CN114784607A

Movatterモバイル変換

Info

Publication number: CN114784607A
Application number: CN202210363705.4A
Authority: CN
Inventors: 何洋; 陈飞; 于德洋; 张阔; 潘其坤; 孙俊杰; 陈毅
Original assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Current assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Priority date: 2022-04-08
Filing date: 2022-04-08
Publication date: 2022-07-22

Abstract

The invention relates to the technical field of laser, in particular to a tunable optical parametric oscillator, which comprises an optical fiber laser, a pump optical coupling device, a nonlinear crystal, a crystal temperature control furnace and a resonant cavity mirror, wherein the pump optical coupling device is connected with the nonlinear crystal; the fiber laser is used for outputting tunable pulse linear polarization pump laser; the pump light coupling device is used for isolating, beam-shrinking and polarization state adjustment of the tunable pulse linear polarization pump laser; the nonlinear crystal is used for generating signal light and idler frequency light; the crystal temperature control furnace is used for controlling the working temperature of the nonlinear crystal; the resonant cavity mirror is used for oscillating signal light; the tunable optical parametric oscillator can change the pumping wavelength by electrically controlling and changing the transmission wavelength of the tunable optical fiber filter in the seed optical fiber laser without changing the angle, the working temperature or the polarization period of a crystal, thereby realizing the large-range quick tuning of signal light and idler frequency light.

Description

Translated fromChinese

一种可调谐光参量振荡器A Tunable Optical Parametric Oscillator

技术领域technical field

本发明涉及激光技术领域，具体涉及一种可调谐光参量振荡器。The invention relates to the field of laser technology, in particular to a tunable optical parametric oscillator.

背景技术Background technique

光学参量振荡器(OPO)可将泵浦激光(频率为ωp)通过非线性晶体的二阶非线性效应转换为两个频率较低的信号光(频率为ωs)和闲频光(频率为ωi，且ωi＜ωs)，信号光和闲频光的频率之和与泵浦光频率相等，即ωs+ωi＝ωp。OPO是可调谐激光产生的重要方法之一，可在很宽的频率范围内实现调谐。The optical parametric oscillator (OPO) can convert the pump laser (frequency is ωp) into two lower frequency signal light (frequency is ωs) and idler light (frequency is ωi) through the second-order nonlinear effect of nonlinear crystal. , and ωi<ωs), the sum of the frequencies of the signal light and the idler light is equal to the frequency of the pump light, that is, ωs+ωi=ωp. OPO is one of the important methods for tunable laser generation, which can be tuned in a wide frequency range.

对于采用角度相位匹配的非线性晶体来说，通过旋转晶体的角度以满足不同波长信号光和闲频光的相位匹配条件，实现波长可调谐激光输出，但对旋转台的精度要求极高。For nonlinear crystals with angular phase matching, the wavelength tunable laser output can be achieved by rotating the angle of the crystal to meet the phase matching conditions of different wavelengths of signal light and idler light, but the precision of the rotating table is extremely high.

同时，对于采用准相位匹配的非线性晶体，其通常以固定周期对晶体进行周期极化以实现准相位匹配(例如周期极化铌酸锂(PPLN)、周期极化钽酸锂(PPLT)等)，当泵浦光波长一定时，信号光与闲频光的波长与晶体的极化周期相关，因此，基于准相位匹配晶体的OPO无法通过简单的旋转晶体角度实现波长调谐激光输出，其波长调谐方法通常包括以下几种方式：Meanwhile, for nonlinear crystals using quasi-phase matching, the crystals are usually periodically polarized with a fixed period to achieve quasi-phase matching (such as periodically polarized lithium niobate (PPLN), periodically polarized lithium tantalate (PPLT), etc. ), when the wavelength of the pump light is constant, the wavelengths of the signal light and the idler light are related to the polarization period of the crystal. Therefore, the OPO based on the quasi-phase matching crystal cannot realize the wavelength-tuning laser output by simply rotating the crystal angle. Tuning methods usually include the following ways:

调节晶体工作温度：当晶体温度改变时，晶体的折射率和极化周期会发生微小变化，从而对信号光和闲频光的波长进行调谐，但是该方法的缺点是波长调谐范围较小，且晶体工作温度改变需要时间，不易快速调谐波长；Adjusting the crystal working temperature: When the crystal temperature changes, the refractive index and polarization period of the crystal will change slightly, so as to tune the wavelength of the signal light and idler light, but the disadvantage of this method is that the wavelength tuning range is small, and It takes time to change the working temperature of the crystal, and it is not easy to quickly tune the wavelength;

采用多通道周期极化晶体：晶体上有多个通道，每个通道的极化周期不一样，通过位移台切换通道，可实现不同波长激光输出，但是该方法的缺点是无法对波长进行连续调谐，且对位移台的精度要求极高；Using multi-channel periodic polarization crystal: There are multiple channels on the crystal, and the polarization period of each channel is different. By switching the channel through the stage, the laser output of different wavelengths can be realized, but the disadvantage of this method is that the wavelength cannot be continuously tuned. , and the precision of the displacement stage is extremely high;

