped pulse amplifier with different signal light/pump light spot diameters according to an embodiment of the present invention
  • FIG. 5 is a schematic diagram of “space-spectrum” of 800 nm signal light amplified by an optical parametric chirped pulse amplifier according to an embodiment of the present invention.
  • the present invention provides a broadband optical parametric chirped pulse amplifier comprising a pulsed laser stretcher 10, an optical coupling mirror 20, and a periodically polarized crystal having a periodic domain inversion structure. 40, beam splitter 50 and pulsed laser compressor 60.
  • Pulsed laser stretcher 10 for widening the incident ultrashort pulse laser (generally the ultrashort pulse laser after broadening) It is called a chirped pulse laser so that the pulse width of the chirped pulsed laser is the same as the pulse width of the incident pumping light, and the chirped pulsed laser enters the optical coupling mirror 20.
  • An optical coupling mirror 20 for spatially coupling the chirped pulsed laser light to the incident pumping light and entering the periodically polarized crystal together 40.
  • a beam splitter 50 for separating the amplified chirped laser light emitted from the periodically polarized crystal 40 and the residual pump light to Make sure that only the amplified chirped pulsed laser enters the pulsed laser compressor 60.
  • Pulsed laser compressor 60 for compressing amplified helium pulsed laser The pulse width is recompressed to the original pulse width before the pulsed laser stretcher 10 is broadened to obtain an ultrashort pulse laser with high peak power.
  • the present invention provides a broadband optical parametric chirped pulse amplifier comprising a narrowband picosecond laser 70, a pulsed laser stretcher 10, an optical coupling mirror 20, an extension / A reduced beam system 30, a periodically polarized crystal 40 having a periodic domain inversion structure, a beam splitter 50, and a pulsed laser compressor 60.
  • a pulsed laser stretcher 10 for widening the incident ultrashort pulse laser ⁇ s to make the ultrashort pulse laser after broadening (The ultrashort pulse laser after broadening is generally referred to as a chirped pulse laser.)
  • the pulse width of ⁇ s is the same as the pulse width of the incident pump light ⁇ p, and the chirped pulsed laser ⁇ s enters the optical coupling mirror 20 .
  • the pump light ⁇ p output from the narrow-band picosecond laser 70 is synchronized with the pulsed laser ⁇ s time obtained by broadening the pulsed laser stretcher 10.
  • Optical coupling mirror 20 for ⁇ pulsed laser ⁇ s and incident pump light ⁇ p Space coupling and entering the periodically polarized crystal 40 together. It should be noted that the pump light ⁇ p and the ⁇ pulse laser ⁇ s emitted from the optical coupling mirror 20 enter the expansion in a collinear normal incidence manner. Reduced beam system 30.
  • An expansion/contraction system 30 disposed between the optical coupling mirror 20 and the periodically polarized crystal 40 for changing the slave optical coupling mirror 20
  • the pupil pulse laser ⁇ s and the pump light ⁇ p are spotted, and the pupil pulse laser ⁇ s adjusted by the spot diameter enters the periodically polarized crystal 40 together with the pump light ⁇ p.
  • the aperture of the chirped laser ⁇ s and the pumping light ⁇ p can be changed to adjust the chirped laser ⁇ s and the pumping light ⁇ p
  • the aperture aperture in the periodically polarized crystal 40 is used to achieve dynamic regulation of the gain bandwidth of the broadband optical parametric chirped pulse amplifier.
  • the pulsed laser ⁇ s and the pump light ⁇ p The smaller the aperture of the spot, the wider the gain bandwidth of the optical parametric chirped amplifier. Because the aperture of the chirped pulsed laser ⁇ s and the pumping light ⁇ p is smaller, correspondingly, the periodically-polarized crystal 40 has idler light ⁇ i The faster the space is separated from the pulsed laser ⁇ s and the pump light ⁇ p, the smaller the influence of the idler light ⁇ i on the chirped pulsed laser ⁇ s and the pumping light ⁇ p.
  • the broadband optical parametric chirped amplifier is less sensitive to phase mismatch and has a wider gain bandwidth.
  • Dynamically controlling the gain bandwidth of the broadband optical parametric chirped pulse amplifier can be achieved by the aperture of the spot polarization crystal.
  • only one set of expansion/contraction system is provided. It is used to change the aperture size of the pulsed laser ⁇ s and the pump light ⁇ p in equal proportions.
  • Periodically polarized crystal 40 for incident pulsed laser light ⁇ p Amplify and generate idler light ⁇ i at the same time; and, idle frequency light ⁇ i, ⁇ pulse laser ⁇ s and pump light ⁇ p Separation is performed to suppress the broadband return of the broadband optical parametric pulse amplifier into saturation amplification; and, while suppressing energy reflow, a wide-bandwidth optical parametric amplification of the chirped pulsed laser ⁇ s is achieved.
  • zoomed in The chirped pulsed laser ⁇ s' enters the beam splitter along with the residual pump light ⁇ p'.
  • the periodically polarized crystal 40 The first nonlinear region, the linear region and the second nonlinear region are connected in sequence; wherein the first nonlinear region and the second nonlinear region both have a periodic domain inversion structure.
  • the angle between the periodic domain reversal direction of the first nonlinear region and the ⁇ pulse laser transmission direction is ⁇
  • the angle between the periodic domain reversal direction of the second nonlinear region and the ⁇ pulsed laser transmission direction is - ⁇ So that the domain structure of the first nonlinear region and the domain structure of the second nonlinear region are axisymmetric along the chirped pulse laser transmission direction.
  • the first non-linear region is used to generate the generated first idler light ⁇ i1 Moving away from one side of the pulsed laser and the pump light
  • the second non-linear region is used to generate the generated second idler light ⁇ i2 Walk away from the other side of the pulsed laser and pump light.
  • the linear region has no periodic domain inversion structure and is only used to separate idler light; the length of the linear region needs to be larger than the idler light transmitted by the non-collinear line, and the transmission length required to completely separate from the pulsed laser and the pumping light ensures Only the helium pulsed laser and pump light enter the second non-linear region.
  • Angle ⁇ represents the angle between the idler light and the direction in which the pulsed laser and the pump light are transmitted, that is, the angle between ki and ks/kp.
  • the first idler light ⁇ i1 due to the periodic domain inversion structure of the first nonlinear region It will be transmitted in a direction deviating from the ⁇ pulse laser/pump light ⁇ angle; due to the periodic domain inversion structure of the second nonlinear region, the second idler light ⁇ i2 will deviate from the ⁇ pulse laser/pump light - ⁇ The direction of the corner is transmitted.
