CN110932085B - A tunable laser with cascaded stimulated electromagnetic coupler scattering and stimulated Raman scattering and its working method - Google Patents
A tunable laser with cascaded stimulated electromagnetic coupler scattering and stimulated Raman scattering and its working method Download PDFInfo
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Abstract
本发明涉及一种级联受激电磁耦子散射和受激拉曼散射的可调谐激光器及其工作方法，该激光器包括二极管激光器、光学耦合镜片、激光谐振腔、斯托克斯参量振荡腔和旋转位移平台；二极管激光器与光学耦合镜片相连接，光学耦合镜片与激光谐振腔相连接；斯托克斯参量振荡腔与激光谐振腔之间的角度为1°‑7°；斯托克斯参量振荡腔后腔镜和斯托克斯参量振荡腔输出镜均设置在旋转位移平台上，通过调节旋转位移平台实现斯托克斯参量振荡腔和激光谐振腔之间的角度调谐，输出不同波长的受激拉曼激光。本发明成功实现了一个激光器可以同时级联两种不同受激散射，通过角度调谐输出不同波长的受激拉曼激光。
The invention relates to a tunable laser with cascaded stimulated electromagnetic coupler scattering and stimulated Raman scattering and a working method thereof. The laser comprises a diode laser, an optical coupling lens, a laser resonant cavity, a Stokes parametric oscillation cavity and a Rotation displacement platform; diode laser is connected with optical coupling lens, and optical coupling lens is connected with laser resonator; the angle between Stokes parameter oscillation cavity and laser resonator is 1°‑7°; Stokes parameter The rear cavity mirror of the oscillator and the output mirror of the Stokes parametric oscillator are both set on the rotating displacement platform. By adjusting the rotating displacement platform, the angle tuning between the Stokes parametric oscillator and the laser resonator can be achieved, and the output of different wavelengths can be achieved. Stimulated Raman Laser. The invention successfully realizes that one laser can cascade two different stimulated scatterings at the same time, and output stimulated Raman lasers with different wavelengths through angle tuning.
Description
Technical Field
The invention relates to a tunable laser for cascade excited electromagnetic couple scattering and excited Raman scattering and a working method thereof, belonging to the technical field of laser frequency conversion.
Background
Stimulated electromagnetic coupling Scattering (SPS) means that when laser with certain intensity is incident into a nonlinear crystal, laser photons are coupled with transverse optical phonons in the nonlinear crystal, and one pump laser photon (with the frequency v)PWave vector of kP) Forming a Stokes photon (frequency v)SWave vector of kS) And an electromagnetic couple (frequency v)TWave vector of kT). The energy conservation (v) between the pump laser photons, the stokes photons and the electromagnetic couplings needs to be satisfiedP＝νS+νT) And satisfy conservation of momentum (k)P＝kS+kT) Under the condition, the phase matching condition of momentum conservation is a non-collinear phase matching relationship, so that the angular dispersion of Stokes light can be caused, namely the Stokes light with different frequencies is generated at different angles, the Stokes light at different angles can be oscillated by the optical resonant cavity, and the Stokes laser with specific frequency is output, so that the tunable output of the Stokes laser can be realized by angle tuning in the scattering of the excited electromagnetic couple.
Stimulated Raman Scattering (SRS) refers to a process in which a laser with a certain intensity and a substance molecule have a strong inelastic interaction, and the energy of a laser photon is absorbed by the substance molecule to emit a stokes photon and a phonon. Pump photons (frequency v)PWave vector of kP) Stokes photons (frequency vSWave vector of kS) And phonons (frequency v)RWave vector of kR) The energy conservation (v) also needs to be satisfied betweenP＝νS+νR) And conservation of momentum (k)P＝kS+kR) Under the condition, the phase matching relation of momentum conservation is collinear phase matching, namely the pump light and the Stokes light generated by the pump light are on the same straight line, so that the physical mechanism of the collinear phase matching determines that the tunable output of the stimulated Raman laser cannot be realized through angle tuning in the stimulated Raman scattering. Due to the fact that the types of nonlinear crystals capable of being used for stimulated Raman scattering are various, the pumping source and the Raman nonlinear crystal share one resonant cavity, and the resonant cavity is relatively simple to build and adjust, the laser technology based on the stimulated Raman scattering is mature.
However, the only nonlinear crystal that can produce stimulated electromagnetic couple scattering has been LiNBO so far3、KTiOPO4(KTP)、KTiOAsO4(KTA)、RbTiOPO4(RTP) of the above, therefore, the laser technology based on the stimulated electromagnetic couple scattering has been developed later, but with the continuous efforts of researchers, there have been many reports on the technologyAnd (4) carrying out the following steps. By stimulated electromagnetic coupling scattering or stimulated Raman scattering, at a frequency vPThe pump laser can realize frequency conversion, and the generated frequency is vSWhen the frequency generated by the pump light is v in the SPS (SRS) processS1After the first-order Stokes laser reaches certain intensity, the frequency v can be generatedS2Second-order stokes scatter light, and so on, this case is called tandem sps (srs). However, no relevant attempts have been made by researchers to obtain lasers utilizing both of these two different stimulated scatterings to achieve both of the cascade stimulated electromagnetic couple scattering and the stimulated raman scattering.