采用特殊结构的周期极化晶体：如图1和图2所示，采用新型的扇形周期或圆形端面周期极化晶体，通过横向移动晶体或旋转晶体可实现极化周期的连续调节，无需改变工作温度即可实现波长的连续调谐。但是对于扇形周期极化晶体，由于激光光斑通常有一定宽度，导致光斑内的极化周期不一致，不易实现窄线宽激光输出，对于圆形端面周期极化晶体，圆形端面对激光光束质量会产生影响，且上述两种晶体的移动对位移台或旋转台的精度要求极高，同时，特殊结构的晶体制作均较为复杂，成本较高。Periodically polarized crystal with special structure: As shown in Figure 1 and Figure 2, a new type of fan-shaped periodic polarized crystal or circular end face periodic polarized crystal is used, and the polarization period can be continuously adjusted by laterally moving the crystal or rotating the crystal, without changing the The wavelength can be continuously tuned at the operating temperature. However, for fan-shaped periodically polarized crystals, since the laser spot usually has a certain width, the polarization period in the spot is inconsistent, and it is difficult to achieve narrow linewidth laser output. will have an impact, and the movement of the above two crystals requires extremely high precision of the displacement stage or the rotary stage. At the same time, the production of crystals with special structures is relatively complicated and expensive.

发明内容SUMMARY OF THE INVENTION

本发明为解决上述问题，提供一种新型结构的可调谐光参量振荡器，无需改变晶体的角度、工作温度或极化周期，通过电控改变种子光纤激光器中可调谐光纤滤波器的透射波长，即可改变泵浦波长，实现对信号光和闲频光的大范围快速调谐。In order to solve the above problems, the present invention provides a tunable optical parametric oscillator with a novel structure, without changing the crystal angle, operating temperature or polarization period, and changing the transmission wavelength of the tunable fiber filter in the seed fiber laser by electronic control, The pump wavelength can be changed, and a wide range of fast tuning of signal light and idler light can be realized.

为实现上述目的，本发明采用以下具体技术方案：For achieving the above object, the present invention adopts following concrete technical scheme:

本发明提供一种可调谐光参量振荡器，所述可调谐光参量振荡器包括光纤激光器、泵浦光耦合装置、非线性晶体、晶体温控炉以及谐振腔镜；The invention provides a tunable optical parametric oscillator. The tunable optical parametric oscillator comprises a fiber laser, a pump optical coupling device, a nonlinear crystal, a crystal temperature-controlled furnace and a resonant cavity mirror;

所述光纤激光器用于输出可调谐脉冲线偏振泵浦激光；所述泵浦光耦合装置用于对所述可调谐脉冲线偏振泵浦激光进行隔离、缩束和偏振态调节；所述非线性晶体用于产生信号光和闲频光；所述晶体温控炉用于控制所述非线性晶体的工作温度；所述谐振腔镜用于所述信号光的振荡。The fiber laser is used to output a tunable pulse linearly polarized pump laser; the pump optical coupling device is used to isolate, narrow the beam and adjust the polarization state of the tunable pulse linearly polarized pump laser; the nonlinear The crystal is used to generate signal light and idler light; the crystal temperature-controlled furnace is used to control the working temperature of the nonlinear crystal; the resonant cavity mirror is used to oscillate the signal light.

优选的，所述光纤激光器包括种子光纤激光器、光纤预放大器以及光纤主放大器；所述种子光纤激光器用于产生第一线偏振激光，作为光纤预放大器的可调谐脉冲线偏振种子激光；所述光纤预放大器用于对所述第一线偏振激光进行功率预放大，产生第二线偏振激光；所述光纤主放大器用于对所述第二线偏振激光进行功率放大，产生可调谐脉冲线偏振泵浦激光。Preferably, the fiber laser includes a seed fiber laser, a fiber pre-amplifier and a fiber main amplifier; the seed fiber laser is used to generate a first linearly polarized laser as a tunable pulse linearly polarized seed laser of the fiber pre-amplifier; the fiber The pre-amplifier is used to pre-amplify the power of the first linearly polarized laser to generate a second linearly polarized laser; the optical fiber main amplifier is used to amplify the power of the second linearly polarized laser to generate a tunable pulse linearly polarized pump laser .

优选的，所述种子光纤激光器为环形腔结构；所述种子光纤激光器包括第一半导体激光泵浦源、第一合束器、第一保偏增益光纤、可调谐光纤滤波器、第一光纤隔离器、光纤耦合器以及光纤声光调制器；Preferably, the seed fiber laser has a ring cavity structure; the seed fiber laser includes a first semiconductor laser pump source, a first beam combiner, a first polarization-maintaining gain fiber, a tunable fiber filter, and a first fiber isolation devices, fiber couplers and fiber acousto-optic modulators;

所述第一半导体激光泵浦源用于为所述种子光纤激光器提供第一泵浦光；the first semiconductor laser pump source is used to provide the first pump light for the seed fiber laser;

所述第一合束器用于将所述第一泵浦光和未耦合输出的第一线偏振激光耦合至所述第一保偏增益光纤中；The first beam combiner is used for coupling the first pump light and the uncoupled output first linearly polarized laser into the first polarization-maintaining gain fiber;