  • the periodic domain inversion structure of the periodically polarized crystal 40 has kp , ks , ki , and kg
  • the ability of the four-way wave vector to form a wave-vector quadrilateral is intended to meet the requirements of phase matching.
  • ks represents the wave vector of the chirped pulsed laser
  • kp represents the wave vector of the pumping light
  • ki Indicates the wave vector of the idler light
  • kg represents the inverted vector of the periodically polarized crystal
  • ks is collinear with kp.
  • v signal represents the group velocity of the chirped laser in the periodically polarized crystal 40
  • v idler represents the group velocity of the idler light in the periodically polarized crystal 40
  • v signal v idler *cos( ⁇ ) .
  • the periodically polarized crystal 40 The domain inversion structure not only satisfies the requirements of phase matching, but also enables the generated idler light to continuously move away from the chirped pulsed laser and the pumping light, thereby achieving the purpose of suppressing energy reflow and improving energy conversion efficiency;
  • the angle will be ⁇ is set to the group velocity matching angle ⁇ , thereby achieving wide bandwidth phase matching and improving the gain bandwidth of the broadband optical parametric chirped amplifier.
  • the energy reflow problem and the narrowing of the gain bandwidth in the prior art are solved, and the synchronization efficiency and the gain bandwidth are optimized synchronously.
  • the maximum peak power output of the broadband optical parametric chirped amplifier is greatly improved, and the performance of the optical parametric chirped pulse amplifier is improved.
  • a beam splitter 50 for amplifying the chirped pulsed laser ⁇ s' and the residual pumping light ⁇ p' emitted by the periodically polarized crystal 40 Separation is performed to ensure that only the amplified erbium pulsed laser ⁇ s' is incident on the pulsed laser compressor 60.
  • Pulsed laser compressor 60 for compressing the amplified chirped pulsed laser ⁇ s' The pulse width is recompressed to the original pulse width before the pulsed laser stretcher 10 is broadened to obtain an ultrashort pulse laser with high peak power.
  • the broadband optical parametric chirped pulse amplifier provided by the second embodiment of the present invention.
  • the energy reflow problem and the narrowing of the gain bandwidth in the prior art are solved, and the conversion efficiency and the gain bandwidth are synchronously optimized, and the pulse energy (conversion efficiency) and the pulse width (gain bandwidth) are obtained.
  • the optimization of the key parameters determining the peak power of the ultrashort pulse laser significantly improves the maximum peak power output of the broadband optical parametric pulse amplifier and improves the performance of the optical parametric chirp.
  • by adjusting the expansion / The expansion/shrinkage multiple of the reduced beam system can also easily adjust the gain bandwidth of the optical parametric chirped pulse amplifier.
  • the broadband optical parametric chirped pulse amplifier has a higher output peak power by the dual optimization of the gain bandwidth by the periodically polarized crystal and the expansion/contraction beam system.
  • a broadband optical parametric chirped pulse amplifier comprising a narrowband picosecond laser, a pulsed laser stretcher, an optical coupling mirror, an extension / A reduced beam system, a periodically polarized crystal, a beam splitter, and a pulsed laser compressor.
  • the signal light is a 800 nm Ti:Sapphire pulsed laser.
  • the pulsed laser stretcher is an ⁇ ffner-type grating stretcher, and the pulsed laser compressor is Treacy type grating compressor.
  • the 800 nm Ti:Sapphire pulsed laser is broadened by an ⁇ ffner-type grating stretcher with a pulse width that is comparable to that of pump light.
  • Narrow-band picosecond laser is 532nm
  • the picosecond pulse laser which outputs a 532nm pulsed laser, is synchronized with the 800nm pulsed laser to be amplified, and is optically coupled to the 800nm pulsed laser.
  • Attenuation system and periodically polarized crystal pumping light with a picosecond pulsed laser with a wavelength of 532 nm, and amplifying a 800 nm chirped laser.
  • Expand / The beam-shrinking system can change the spot diameter of the signal light and the pumping light in the periodically polarized crystal in a proportional manner, thereby realizing the dynamic regulation of the gain bandwidth of the optical parametric chirped pulse amplifier.
  • the residual pump light is then separated from the amplified signal light by a beam splitter.
  • Amplified signal light The Treacy-type grating compressor compresses and finally obtains an ultrashort pulse laser with high peak power.
  • the periodically polarized crystal is a periodically polarized crystal having a periodic domain inversion structure as shown in FIG. 2, which can realize phase matching of a wide bandwidth and suppress the reflow of energy.
  • the polarization period ⁇ and the angle ⁇ of the periodically polarized crystal are determined by the mapping relationship between the angle ⁇ , the angle ⁇ , and the polarization period ⁇ .
  • the angle ⁇ is equal to 15.4 degrees; first, ⁇ is determined by ⁇ ; then in ⁇ and ⁇ In the determined periodic polarization crystal, the idler light naturally deviates from the ⁇ pulse laser and the pump light ⁇ angle.
  • the periodically polarized crystal is a 5% MgO doped periodically poled lithium niobate crystal that satisfies the 0-type alignment ( MgO: PPLN).
  • the operating temperature is set at 24.5 degrees Celsius. As shown in Figure 3, at 800nm signal light, 532nm pump light and corresponding 1588nm Under idle frequency conditions, the angle ⁇ between the idler light and the signal light/pump light transmission direction should be equal to 15.4 degrees.
  • the polarization period of the periodically polarized crystal that is, the domain length ⁇
  • the angle ⁇ between the direction of periodic domain inversion and the direction of laser light transmission is 63 degrees.
  • the total length of the non-linear region of the 5% MgO:PPLN crystal is 20 mm, wherein the first nonlinear region and the second nonlinear region are each 10 mm.
  • the gain bandwidth of the wideband optical parametric chirped pulse amplifier with different signal light/pump light spot diameters provided by the present invention is shown.
  • the gain bandwidth of a conventional optical parametric chirped pulse amplifier based on collinear phase matching is also shown.
  • the present invention can significantly increase the gain bandwidth of the optical parametric chirped pulse amplifier compared to collinear phase matching.
  • the expansion/contraction system can be used to easily and proportionally change the aperture of the signal light and the pumping light in the periodically polarized crystal, thereby realizing the dynamic regulation of the gain bandwidth of the optical parametric chirped pulse amplifier.
  • the smaller the aperture size the wider the gain bandwidth of the optical parametric chirped pulse amplifier.