所述第一保偏增益光纤用于将所述第一泵浦光的能量转化为第一线偏振激光的能量；The first polarization-maintaining gain fiber is used for converting the energy of the first pump light into the energy of the first linearly polarized laser light;

所述可调谐光纤滤波器用于调谐所述第一线偏振激光的波长；The tunable fiber filter is used for tuning the wavelength of the first linearly polarized laser light;

所述第一光纤隔离器用于控制所述第一线偏振激光的传输方向；The first fiber isolator is used to control the transmission direction of the first linearly polarized laser light;

所述光纤耦合器用于将部分所述第一线偏振激光耦合，输出作为种子激光；The optical fiber coupler is used for coupling part of the first linearly polarized laser light, and outputting it as a seed laser light;

所述光纤声光调制器用于对所述光纤激光进行调制，形成脉冲激光。The fiber acousto-optic modulator is used to modulate the fiber laser to form a pulsed laser.

优选的，所述光纤预放大器包括第二半导体激光泵浦源、第二合束器、第二保偏增益光纤以及第二光纤隔离器；Preferably, the fiber preamplifier includes a second semiconductor laser pump source, a second beam combiner, a second polarization-maintaining gain fiber, and a second fiber isolator;

所述第二半导体激光泵浦源用于为所述光纤预放大器提供第二泵浦光；the second semiconductor laser pump source is used to provide the second pump light for the fiber preamplifier;

所述第二合束器用于将所述第二泵浦光和光纤耦合器输出的第一线偏振激光耦合至所述第二保偏增益光纤中；The second beam combiner is used for coupling the second pump light and the first linearly polarized laser output from the fiber coupler into the second polarization-maintaining gain fiber;

所述第二保偏增益光纤用于将所述第二泵浦光的能量转化为第二线偏振激光的能量，对所述种子激光器输出的第一线偏振激光功率进行放大。The second polarization-maintaining gain fiber is used for converting the energy of the second pump light into the energy of the second linearly polarized laser, and amplifying the power of the first linearly polarized laser output by the seed laser.

优选的，所述第二半导体激光泵浦源的功率大于所述第一半导体激光泵浦源的功率。Preferably, the power of the second semiconductor laser pumping source is greater than the power of the first semiconductor laser pumping source.

优选的，所述光纤主放大器包括第三半导体激光泵浦源、第三合束器、第三保偏增益光纤以及光纤准直器；Preferably, the optical fiber main amplifier includes a third semiconductor laser pump source, a third beam combiner, a third polarization-maintaining gain fiber, and a fiber collimator;

所述第三半导体激光泵浦源用于为所述光纤正放大器提供第三泵浦光；The third semiconductor laser pump source is used to provide third pump light for the optical fiber positive amplifier;

所述第三合束器用于将所述第三泵浦光和所述第二线偏振激光耦合至所述第三保偏增益光纤中；the third beam combiner is used for coupling the third pump light and the second linearly polarized laser into the third polarization-maintaining gain fiber;

所述第三保偏增益光纤用于将所述第三泵浦光的能量转化为所述可调谐脉冲线偏振泵浦激光的能量，对所述光纤预放大器输出的第二线偏振激光功率进行放大；The third polarization-maintaining gain fiber is used to convert the energy of the third pump light into the energy of the tunable pulsed linearly polarized pump laser, and amplify the power of the second linearly polarized laser output from the fiber preamplifier ;

所述光纤准直器用于对所述光纤主放大器输出的可调谐脉冲线偏振泵浦激光进行准直。The fiber collimator is used for collimating the tunable pulse linearly polarized pump laser output from the fiber main amplifier.

优选的，所述第三半导体激光泵浦源的功率大于所述第二半导体激光泵浦源的功率。Preferably, the power of the third semiconductor laser pumping source is greater than the power of the second semiconductor laser pumping source.

优选的，所述泵浦光耦合装置包括空间光隔离器、半波片以及缩束镜组；所述缩束镜组包括凸透镜和凹透镜。Preferably, the pump light coupling device includes a spatial optical isolator, a half-wave plate and a beam-contracting mirror group; the beam-contracting mirror group includes a convex lens and a concave lens.

优选的，所述谐振腔镜包括前腔镜和输出镜；Preferably, the cavity mirror includes a front cavity mirror and an output mirror;

所述前腔镜将所述光纤激光透射至所述非线性晶体中，再经过所述输出镜反射回所述非线性晶体中，所述信号光在所述前腔镜和所述输出镜之间振荡并反复通过所述非线性晶体，所述闲频光伴随所述信号光产生，从所述输出镜与所述信号光同路输出。The front cavity mirror transmits the fiber laser into the nonlinear crystal, and then reflects back into the nonlinear crystal through the output mirror, and the signal light is between the front cavity mirror and the output mirror. Oscillates and repeatedly passes through the nonlinear crystal, the idler light is generated along with the signal light, and is output from the output mirror in the same path as the signal light.

优选的，所述非线性晶体为周期极化晶体；Preferably, the nonlinear crystal is a periodically polarized crystal;

所述前腔镜镀有第一光学薄膜，所述第一光学薄膜对所述可调谐脉冲线偏振泵浦激光高透，对所述信号光高反，对所述闲频光高反；所述第一光学薄膜对所述可调谐脉冲线偏振泵浦激光的透过率＞95％，所述第一光学薄膜对所述信号光的反射率＞95％，所述第一光学薄膜对所述闲频光的反射率＞95％；The front cavity mirror is coated with a first optical film, and the first optical film is highly transparent to the tunable pulse linearly polarized pump laser, highly reflective to the signal light, and highly reflective to the idler light; The transmittance of the first optical film to the tunable pulsed linearly polarized pump laser>95%, the reflectance of the first optical film to the signal light>95%, the first optical film to all The reflectivity of the idler light is more than 95%;

所述输出镜镀有第二光学薄膜，所述第二光学薄膜对所述可调谐脉冲线偏振泵浦激光高反，对所述信号光部分反射，对所述闲频光高透；所述第二光学薄膜对所述可调谐脉冲线偏振泵浦激光的反射率＞95％，所述第二光学薄膜对所述信号光的反射率为70％，所述第二光学薄膜对所述闲频光的透射率＞95％。The output mirror is coated with a second optical film, and the second optical film is highly reflective to the tunable pulsed linearly polarized pump laser, partially reflects the signal light, and is highly transparent to the idler light; the The reflectivity of the second optical film to the tunable pulsed linearly polarized pump laser is >95%, the reflectivity of the second optical film to the signal light is 70%, and the second optical film to the idler The transmittance of frequency light>95%.

本发明提供的可调谐光参量振荡器包括光纤激光器、泵浦光耦合装置、非线性晶体、晶体温控装置和谐振腔镜：光纤激光器用于发射波长可调谐的泵浦激光；泵浦光耦合装置用于对泵浦光进行隔离、缩束和偏振态调节等，将泵浦光耦合至非线性晶体和谐振腔中；非线性晶体用于将泵浦光转换成信号光和闲频光；晶体温控装置用于控制非线性晶体的工作温度；谐振腔镜用于实现参量光的振荡。The tunable optical parametric oscillator provided by the present invention includes a fiber laser, a pump light coupling device, a nonlinear crystal, a crystal temperature control device and a resonator mirror: the fiber laser is used for emitting a wavelength-tunable pump laser; the pump light coupling The device is used to isolate, narrow and adjust the polarization state of the pump light, and couple the pump light into the nonlinear crystal and resonator; the nonlinear crystal is used to convert the pump light into signal light and idler light; The crystal temperature control device is used to control the working temperature of the nonlinear crystal; the resonator mirror is used to realize the oscillation of the parametric light.

本发明提供的可调谐光参量振荡器通过改变光纤激光器的波长，实现可调谐光参量振荡器的可调谐激光输出；即采用可调谐激光器作为泵浦源，无需改变晶体的角度、工作温度或极化周期，通过改变泵浦波长即可实现大范围快速可调谐激光输出。The tunable optical parametric oscillator provided by the present invention realizes the tunable laser output of the tunable optical parametric oscillator by changing the wavelength of the fiber laser; that is, the tunable laser is used as the pumping source, without changing the angle, working temperature or pole of the crystal. A wide range of fast tunable laser output can be achieved by changing the pump wavelength.

附图说明Description of drawings

图1是现有技术中扇形周期极化晶体示意图。FIG. 1 is a schematic diagram of a fan-shaped periodically polarized crystal in the prior art.

图2是现有技术中圆形端面周期极化晶体示意图。FIG. 2 is a schematic diagram of a circular end face periodically polarized crystal in the prior art.

图3是本发明一种实施例的可调谐光参量振荡器的结构示意图。FIG. 3 is a schematic structural diagram of a tunable optical parametric oscillator according to an embodiment of the present invention.

图4是本发明一种实施例中MgO:PPLN晶体的调谐关系图。FIG. 4 is a tuning relationship diagram of MgO:PPLN crystal in an embodiment of the present invention.

附图标记：Reference number:

第一LD泵浦源1、第一合束器2、第一保偏增益光纤3、可调谐光纤滤波器4、第一光纤隔离器5、光纤耦合器6、光纤声光调制器7、第二LD泵浦源8、第二合束器9、第二保偏增益光纤10、第二光纤隔离器11、第三LD泵浦源12、第三合束器13、第三保偏增益光纤14、光纤准直器15、光隔离器16、半波片17、凸透镜18、凹透镜19、前腔镜20、非线性晶体21、晶体温控炉22、输出镜23。The first LD pump source 1, the first beam combiner 2, the first polarization-maintaininggain fiber 3, the tunable fiber filter 4, the first fiber isolator 5, thefiber coupler 6, the fiber acousto-optic modulator 7, the first TwoLD pump sources 8, a second beam combiner 9, a second polarization-maintaininggain fiber 10, asecond fiber isolator 11, a thirdLD pump source 12, a third beam combiner 13, and a third polarization-maintaininggain fiber 14.Fiber collimator 15,optical isolator 16, half-wave plate 17, convexlens 18,concave lens 19,front cavity mirror 20,nonlinear crystal 21, crystaltemperature control furnace 22,output mirror 23.