  • the corresponding gain bandwidth exceeds 100 nm.
  • Such a gain bandwidth can support the effective amplification of ultrashort pulse laser with a pulse width of 20fs or more.
  • the 'space-spectrum' plot of the amplified 800 nm signal light of the optical parametric chirped pulse amplifier provided by the present invention is shown.
  • the laser spectrum of the different radius regions of the 800 nm signal light is shown.
  • the initial pulse of the 800 nm signal light is 70 fs (1/e 2 high full width)
  • the pulse width is extended to 70 ps by the ⁇ ffner-type grating stretcher, correspondingly, the pulse width of the 532 nm pump light is 100 ps.
  • the spot diameter of the 800 nm signal light and the 532 nm pump light is 1.1 mm.
  • the pump intensity in the PPLN crystal is 75 MW/cm 2 , and the signal light intensity is 1 ⁇ of the pump light intensity.
  • the 'space-spectrum' plot of the incident 800 nm signal light is also shown.
  • the amplified 800 nm signal light basically retains the initial spectral information, and there is no narrowing of the spectrum due to insufficient gain bandwidth. At the same time, its corresponding quantum conversion efficiency exceeds 70%. Thanks to the synchronous optimization of pulse energy (conversion efficiency) and pulse width (gain bandwidth), the highest peak power output of the optical parametric chirped pulse amplifier provided in this embodiment is based on the collinear phase under the same operating conditions. Matching conventional optical parametric ⁇ pulse amplifiers 5-10 times.
  • the broadband optical parametric chirped pulse amplifier provided by the third embodiment of the present invention can show from the simulation data that At the same time, the problem of energy reflow in the prior art and the narrowing of the gain bandwidth are solved, and the synchronization efficiency of the conversion efficiency and the gain bandwidth is realized, by the pulse energy (conversion efficiency) and the pulse width (gain bandwidth).
  • the optimization of the key parameters determining the peak power of the ultrashort pulse laser significantly improves the maximum peak power output of the broadband optical parametric pulse amplifier and improves the performance of the optical parametric chirp.

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Abstract

一种适用于激光技术领域的宽带光参量啁啾脉冲放大器，其包括窄带皮秒激光器（70）、脉冲激光展宽器（10）、光学耦合镜（20）、扩/缩束系统（30）、周期性极化晶体（40）、分光镜（50）以及脉冲激光压缩器（60）。其中，具有周期性畴反转结构的周期性极化晶体（40）用于将生成的闲频光、与啁啾脉冲激光/泵浦光进行分离，从而抑制宽带光参量啁啾脉冲放大器进入饱和放大后的能量回流；及实现宽带宽的光参量啁啾脉冲放大。宽带光参量啁啾脉冲放大器不但能抑制信号光能量的回流，还有极宽的增益带宽，得益于脉冲能量(转换效率)与脉冲宽度(增益带宽)的同步优化，大大提升了宽带光参量啁啾脉冲放大器的可输出最高峰值功率，提高了光参量啁啾脉冲放大器的性能。

Description

一种宽带光参量啁啾脉冲放大器 技术领域
本发明属于激光技术领域，尤其涉及一种宽带光参量啁啾脉冲放大器。