具体实施方式Detailed ways

为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及具体实施例，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用以解释本发明，而不构成对本发明的限制。In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

如图3所示，为本发明一种实施例的可调谐光参量振荡器，从图中可以看出，该可调谐光参量振荡器的组成包括：用于输出可调谐脉冲线偏振泵浦激光的光纤激光器、用于对可调谐脉冲线偏振泵浦激光进行隔离、缩束和偏振态调节的泵浦光耦合装置，用于产生信号光和闲频光的非线性晶体21，用于控制非线性晶体21工作温度的晶体温控炉22，以及用于信号光振荡的谐振腔镜。As shown in FIG. 3 , it is a tunable optical parametric oscillator according to an embodiment of the present invention. It can be seen from the figure that the composition of the tunable optical parametric oscillator includes: a tunable pulse linearly polarized pump laser for outputting fiber laser, pump light coupling device for isolation, beam reduction and polarization state adjustment of tunable pulsed linearly polarized pump laser, nonlinear crystal for generating signal light and idler light, for controlling non-linear A crystal temperature-controlledfurnace 22 for the working temperature of thelinear crystal 21, and a resonator mirror for signal light oscillation.

具体实施例中，光纤激光器包括1个用于产生可调谐脉冲线偏振种子激光的种子光纤激光器、1个用于对可调谐脉冲线偏振种子激光进行功率预放大的光纤预放大器，1个用于对可调谐脉冲线偏振激光进行功率放大的光纤主放大器。具体的，种子光纤激光器用于产生第一线偏振激光，作为光纤预放大器的可调谐脉冲线偏振种子激光；光纤预放大器用于对第一线偏振激光进行功率预放大，产生第二线偏振激光；光纤主放大器用于对第二线偏振激光进行功率放大，产生可调谐脉冲线偏振泵浦激光。In a specific embodiment, the fiber laser includes a seed fiber laser for generating a tunable pulsed linearly polarized seed laser, a fiber preamplifier for pre-amplifying the power of the tunable pulsed linearly polarized seed laser, and one for Fiber main amplifier for power amplification of tunable pulsed linearly polarized laser light. Specifically, the seed fiber laser is used to generate the first linearly polarized laser light as a tunable pulsed linearly polarized seed laser of the fiber pre-amplifier; the fiber pre-amplifier is used to pre-amplify the power of the first linearly polarized laser light to generate the second linearly polarized laser light; The fiber main amplifier is used to amplify the power of the second linearly polarized laser to generate a tunable pulsed linearly polarized pump laser.

种子光纤激光器用于产生第一线偏振激光，作为光纤预放大器的可调谐脉冲线偏振种子激光，具体可以输出1μm波段激光，也可以输出2μm波段激光；当种子光纤激光器中的第一保偏增益光纤3采用保偏掺Yb光纤时，输出1μm波段激光；当种子光纤激光器中的第一保偏增益光纤3采用保偏掺Tm、掺Ho或者Tm/Ho共掺光纤时，则输出1.9μm～2.1μm区间波段激光。The seed fiber laser is used to generate the first linearly polarized laser, as the tunable pulse linearly polarized seed laser of the fiber pre-amplifier, which can specifically output the 1μm band laser or the 2μm band laser; when the first polarization maintaining gain in the seed fiber laser When thefiber 3 is a polarization-maintaining doped Yb fiber, the output is 1 μm band laser; when the first polarization-maintaininggain fiber 3 in the seed fiber laser is a polarization-maintaining Tm-doped, Ho-doped or Tm/Ho co-doped fiber, the output is 1.9 μm～ 2.1μm interval band laser.

种子光纤激光器产生第一线偏振激光，具体实施方式中，种子光纤激光器采用环形腔设计，具体包括第一半导体激光(LD)泵浦源1、第一合束器2、第一保偏增益光纤3、可调谐光纤滤波器4、第一光纤隔离器5、光纤耦合器6以及光纤声光调制器7；其中，种子光纤激光器产生第一线偏振激光，第一LD泵浦源1输出976nm第一泵浦光，通过第一合束器2将第一泵浦光和未耦合输出的第一线偏振激光耦合至第一保偏增益光纤3中。The seed fiber laser generates a first linearly polarized laser. In a specific implementation, the seed fiber laser adopts a ring cavity design, which specifically includes a first semiconductor laser (LD) pump source 1, a first beam combiner 2, and a first polarization-maintaining gain fiber. 3. The tunable fiber filter 4, the first fiber isolator 5, thefiber coupler 6 and the fiber acousto-optic modulator 7; wherein, the seed fiber laser generates the first linearly polarized laser light, and the first LD pump source 1 outputs the first 976 nm laser. A pump light, the first pump light and the uncoupled output first linearly polarized laser are coupled into the first polarization-maintaininggain fiber 3 through the first beam combiner 2 .