背景技术
光参量啁啾脉冲放大（Optical Parametric Chirped-Pulse Amplification， OPCPA）是提升超短脉冲激光能量的常用技术。OPCPA的基本原理是将低能量的飞秒超短脉冲激光展宽成皮秒或纳秒的啁啾脉冲（展宽后脉宽与泵浦光相当），再以窄带的高能量脉冲激光为泵浦光，对超短脉冲激光进行光参量放大，最后在输出端以光栅压缩器将放大后的啁啾脉冲信号重新压缩至飞秒量级。然而所有参量过程都会受制于能量的回流，回流是指当泵浦光强烈衰减，参量过程进入饱和放大的时候，能量会由啁啾脉冲激光和闲频光重新流向泵浦光。为了避免回流的发生，目前通常是借助各种优化设计，在倒流发生之前尽量实现较高的能量转换，使用复杂的空时脉冲整形技术，使啁啾脉冲激光、泵浦光的能量分布更为均匀，可以实现最高~65%的能量转换效率。此外，利用非线性材料自身对特定激光波长的吸收，使闲频光恰好能够被晶体持续吸收，可以有效抑制啁啾脉冲激光能量的回流。
但是，利用时空整形技术使不同时空区域的啁啾脉冲激光同步光参量放大，虽然可以在回流出现前得到足够的转换效率，但这种方法的实施难度较大，更重要的是对泵浦光，甚至啁啾脉冲激光的时空波形都有很大限制；而利用非线性材料自身对特定激光波长的吸收，抑制啁啾脉冲激光能量回流的技术方案并不适用于易吸收的激光波长（例如3-5 μm的中红外激光），而且，吸收带来的热效应还会对光参量啁啾脉冲放大器造成影响。
此外，相位匹配带宽是光参量啁啾脉冲放大器增益带宽的决定因素之一。相位匹配带宽是指：对宽光谱的飞秒激光而言，通常只有其中心波长能够满足相位匹配（Δk = 0），其余偏离中心波长的光谱成分均存在不同程度的相位失配（Δk ≠ 0），随着|Δk|的增加，光参量放大的转换效率迅速降低，一般将特定|Δk|范围内的超短脉冲激光的光谱带宽称为相位匹配带宽。超短脉冲激光的脉宽越短，所包含的光谱就越宽，对光参量啁啾脉冲放大器相位匹配带宽的要求也越高。可输出最高峰值功率是评价光参量啁啾脉冲放大器性能的最为重要的参数之一，脉冲激光的峰值功率由脉冲能量与脉冲宽度共同决定。在一定的泵浦光能量以及超短脉冲激光注入条件下，泵浦光能量的转换效率决定了超短脉冲激光的输出能量，而光参量放大的增益匹配带宽则是衡量其可输出最短脉冲激光的关键指标。
因此，由于受到能量回流以及增益带宽窄化的限制，现有的光参量啁啾脉冲放大器的可输出最高峰值功率受到极大影响，进而降低了光参量啁啾脉冲放大器的性能。
 技术问题
本发明提供了一种宽带光参量啁啾脉冲放大器，旨在同时解决现有光参量啁啾脉冲放大器中的能量回流问题以及增益带宽窄化问题，实现转换效率与增益带宽的同步优化，提高光参量啁啾脉冲放大器的性能。
技术解决方案
为解决上述技术问题，本发明提供了一种宽带光参量啁啾脉冲放大器，该宽带光参量啁啾脉冲放大器包括：
脉冲激光展宽器，用于对入射的超短脉冲激光进行啁啾展宽，以使得到的啁啾脉冲激光的脉宽与入射的泵浦光的脉宽相同，所述啁啾脉冲激光进入光学耦合镜；
所述光学耦合镜，用于使所述啁啾脉冲激光与所述入射的泵浦光空间耦合，并一同进入周期性极化晶体；
所述周期性极化晶体，用于基于入射的泵浦光对啁啾脉冲激光进行放大，同时生成闲频光；及，将所述闲频光、与所述啁啾脉冲激光和所述泵浦光进行分离，以抑制所述宽带光参量啁啾脉冲放大器进入饱和放大后的能量回流；及，在抑制能量回流的同时，实现对所述啁啾脉冲激光的宽带宽的光参量放大；放大的啁啾脉冲激光与残余的泵浦光一同进入分光镜；
所述分光镜，用于对放大的啁啾脉冲激光与残余的泵浦光进行分离，以确保仅有放大的啁啾脉冲激光进入脉冲激光压缩器；
所述脉冲激光压缩器，用于压缩所述放大的啁啾脉冲激光的脉冲宽度，得到高峰值功率的超短脉冲激光。
进一步地，所述宽带光参量啁啾脉冲放大器还包括扩/缩束系统；
所述扩/缩束系统，置于所述光学耦合镜与所述周期性极化晶体之间，用于改变所述光学耦合镜出射的所述啁啾脉冲激光与所述泵浦光的光斑口径；经光斑口径调整的所述啁啾脉冲激光与所述泵浦光一同进入所述周期性极化晶体。
进一步地，通过调整所述扩/缩束系统的扩/缩束倍数，改变所述啁啾脉冲激光与所述泵浦光的光斑口径，以实现对所述宽带光参量啁啾脉冲放大器的增益带宽的动态调控。
进一步地，所述周期性极化晶体包括依次相连的第一非线性区域、线性区域及第二非线性区域；其中，所述第一非线性区域与所述第二非线性区域均具有周期性畴反转结构；
所述第一非线性区域的周期性畴反转方向与所述啁啾脉冲激光传输方向的夹角为β，所述第二非线性区域的周期性畴反转方向与所述啁啾脉冲激光传输方向的夹角为-β，以使所述第一非线性区域的畴结构与所述第二非线性区域的畴结构沿所述啁啾脉冲激光传输方向呈轴对称；
所述第一非线性区域用于使生成的第一闲频光从所述啁啾脉冲激光和泵浦光的一侧走离，第二非线性区域用于使生成的第二闲频光从所述啁啾脉冲激光和泵浦光的另一侧走离。
进一步地，夹角α表示所述闲频光与所述啁啾脉冲激光和泵浦光传输方向之间的夹角；
所述夹角α等于满足宽带相位匹配所需的群速度匹配角Ω，以实现对所述啁啾脉冲激光的宽带宽的光参量放大；其中，Ω=arccos(vsignal/vidler)，vsignal表示所述啁啾脉冲激光在所述周期性极化晶体中的群速度，vidler表示所述闲频光在所述周期性极化晶体中的群速度，vsignal=vidler*cos(α)。
进一步地，所述周期性极化晶体的周期性畴反转结构具有使kp、ks、ki和kg四路波矢构成波矢四边形的能力，其中，所述ks表示所述啁啾脉冲激光的波矢、所述kp表示所述泵浦光的波矢、所述ki表示所述闲频光的波矢，所述kg表示所述周期性极化晶体的倒格矢，所述ks与所述kp共线。
进一步地，所述周期性极化晶体的极化周期Λ与所述夹角β，基于夹角α、夹角β、和kg之间的映射关系以及所述夹角α进行设定，以使所述周期性极化晶体满足相位匹配；其中，Λ=2π/kg，所述夹角α表示所述闲频光，与所述啁啾脉冲激光和泵浦光传输方向之间的夹角。
进一步地，所述宽带光参量啁啾脉冲放大器还包括窄带皮秒激光器；
所述窄带皮秒激光器，用于输出泵浦光；
所述窄带皮秒激光器输出的泵浦光与所述展宽后得到的啁啾脉冲激光时间同步。
进一步地，所述泵浦光与所述啁啾脉冲激光以共线正入射的方式，进入所述周期性极化晶体。
 有益效果
本发明与现有技术相比，有益效果在于：
本发明提供了一种宽带光参量啁啾脉冲放大器，该宽带光参量啁啾脉冲放大器包括窄带皮秒激光器、脉冲激光展宽器、光学耦合镜、扩/缩束系统、周期性极化晶体、分光镜以及脉冲激光压缩器。其中，具有周期性畴反转结构的周期性极化晶体用于基于入射的泵浦光对啁啾脉冲激光进行宽带宽的光参量放大，同时生成闲频光；并将所述闲频光、与所述啁啾脉冲激光和所述泵浦光进行分离，从而抑制所述宽带光参量啁啾脉冲放大器进入饱和放大后的能量回流；在抑制能量回流的基础上，该周期性极化晶体还支持宽带宽的相位匹配。由于该宽带光参量啁啾脉冲放大器不但抑制了信号光能量的回流，还具有极宽的增益带宽，得益于脉冲能量（转换效率）与脉冲宽度（增益带宽）的同步优化，大大提升了该宽带光参量啁啾脉冲放大器的可输出最高峰值功率，提高了光参量啁啾脉冲放大器的性能。同时，通过调整扩/缩束系统的扩/缩束倍数，从而调整啁啾脉冲激光与泵浦光于周期性极化晶体内的光斑口径，还可以简便地调控光参量啁啾脉冲放大器的增益带宽，啁啾脉冲激光与泵浦光的光斑口径越小，其增益带宽越宽。通过周期性极化晶体以及扩/缩束系统对增益带宽的双重优化，使得该宽带光参量啁啾脉冲放大器具有更高的可输出最高峰值功率。
 附图说明
图1是本发明实施例提供的宽带光参量啁啾脉冲放大器示意图；
图2是本发明实施例提供的周期性极化晶体示意图；
图3是本发明实施例提供的周期性极化晶体俯视图；
图4是本发明实施例提供的光参量啁啾脉冲放大器不同信号光/泵浦光光斑直径条件下的增益带宽示意图；
图5是本发明实施例提供的经光参量啁啾脉冲放大器放大后的800nm信号光的“空间-光谱”示意图。
 本发明的最佳实施方式
本发明的实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
作为本发明的第一个实施例，如图 1 所示，本发明提供了一种宽带光参量啁啾脉冲放大器，该宽带光参量啁啾脉冲放大器包括脉冲激光展宽器 10 、光学耦合镜 20 、具有周期性畴反转结构的周期性极化晶体 40 、分光镜 50 以及脉冲激光压缩器 60 。
脉冲激光展宽器 10 ，用于对入射的超短脉冲激光进行啁啾展宽 （一般将 展宽后的超短脉冲激光 称为啁啾脉冲激光） ，以使啁啾脉冲激光的脉宽与入射的泵浦光的脉宽相同，该啁啾脉冲激光 进入 光学耦合镜 20 。
光学耦合镜 20 ，用于使上述 啁啾脉冲激光 与入射的泵浦光空间耦合，并一同 进入 周期性极化晶体 40 。
周期性极化晶体 40 ，用于基于入射的泵浦光对入射的 啁啾脉冲激光 进行放大，同时生成闲频光；及，将闲频光、与 啁啾脉冲激光 和泵浦光进行分离，以抑制该宽带光参量啁啾脉冲放大器进入饱和放大后的能量回流；及，在抑制能量回流的同时，实现对该 啁啾脉冲激光 的宽带宽的光参量放大； 放大的 啁啾脉冲激光 与残余的泵浦光一同进入分光镜 50 。
分光镜 50 ，用于对经周期性极化晶体 40 出射的放大的 啁啾脉冲激光 与残余的泵浦光进行分离，以 确保仅有 放大的 啁啾脉冲激光 进入 脉冲激光压缩器 60 。
脉冲激光压缩器 60 ，用于压缩放大的 啁啾脉冲激光 的脉冲宽度，将其重新压缩至原来的经过脉冲激光展宽器 10 展宽之前的脉冲宽度，得到高峰值功率的超短脉冲激光。
综上所述，本发明第一个实施例所提供的宽带光参量啁啾脉冲放大器，其包含的周期性极化晶体 40 具有周期性畴反转结构，该周期性畴反转结构使得周期性极化晶体 40 能够抑制能量的回流，还有极宽的相位匹配带宽。因此，该光参量啁啾脉冲放大器不但抑制了能量的回流；在抑制能量回流的基础上，还有极宽的增益带宽， 得益于脉冲能量（转换效率）与脉冲宽度（增益带宽）的同步优化， 大大提升了该宽带光参量啁啾脉冲放大器的可输出最高峰值功率，提高了光参量啁啾脉冲放大器的性能。
作为本发明的第二个实施例，如图 1 所示，本发明提供了一种宽带光参量啁啾脉冲放大器，该宽带光参量啁啾脉冲放大器包括窄带皮秒激光器 70 、脉冲激光展宽器 10 、光学耦合镜 20 、扩 / 缩束系统 30 、具有周期性畴反转结构的周期性极化晶体 40 、分光镜 50 以及脉冲激光压缩器 60 。
窄带皮秒激光器 70 ，用于输出泵浦光 ωp 至光学耦合镜 20 。
脉冲激光展宽器 10 ，用于对入射的超短脉冲激光 ωs 进行啁啾展宽，以使展宽后的超短脉冲激光 （一般将 展宽后的超短脉冲激光 称为啁啾脉冲激光） ωs 的脉宽与入射的泵浦光 ωp 的脉宽相同，该 啁啾脉冲激光 ωs 进入光学耦合镜 20 。需要说明的是，窄带皮秒激光器 70 输出的泵浦光 ωp 与经脉冲激光展宽器 10 展宽后得到的 啁啾脉冲激光 ωs 时间同步。
光学耦合镜 20 ，用于使 啁啾脉冲激光 ωs 与入射的泵浦光 ωp 空间耦合，并一同进入周期性极化晶体 40 。需要说明的是，光学耦合镜 20 出射的泵浦光 ωp 和 啁啾脉冲激光 ωs 以共线正入射的方式，进入扩 / 缩束系统 30 。
扩 / 缩束系统 30 ，其置于光学耦合镜 20 和周期性极化晶体 40 之间，用于改变从光学耦合镜 20 出射的 啁啾脉冲激光 ωs 与泵浦光 ωp 的光斑口径， 经光斑口径调整的 啁啾脉冲激光 ωs 与泵浦光 ωp 一同进入周期性极化晶体 40 。 通过调整扩 / 缩束系统 30 的扩 / 缩束倍数，可以改变 啁啾脉冲激光 ωs 与泵浦光 ωp 的光斑口径， 从而调整 啁啾脉冲激光 ωs 与泵浦光 ωp 于周期性极化晶体 40 内的光斑口径，以实现对所述宽带光参量啁啾脉冲放大器的增益带宽的动态调控。 在其余条件不变的前提下， 啁啾脉冲激光 ωs 与泵浦光 ωp 的光斑口径越小，所述光参量啁啾脉冲放大器的增益带宽越宽。因为啁啾脉冲激光 ωs 与泵浦光 ωp 的光斑口径越小，相应的，周期性极化晶体 40 内闲频光 ωi ，与 啁啾脉冲激光 ωs 和泵浦光 ωp 的空间走离的速度越快， 闲频光 ωi 对 啁啾脉冲激光 ωs 和泵浦光 ωp 的影响越小， 该宽带光参量啁啾脉冲放大器对相位失配越不敏感，其增益带宽也就越宽。 通过调整 啁啾脉冲激光 ωs 与泵浦光 ωp 于所述周期性极化晶体内的光斑口径，可实现对所述宽带光参量啁啾脉冲放大器的增益带宽的动态调控。 在本实施例中，仅设置了一套扩 / 缩束系统 30 ，用于等比例的改变啁啾脉冲激光 ωs 与泵浦光 ωp 的光斑口径大小。