具体的，第一保偏增益光纤3采用保偏掺Yb光纤，在吸收第一泵浦光能量后通过受激辐射产生线偏振1μm波段激光。激光波长通过可调谐光纤滤波器4调谐，可调谐光纤滤波器4是一个带通滤波器，可通过电控调节其透射谱的中心波长，从而实现对种子光纤激光器的波长调谐，具体实施例中波长调谐范围为1.01μm～1.09μm。第一光纤隔离器5使种子激光在环形腔内单向传输。光纤声光调制器7对种子光纤激光器进行声光调Q，产生脉冲激光。种子激光通过光纤耦合器6输出至光纤预放大器中。Specifically, the first polarization-maintaininggain fiber 3 is a polarization-maintaining Yb-doped fiber, which generates linearly polarized 1 μm-band laser light through stimulated radiation after absorbing the energy of the first pump light. The laser wavelength is tuned by a tunable fiber filter 4. The tunable fiber filter 4 is a band-pass filter, and the center wavelength of its transmission spectrum can be adjusted by electronic control, thereby realizing the wavelength tuning of the seed fiber laser. The wavelength tuning range is 1.01μm～1.09μm. The first fiber isolator 5 makes the seed laser transmit unidirectionally in the ring cavity. The fiber acousto-optic modulator 7 performs acousto-optic Q-switching on the seed fiber laser to generate pulsed laser light. The seed laser is output to the fiber preamplifier through thefiber coupler 6 .

光纤预放大器产生第二线偏振激光，具体实施方式中，包括第二半导体激光(LD)泵浦源8、第二合束器9、第二保偏增益光纤10以及第二光纤隔离器11。具体由第二LD泵浦源8提供976nm第二泵浦光，其功率要高于第一LD泵浦源1，使得光纤预放大器在更高功率泵浦情况下获得高功率的第二线偏振激光输出。第二合束器9将第二泵浦光和光纤耦合器6输出的第一线偏振激光耦合至光纤预放大器的第一双包层保偏增益光纤10中，第二保偏增益光纤10可以为双包层保偏掺Yb光纤，通过使用双包层，能够承受更高的泵浦功率，在吸收泵浦光能量后对种子激光进行功率预放大。经过预防大后的第二线偏振激光经过第二光纤隔离器11进入光纤主放大器，第二光纤隔离器11可防止光纤主放大器后向反射光返回光纤预放大器，避免造成器件损伤。The fiber pre-amplifier generates a second linearly polarized laser, and in a specific implementation, includes a second semiconductor laser (LD) pumpsource 8 , asecond beam combiner 9 , a second polarization-maintaininggain fiber 10 and asecond fiber isolator 11 . Specifically, the secondLD pump source 8 provides a 976 nm second pump light, and its power is higher than that of the first LD pump source 1, so that the fiber pre-amplifier can obtain a high-power second linearly polarized laser under the condition of higher power pumping output. Thesecond beam combiner 9 couples the second pump light and the first linearly polarized laser output from thefiber coupler 6 into the first double-clad polarization-maintaininggain fiber 10 of the fiber preamplifier, and the second polarization-maintaininggain fiber 10 can be For the double-clad polarization-maintaining Yb-doped fiber, by using double-cladding, it can withstand higher pump power, and pre-amplify the seed laser power after absorbing the pump light energy. The second linearly polarized laser after the prevention passes through thesecond fiber isolator 11 and enters the fiber main amplifier. Thesecond fiber isolator 11 can prevent the back-reflected light of the fiber main amplifier from returning to the fiber pre-amplifier to avoid device damage.

光纤主放大器的结构与光纤预放大器的结构类似，光纤主放大器产生可调谐脉冲线偏振泵浦激光；具体实施方式中，光纤主放大器包括第三半导体激光(LD)泵浦源12、第三合束器13、第三保偏增益光纤14以及光纤准直器15。具体由第三LD泵浦源12提供976nm第三泵浦光，其功率要高于第二LD泵浦源8，第三LD泵浦源12可以为1个，2个或多个，具体其总功率高于第二LD泵浦源8即可。第三合束器13将第三泵浦光和第二线偏振激光耦合至光纤主放大器的第三保偏增益光纤14中，第三保偏增益光纤14可以为双包层保偏掺Yb光纤，在吸收第三泵浦光能量后，将第三泵浦光的能量转化为可调谐脉冲线偏振泵浦激光的能量。经过放大后的可调谐脉冲线偏振泵浦激光经光纤准直器15准直输出进入泵浦光耦合装置。The structure of the optical fiber main amplifier is similar to that of the optical fiber pre-amplifier. The optical fiber main amplifier generates a tunable pulse linearly polarized pump laser; in a specific implementation, the optical fiber main amplifier includes a third semiconductor laser (LD) pumpsource 12, athird A beamer 13 , a third polarization-maintaininggain fiber 14 and afiber collimator 15 . Specifically, the thirdLD pump source 12 provides a 976 nm third pump light, and its power is higher than that of the secondLD pump source 8. The thirdLD pump source 12 can be one, two or more. The total power may be higher than that of the secondLD pump source 8 . Thethird beam combiner 13 couples the third pump light and the second linearly polarized laser light into the third polarization-maintaininggain fiber 14 of the fiber main amplifier, and the third polarization-maintaininggain fiber 14 may be a double-clad polarization-maintaining Yb-doped fiber, After absorbing the energy of the third pump light, the energy of the third pump light is converted into the energy of the tunable pulsed linearly polarized pump laser. The amplified tunable pulse linearly polarized pump laser is collimated and outputted by thefiber collimator 15 into the pump optical coupling device.

泵浦光耦合装置包括空间光隔离器16、半波片17以及缩束镜组。光纤激光首先通过空间光隔离器16，空间光隔离器16可防止可调谐光参量振荡器后向反射光返回光纤主放大器，避免造成器件损伤。空间光隔离器16输出的可调谐脉冲线偏振泵浦激光通过半波片17调整偏振态以满足最佳的相位匹配条件，随后通过缩束镜组进行缩束。缩束镜组由凸透镜18与凹透镜19组成，通过凸透镜18与凹透镜19配合来缩小可调谐脉冲线偏振泵浦激光的光斑直径，具体可通过选用不同的焦距组合来实现不同倍率的缩束。The pump light coupling device includes a spatialoptical isolator 16 , a half-wave plate 17 and a beam reducing mirror group. The fiber laser first passes through the spatialoptical isolator 16, and the spatialoptical isolator 16 can prevent the back-reflected light of the tunable optical parametric oscillator from returning to the optical fiber main amplifier, so as to avoid device damage. The tunable pulse linearly polarized pump laser output from the spatialoptical isolator 16 adjusts the polarization state through the half-wave plate 17 to satisfy the optimal phase matching condition, and then undergoes beam reduction through the beam reduction mirror group. The beam-reducing lens group is composed of aconvex lens 18 and aconcave lens 19. The beam spot diameter of the tunable pulsed linearly polarized pump laser can be reduced by the cooperation of theconvex lens 18 and theconcave lens 19. Specifically, different focal length combinations can be selected to achieve different magnifications.

可调谐脉冲线偏振泵浦激光经过泵浦光耦合装置后进入非线性晶体21和谐振腔，具体的实施方式中，非线性晶体21为周期极化晶体，更具体的，非线性晶体21可以为掺MgO周期极化铌酸锂(MgO:PPLN)晶体，或者周期极化钽酸锂晶体等；以MgO:PPLN晶体为例，MgO:PPLN晶体基于准相位匹配将光纤激光转化为信号光和闲频光，具体实施例中，MgO:PPLN晶体的极化周期为29.5μm。晶体温控炉22用于控制MgO:PPLN晶体的工作温度，实施例中工作温度为100℃。The tunable pulse linearly polarized pump laser enters thenonlinear crystal 21 and the resonant cavity after passing through the pump optical coupling device. In a specific implementation, thenonlinear crystal 21 is a periodically polarized crystal. More specifically, thenonlinear crystal 21 can be MgO-doped periodically polarized lithium niobate (MgO:PPLN) crystal, or periodically polarized lithium tantalate crystal, etc. Taking MgO:PPLN crystal as an example, MgO:PPLN crystal converts fiber laser into signal light and idler based on quasi-phase matching In the specific embodiment, the polarization period of the MgO:PPLN crystal is 29.5 μm. The crystaltemperature control furnace 22 is used to control the working temperature of the MgO:PPLN crystal, and the working temperature is 100° C. in the embodiment.

如图4所示，本发明实施例中MgO:PPLN晶体的极化周期为29.5μm，工作温度为100℃，当泵浦光在1.01μm～1.09μm泵浦区间内调谐时，会输出1.47μm～1.51μm波段可调谐的信号光和3.10μm～3.93μm波段可调谐的闲频光；通过调谐可调谐脉冲线偏振泵浦激光的波长，在不改变周期极化晶体极化周期的情况下，可以调谐信号光的波长和闲频光的波长。As shown in FIG. 4 , in the embodiment of the present invention, the polarization period of the MgO:PPLN crystal is 29.5 μm, and the operating temperature is 100° C. When the pump light is tuned in the pump range of 1.01 μm to 1.09 μm, the output will be 1.47 μm. Tunable signal light in the ~1.51μm band and tunable idler light in the 3.10μm ~ 3.93μm band; by tuning the wavelength of the tunable pulsed linearly polarized pump laser, without changing the polarization period of the periodically polarized crystal, The wavelength of the signal light and the wavelength of the idler light can be tuned.

当可调谐脉冲线偏振泵浦激光在1.01μm～1.09μm之间调谐时，对应的信号光和闲频光调谐范围分别为1.47μm～1.51μm和3.10μm～3.93μm。谐振腔包括前腔镜20和输出镜23，通过采用泵浦光双通信号光单谐振的技术方案以提高光光转换效率；具体的，前腔镜20将可调谐脉冲线偏振泵浦激光透射至MgO:PPLN晶体21中后再经过输出镜23反射回MgO:PPLN晶体，使可调谐脉冲线偏振泵浦激光通过MgO:PPLN晶体2次，信号光在前腔镜20和输出镜23之间振荡并反复通过MgO:PPLN晶体，闲频光伴随信号光产生，直接从输出镜23与信号光同路输出。When the tunable pulsed linearly polarized pump laser is tuned between 1.01 μm and 1.09 μm, the corresponding tuning ranges of signal light and idler light are 1.47 μm to 1.51 μm and 3.10 μm to 3.93 μm, respectively. The resonant cavity includes afront cavity mirror 20 and anoutput mirror 23, and the optical-to-optical conversion efficiency is improved by adopting the technical solution of pump light double-pass signal light single resonance; specifically, thefront cavity mirror 20 transmits the tunable pulse linearly polarized pump laser light After reaching the MgO:PPLN crystal 21, it is reflected back to the MgO:PPLN crystal through theoutput mirror 23, so that the tunable pulse linearly polarized pump laser passes through the MgO:PPLN crystal twice, and the signal light is between thefront cavity mirror 20 and theoutput mirror 23. Oscillating and repeatedly passing through the MgO:PPLN crystal, the idler light is generated along with the signal light, and is directly output from theoutput mirror 23 in the same path as the signal light.