周期性极化晶体 40 ，用于基于入射的泵浦光 ωp 对入射的啁啾脉冲激光 ωs 进行放大，同时生成闲频光 ωi ；及，将闲频光 ωi 、与啁啾脉冲激光 ωs 和泵浦光 ωp 进行分离，以抑制该宽带光参量啁啾脉冲放大器进入饱和放大后的能量回流；及，在抑制能量回流的同时，实现对该啁啾脉冲激光 ωs 的宽带宽的光参量放大。 放大的 啁啾脉冲激光 ωs' 与残余的泵浦光 ωp' 一同进入分光镜。
如图 2 所示，该周期性极化晶体 40 包括依次相连的第一非线性区域、线性区域及第二非线性区域；其中，第一非线性区域与第二非线性区域均具有周期性畴反转结构。第一非线性区域的周期性畴反转方向与啁啾脉冲激光传输方向的夹角为 β ，第二非线性区域的周期性畴反转方向与啁啾脉冲激光传输方向的夹角为-β ，以使第一非线性区域的畴结构与第二非线性区域的畴结构沿该啁啾脉冲激光传输方向呈轴对称。如图 3 所示，第一非线性区域用于使生成的第一闲频光 ωi1 从啁啾脉冲激光和泵浦光的一侧走离，第二非线性区域用于使生成的第二闲频光 ωi2 从啁啾脉冲激光和泵浦光的另一侧走离。线性区域没有周期性畴反转结构，仅用于分离闲频光；线性区域的长度需大于非共线传输的闲频光，与啁啾脉冲激光和泵浦光完全分离所需传输长度，确保仅有啁啾脉冲激光和泵浦光进入第二非线性区域。夹角 α 表示闲频光，与啁啾脉冲激光和泵浦光传输方向之间的夹角，即 ki 与 ks/kp 之间的夹角。由于第一非线性区域的周期性畴反转结构，第一闲频光 ωi1 会以偏离啁啾脉冲激光 / 泵浦光 α 角的方向传输；由于第二非线性区域的周期性畴反转结构，第二闲频光 ωi2 会以偏离啁啾脉冲激光 / 泵浦光 -α 角的方向传输。
周期性极化晶体 40 的周期性畴反转结构具有使 kp 、 ks 、 ki 和 kg 四路波矢构成波矢四边形的能力，其目的是为了满足相位匹配的要求。其中， ks 表示所述啁啾脉冲激光的波矢、 kp 表示所述泵浦光的波矢、 ki 表示所述闲频光的波矢， kg 表示所述周期性极化晶体的倒格矢， ks 与 kp 共线。且夹角 α 、夹角 β 、和 kg 之间一一对应，存在一定的映射关系，周期性极化晶体 40 的极化周期 Λ 或所述夹角 β ，基于夹角 α 、夹角 β 、和 kg 之间的映射关系以及夹角 α 进行设定，以使周期性极化晶体 40 实现相位匹配，其中， Λ=2π/kg 。
本实施例所提供的夹角 α 等于满足宽带相位匹配所需的群速度匹配角 Ω ，即 α= Ω=arccos(v signal/v idler) ，此时该周期性极化晶体 40 能够实现对啁啾脉冲激光的宽带宽的光参量放大。其中， Ω=arccos(v signal/v idler) ， v signal 表示啁啾脉冲激光在周期性极化晶体 40 中的群速度， v idler 表示闲频光在周期性极化晶体 40 中的群速度， v signal =v idler*cos(α) 。
需要说明的是，周期性极化晶体 40 的畴反转结构既满足相位匹配的要求，还能够使产生的闲频光从啁啾脉冲激光和泵浦光持续走离，从而达到抑制能量回流的目的，提高了能量的转换效率；在抑制能量回流的基础上，将夹角 α 设置成群速度匹配角 Ω ，从而实现了宽带宽的相位匹配，提高了该宽带光参量啁啾脉冲放大器的增益带宽， 同时解决了现有技术中的能量回流问题以及增益带宽窄化问题，实现转换效率与增益带宽的同步优化 ，大大提升了该宽带光参量啁啾脉冲放大器的可输出最高峰值功率，提高了该光参量啁啾脉冲放大器的性能。
分光镜 50 ，用于对经周期性极化晶体 40 出射的放大的啁啾脉冲激光 ωs' 与残余的泵浦光 ωp' 进行分离，以确保仅有的放大的啁啾脉冲激光 ωs' 入射至脉冲激光压缩器 60 。
脉冲激光压缩器 60 ，用于压缩放大的啁啾脉冲激光 ωs' 的脉冲宽度，将其重新压缩至原来的经过脉冲激光展宽器 10 展宽之前的脉冲宽度，得到高峰值功率的超短脉冲激光。
综上所述，本发明第二个实施例所提供的宽带光参量啁啾脉冲放大器， 同时解决了现有技术中的能量回流问题以及增益带宽窄化问题，实现转换效率与增益带宽的同步优化 ，通过对 脉冲能量（转换效率）与脉冲宽度（增益带宽） 这两个决定超短脉冲激光峰值功率的关键参数的优化，显著提升了该宽带光参量啁啾脉冲放大器的可输出最高峰值功率，提高了该光参量啁啾脉冲的性能。同时，通过调整扩 / 缩束系统的扩 / 缩束倍数，还可以简便地调控光参量啁啾脉冲放大器的增益带宽， 啁啾脉冲激光 ωs 与泵浦光 ωp 的光斑口径越小，其增益带宽越宽。 通过周期性极化晶体以及扩 / 缩束系统对增益带宽的双重优化，使得该宽带光参量啁啾脉冲放大器具有更高的可输出最高峰值功率。
作为本发明的第三个实施例，提供了一种宽带光参量啁啾脉冲放大器，其由窄带皮秒激光器，脉冲激光展宽器，光学耦合镜，扩 / 缩束系统，周期性极化晶体，分光镜以及脉冲激光压缩器构成。
信号光为 800nm 的钛宝石脉冲激光。脉冲激光展宽器为 Öffner 型光栅展宽器，脉冲激光压缩器为 Treacy 型光栅压缩器。 800nm 的钛宝石脉冲激光经 Öffner 型光栅展宽器展宽，其啁啾展宽后的脉冲宽度与泵浦光相当。窄带皮秒激光器为 532nm 皮秒脉冲激光器，其输出的 532nm 脉冲激光，与待放大的 800nm 的啁啾脉冲激光时间同步，经过光学耦合镜，与 800nm 的啁啾脉冲激光一同依次经过扩 / 缩束系统和周期性极化晶体，以波长为 532nm 的皮秒脉冲激光为泵浦光，对 800nm 的啁啾脉冲激光进行放大。扩 / 缩束系统可以等比例的改变信号光与泵浦光于周期性极化晶体的光斑口径，以此实现光参量啁啾脉冲放大器增益带宽的动态调控。再由分光镜，将残余的泵浦光从放大后的信号光中分离。放大后的信号光经 Treacy 型光栅压缩器压缩，最终得到高峰值功率的超短脉冲激光。
其中，周期性极化晶体为如图 2 所示的具有周期性畴反转结构的周期性极化晶体，可以实现宽带宽的相位匹配以及抑制能量的回流。闲频光与啁啾脉冲激光 / 泵浦光传输方向之间的夹角 α 等于群速度匹配角 Ω ， Ω=arccos(v signal/v idler) ，其中， v signal 、 v idler 分别表示啁啾脉冲激光与闲频光在周期性极化晶体中的群速度，即闲频光于啁啾脉冲激光传输方向上的群速度分量与信号光的群速度相等， v signal =v idler*cos(α) 。再由夹角 α ，夹角 β ，以及极化周期 Λ 之间的映射关系确定该周期性极化晶体的极化周期 Λ 与夹角 β 。