具体实施方式中，前腔镜20镀有第一光学薄膜，该第一光学薄膜对1.01μm～1.09μm波段泵浦光高透，对1.47μm～1.51μm波段信号光和3.10μm～3.93μm波段闲频光高反可调谐脉冲线偏振泵浦激光，具体的，1.01μm～1.09μm波段泵浦光透过率＞95％；1.47μm～1.51μm波段信号光的反射率＞95％；3.10μm～3.93μm波段闲频光的反射率＞95％；以便将泵浦光透射至MgO:PPLN晶体中，并对信号光和闲频光进行反射。In the specific embodiment, thefront cavity mirror 20 is coated with a first optical film, the first optical film is highly transparent to the pump light in the 1.01μm-1.09μm band, and is transparent to the 1.47μm-1.51μm band signal light and 3.10μm-3.93μm band. High-inversion tunable pulsed linearly polarized pump laser of idler frequency light, specifically, the transmittance of pump light in the band of 1.01μm～1.09μm>95%; the reflectivity of signal light in the band of 1.47μm～1.51μm>95%; 3.10μm The reflectivity of the idler light in the ~3.93 μm band is >95%; in order to transmit the pump light into the MgO:PPLN crystal, and reflect the signal light and the idler light.

输出镜23镀有第二光学薄膜，该第二光学薄膜对1.01μm～1.09μm波段泵浦光高反，对1.47μm～1.51μm波段信号光部分反射，对3.10μm～3.93μm波段闲频光高透，具体的，1.01μm～1.09μm波段泵浦光反射率＞95％；1.47μm～1.51μm波段信号光的反射率为70％；3.10μm～3.93μm波段闲频光的透射率＞95％；以便将泵浦光反射回MgO:PPLN晶体中，并反射部分信号光使其在谐振腔中振荡，同时将信号光和闲频光耦合输出。Theoutput mirror 23 is coated with a second optical film, the second optical film is highly reflective to the pump light in the 1.01 μm to 1.09 μm band, partially reflects the signal light in the 1.47 μm to 1.51 μm band, and partially reflects the idler light in the 3.10 μm to 3.93 μm band. High transmittance, specifically, the reflectivity of pump light in the 1.01μm～1.09μm band is more than 95%; the reflectivity of the signal light in the 1.47μm～1.51μm band is 70%; the transmittance of the idler light in the 3.10μm～3.93μm band is more than 95% %; so that the pump light is reflected back into the MgO:PPLN crystal, and part of the signal light is reflected to make it oscillate in the resonant cavity, while the signal light and the idler light are coupled out.

本发明具体实施方式中，可调谐光参量振荡器输出的信号光和闲频光波长与晶体材料、极化周期、工作温度和泵浦波长有关；除了上述具体实施例中用到的MgO:PPLN晶体，当采用其他非线性晶体，晶体极化周期改变、晶体材料改变或者泵浦波段改变，信号光和闲频光的波段也会改变，则前腔镜20和输出镜23表面的镀膜也相应予以改变。In the specific embodiment of the present invention, the wavelengths of the signal light and idler light output by the tunable optical parametric oscillator are related to the crystal material, polarization period, operating temperature and pump wavelength; except for the MgO:PPLN used in the above specific embodiments When other nonlinear crystals are used, the polarization period of the crystal, the crystal material, or the pump band changes, and the bands of the signal light and idler light also change, so the coatings on the surfaces of thefront cavity mirror 20 and theoutput mirror 23 are also corresponding. be changed.

本发明提供的可调谐光参量振荡器通过改变可调谐泵浦激光器的波长，实现可调谐光参量振荡器的可调谐激光输出；即采用可调谐激光器作为泵浦源，无需改变晶体的角度、工作温度或极化周期，通过改变泵浦波长即可实现大范围快速可调谐激光输出。The tunable optical parametric oscillator provided by the present invention realizes the tunable laser output of the tunable optical parametric oscillator by changing the wavelength of the tunable pump laser; A wide range of fast tunable laser output can be achieved by changing the pump wavelength depending on temperature or polarization period.

在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

尽管上面已经示出和描述了本发明的实施例，可以理解的是，上述实施例是示例性的，不能理解为对本发明的限制。本领域的普通技术人员在本发明的范围内可以对上述实施例进行变化、修改、替换和变型。Although the embodiments of the present invention have been shown and described above, it is to be understood that the above-described embodiments are exemplary and should not be construed to limit the present invention. Variations, modifications, substitutions, and alterations to the above-described embodiments can be made by those of ordinary skill in the art within the scope of the present invention.

以上本发明的具体实施方式，并不构成对本发明保护范围的限定。任何根据本发明的技术构思所做出的各种其他相应的改变与变形，均应包含在本发明权利要求的保护范围内。The above specific embodiments of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.