在本实施例中，夹角 α 等于 15.4 度；首先由 α 确定 β 跟 Λ ；然后在 β 和 Λ 确定的周期性极化晶体中，闲频光自然会偏离啁啾脉冲激光与泵浦光 α 角度走离。周期性极化晶体为满足 0 类准位相匹配的 5%MgO 掺杂周期性极化铌酸锂晶体（ MgO:PPLN ）。工作温度设定在 24.5 摄氏度 。如图 3 所示，在 800nm 信号光， 532nm 泵浦光以及对应的 1588nm 闲频光条件下，闲频光与信号光 / 泵浦光传输方向之间的夹角 α 应等于 15.4 度。对应的，为了满足 0 类准相位匹配，周期性极化晶体的极化周期，即畴长 Λ 为 2.5μm ，其周期性畴反转的方向与激光传输方向之间的夹角 β 为 63 度。
假定 800nm 的啁啾脉冲激光与 532nm 的泵浦光的光斑直径相同， 5%MgO:PPLN 晶体的非线性区域的总长度为 20mm ，其中第一非线性区域与第二非线性区域各 10mm 。如图 4 所示，图中给出了本发明所提供的宽带光参量啁啾脉冲放大器不同信号光 / 泵浦光光斑直径条件下的增益带宽。图中还同时给出了基于共线相位匹配的常规光参量啁啾脉冲放大器的增益带宽。由图中可见，相比于共线相位匹配，本发明可显著提升光参量啁啾脉冲放大器的增益带宽。而且，利用扩 / 缩束系统可简便的等比例改变信号光与泵浦光于周期性极化晶体的光斑口径，以此实现光参量啁啾脉冲放大器增益带宽的动态调控。一般的，光斑口径越小，光参量啁啾脉冲放大器的增益带宽越宽。以 1.1mm 的光斑直径（ 1/e2 高全宽）为例，其对应的增益带宽超过 100 nm ，这样的增益带宽可支持脉冲宽度大于等于 20fs 的超短脉冲激光的有效放大。
基于全维度（时间 - 空间）的仿真实验，如图 5 所示，图中给出了本发明所提供的光参量啁啾脉冲放大器的放大后的 800nm 信号光的 ' 空间 - 光谱 ' 图。图中给出了 800nm 信号光不同半径区域的激光光谱。具体的， 800nm 信号光的初始脉冲为 70fs （ 1/e2 高全宽），经 Öffner 型光栅展宽器，将其脉冲啁啾展宽至 70ps ，对应的， 532nm 泵浦光的脉冲宽度为 100ps 。 800nm 信号光与 532nm 泵浦光的光斑直径均为 1.1mm 。 5%MgO:PPLN 晶体中的泵浦光强为 75MW/cm2 ，信号光光强为泵浦光光强的 1‰ 。作为子图，图中还一同给出了入射的 800nm 信号光的 ' 空间 - 光谱 ' 图。由图中可见，放大后的 800nm 信号光基本保留了初始的光谱信息，没有出现因为增益带宽不足导致的光谱的窄化。与此同时，其对应的量子转换效率超过 70% 。得益于脉冲能量（转换效率）与脉冲宽度（增益带宽）的同步优化，在相同的工作条件下，本实施例所提供的光参量啁啾脉冲放大器的可输出最高峰值功率是基于共线相位匹配的常规光参量啁啾脉冲放大器的 5-10 倍。
综上所述，本发明第三个实施例所提供的宽带光参量啁啾脉冲放大器，从仿真数据可以表明，其 同时解决了现有技术中的能量回流问题以及增益带宽窄化问题，实现了转换效率与增益带宽的同步优化 ，通过对 脉冲能量（转换效率）与脉冲宽度（增益带宽） 这两个决定超短脉冲激光峰值功率的关键参数的优化，显著提升了该宽带光参量啁啾脉冲放大器的可输出最高峰值功率，提高了该光参量啁啾脉冲的性能。
以上所述仅为本发明的较佳实施例而已，并不用以限制发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (9)

  1. 一种宽带光参量啁啾脉冲放大器，其特征在于，所述宽带光参量啁啾脉冲放大器包括：
    脉冲激光展宽器，用于对入射的超短脉冲激光进行啁啾展宽，以使得到的啁啾脉冲激光的脉宽与入射的泵浦光的脉宽相同，所述啁啾脉冲激光进入光学耦合镜；
    所述光学耦合镜，用于使所述啁啾脉冲激光与所述入射的泵浦光空间耦合，并一同进入周期性极化晶体；
    所述周期性极化晶体，用于基于入射的泵浦光对啁啾脉冲激光进行放大，同时生成闲频光；及，将所述闲频光、与所述啁啾脉冲激光和所述泵浦光进行分离，以抑制所述宽带光参量啁啾脉冲放大器进入饱和放大后的能量回流；及，在抑制能量回流的同时，实现对所述啁啾脉冲激光的宽带宽的光参量放大；放大的啁啾脉冲激光与残余的泵浦光一同进入分光镜；
    所述分光镜，用于对放大的啁啾脉冲激光与残余的泵浦光进行分离，以确保仅有放大的啁啾脉冲激光进入脉冲激光压缩器；
    所述脉冲激光压缩器，用于压缩所述放大的啁啾脉冲激光的脉冲宽度，得到高峰值功率的超短脉冲激光。
  2. 如权利要求1所述的宽带光参量啁啾脉冲放大器，其特征在于，所述宽带光参量啁啾脉冲放大器还包括扩/缩束系统；
    所述扩/缩束系统，置于所述光学耦合镜与所述周期性极化晶体之间，用于改变所述光学耦合镜出射的所述啁啾脉冲激光与所述泵浦光的光斑口径；经光斑口径调整的所述啁啾脉冲激光与所述泵浦光一同进入所述周期性极化晶体。
  3. 如权利要求2所述的宽带光参量啁啾脉冲放大器，其特征在于，通过调整所述扩/缩束系统的扩/缩束倍数，改变所述啁啾脉冲激光与所述泵浦光的光斑口径，以实现对所述宽带光参量啁啾脉冲放大器的增益带宽的动态调控。
  4. 如权利要求1所述的宽带光参量啁啾脉冲放大器，其特征在于，所述周期性极化晶体包括依次相连的第一非线性区域、线性区域及第二非线性区域；其中，所述第一非线性区域与所述第二非线性区域均具有周期性畴反转结构；
    所述第一非线性区域的周期性畴反转方向与所述啁啾脉冲激光传输方向的夹角为β，所述第二非线性区域的周期性畴反转方向与所述啁啾脉冲激光传输方向的夹角为-β，以使所述第一非线性区域的畴结构与所述第二非线性区域的畴结构沿所述啁啾脉冲激光传输方向呈轴对称；
    所述第一非线性区域用于使生成的第一闲频光从所述啁啾脉冲激光和泵浦光的一侧走离，第二非线性区域用于使生成的第二闲频光从所述啁啾脉冲激光和泵浦光的另一侧走离。
  5. 如权利要求1所述的宽带光参量啁啾脉冲放大器，其特征在于：
    夹角α表示所述闲频光与所述啁啾脉冲激光和泵浦光传输方向之间的夹角；
    所述夹角α等于满足宽带相位匹配所需的群速度匹配角Ω，以实现对所述啁啾脉冲激光的宽带宽的光参量放大；其中，Ω=arccos(vsignal/vidler)，vsignal表示所述啁啾脉冲激光在所述周期性极化晶体中的群速度，vidler表示所述闲频光在所述周期性极化晶体中的群速度，vsignal=vidler*cos(α)。
  6. 如权利要求4所述的宽带光参量啁啾脉冲放大器，其特征在于，所述周期性极化晶体的周期性畴反转结构具有使kp、ks、ki和kg四路波矢构成波矢四边形的能力，其中，所述ks表示所述啁啾脉冲激光的波矢、所述kp表示所述泵浦光的波矢、所述ki表示所述闲频光的波矢，所述kg表示所述周期性极化晶体的倒格矢，所述ks与所述kp共线。
  7. 如权利要求6所述的宽带光参量啁啾脉冲放大器，其特征在于，所述周期性极化晶体的极化周期Λ与所述夹角β，基于夹角α、夹角β、和kg之间的映射关系以及所述夹角α进行设定，以使所述周期性极化晶体满足相位匹配；其中，Λ=2π/kg，所述夹角α表示所述闲频光，与所述啁啾脉冲激光和泵浦光传输方向之间的夹角。
  8. 如权利要求1所述的宽带光参量啁啾脉冲放大器，其特征在于，所述宽带光参量啁啾脉冲放大器还包括窄带皮秒激光器；
    所述窄带皮秒激光器，用于输出泵浦光；
    所述窄带皮秒激光器输出的泵浦光与所述展宽后得到的啁啾脉冲激光时间同步。
  9. 如权利要求1所述的宽带光参量啁啾脉冲放大器，其特征在于，所述泵浦光与所述啁啾脉冲激光以共线正入射的方式，进入所述周期性极化晶体。
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CN106911056B (zh) * 2017-05-08 2019-02-22 深圳大学 一种宽带光参量啁啾脉冲放大器
WO2019028831A1 (zh) * 2017-08-11 2019-02-14 深圳大学 一种双啁啾频谱光参量放大器及放大方法
CN108155554B (zh) * 2018-01-31 2019-08-16 深圳大学 一种光参量激光放大器制备方法及光参量激光放大器
CN108281877A (zh) * 2018-03-14 2018-07-13 成都师范学院 基于光谱角色散的啁啾激光脉冲频谱整形系统
CN109659804A (zh) * 2019-01-08 2019-04-19 中国科学院福建物质结构研究所 用于产生波峰可调的宽带橙光激光器
CN109616863B (zh) * 2019-01-15 2021-02-02 上海交通大学 通过闲频光倍频实现高效率非线性频率下转换的方法和装置
CN110336178B (zh) * 2019-08-06 2020-06-30 深圳大学 对温度变化不敏感的宽带光参量啁啾脉冲放大器
CN113189824B (zh) * 2021-04-21 2022-08-09 中国科学院上海光学精密机械研究所 一种基于双非线性光学过程的宽带光参量放大装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030112494A1 (en) * 2001-12-13 2003-06-19 The Regents Of The University Of California Hybrid chirped pulse amplification system
CN103217851A (zh) * 2013-03-19 2013-07-24 华中科技大学 共线光参量放大方法及装置
CN104300354A (zh) * 2014-10-29 2015-01-21 深圳大学 一种基于i类准位相匹配的光参量振荡激光器
CN106207718A (zh) * 2016-09-07 2016-12-07 深圳大学 一种针对中红外脉冲激光的光谱调控装置
CN106911056A (zh) * 2017-05-08 2017-06-30 深圳大学 一种宽带光参量啁啾脉冲放大器

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102768451B (zh) * 2012-07-31 2015-09-16 南京大学 具有偏振无关光参量放大特性的矢量光束放大与产生器件

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030112494A1 (en) * 2001-12-13 2003-06-19 The Regents Of The University Of California Hybrid chirped pulse amplification system
CN103217851A (zh) * 2013-03-19 2013-07-24 华中科技大学 共线光参量放大方法及装置
CN104300354A (zh) * 2014-10-29 2015-01-21 深圳大学 一种基于i类准位相匹配的光参量振荡激光器
CN106207718A (zh) * 2016-09-07 2016-12-07 深圳大学 一种针对中红外脉冲激光的光谱调控装置
CN106911056A (zh) * 2017-05-08 2017-06-30 深圳大学 一种宽带光参量啁啾脉冲放大器

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
LI, YING ET AL.: "Versatile Backconversion-inhibited Broadband Optical Parametric Amplification Based on an Idler-separated QPM Configuration", OPTICS LETTERS, vol. 42, no. 14, 15 July 2017 (2017-07-15), pages 2806 - 2809, XP055545187 *
YUAN, PENG ET AL.: "High-contrast Near-IR Short Pulses Generated by a Mid-IR Optical Parametric Chirped-pulse Amplifier with Frequency Doubling", OPTICS LETTERS, vol. 35, no. 11, 26 May 2010 (2010-05-26), pages 1879 - 1880, XP001554392 *

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