The frequency tuning of the stimulated raman scattering performed at present is generally realized by the temperature change of the raman crystal, but the tuning range of the tuning method is very small, the tuning range is usually within a few nanometers, and the use complexity and the cost of the whole laser are increased.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a tunable laser for cascading excited electromagnetic coupler scattering and excited Raman scattering, which realizes the cascading of the excited electromagnetic coupler scattering and the excited Raman scattering and simultaneously realizes the tunable output of the excited Raman laser by the angle tuning between a laser resonant cavity and a Stokes parametric oscillation cavity.
The invention also provides a working method of the cascade excited electromagnetic couple scattering and excited Raman scattering tunable laser.
The technical scheme of the invention is as follows:
a tunable laser for cascade excited electromagnetic couple scattering and excited Raman scattering comprises a diode laser, an optical coupling lens, a laser resonant cavity, a Stokes parametric oscillation cavity and a rotary displacement platform; the diode laser is connected with an optical coupling lens, and the optical coupling lens is connected with the laser resonant cavity;
the laser resonant cavity comprises a laser resonant cavity rear cavity mirror and an Nd which are arranged along a light path in sequence: YAG laser crystal, acousto-optic Q-switching device, polarization beam splitter prism, nonlinear crystal and laser resonant cavity output mirror;
the Stokes parametric oscillation cavity comprises the nonlinear crystal, a Stokes parametric oscillation cavity rear cavity mirror and a Stokes parametric oscillation cavity output mirror, the Stokes parametric oscillation cavity rear cavity mirror and the Stokes parametric oscillation cavity output mirror are respectively arranged on two sides of the nonlinear crystal, and the angle between the Stokes parametric oscillation cavity and the laser resonant cavity is 1-7 degrees;
the Stokes parametric oscillation cavity rear cavity mirror and the Stokes parametric oscillation cavity output mirror are both arranged on the rotary displacement platform, angle tuning between the Stokes parametric oscillation cavity and the laser resonant cavity is realized by adjusting the rotary displacement platform, and stimulated Raman lasers with different wavelengths are output.
The working principle of the tunable laser provided by the invention is as follows: the diode laser is used as a light source and outputs continuous laser; the laser is in a laser oscillation cavity, and the laser output by the diode laser is in a gain medium Nd: YAG laser crystal is amplified and converted into pump laser through light stimulated radiation; the acousto-optic Q-switching device can generate Q-switching pulses with certain frequency so as to realize the stimulated SPS and the stimulated SRS;
in the laser resonant cavity, after the nonlinear crystal is acted by pump laser, because the gain coefficient of the first order SPS-Stokes generated by the stimulated electromagnetic coupling scattering in the Stokes resonant cavity is larger than that of the first order SRS-Stokes generated by the stimulated Raman scattering in the laser resonant cavity, the stimulated electromagnetic coupling scattering in the nonlinear crystal takes precedence over the stimulated Raman scattering to generate first order SPS-Stokes laser.
Through the angle tuning of the Stokes parametric oscillation cavity and the laser resonant cavity, the first-order SPS-Stokes laser is used as pump light to generate first-order SRS-Stokes laser in the direction of the Stokes parametric oscillation cavity.
According to the invention, the material of the nonlinear crystal is Rubidium Titanyl Phosphate (RTP), and the angle between the Stokes parametric oscillation cavity and the laser resonant cavity is 1.5-5 degrees.
According to the invention, preferably, non-linearThe crystal material is lithium niobate (LiNbO)3) The angle between the Stokes parametric oscillation cavity and the laser resonant cavity is 1-3 degrees.
According to the invention, the material of the nonlinear crystal is potassium titanyl phosphate (KTP), and the angle between the Stokes parametric oscillation cavity and the laser resonant cavity is 1.2-6.5 degrees.
According to the invention, the material of the nonlinear crystal is potassium titanyl arsenate (KTA), and the angle between the Stokes parametric oscillation cavity and the laser resonant cavity is 1.8-7 degrees.
The stimulated Raman laser with different tuning output wavelengths can be tuned by adjusting the angle between the laser resonant cavity and the Stokes parametric oscillation cavity aiming at different nonlinear crystals, the tuning range is large, and the device is simple.
Preferably, according to the invention, the output wavelength of the diode laser is 808 nm;
one end of the rear cavity mirror of the laser resonant cavity is plated with an anti-reflection film of 808nm, and the other end of the rear cavity mirror of the laser resonant cavity is simultaneously plated with a high anti-reflection film of 1064nm and a high transmission film of 808nm by evaporation; the transmittance of the 808nm antireflection film is more than 99.8%, the reflectivity of the 1064nm high-reflection film is more than 99.8%, and the transmittance of the 808nm high-transmission film is more than 98%.
On one hand, the laser with the wavelength of 808nm can enter Nd as much as possible: YAG laser crystal is made in Nd: the YAG laser crystal is converted into 1064nm laser through light stimulated radiation amplification, and on the other hand, a 1064nm high-reflection film is plated, so that 1064nm light serving as an SPS pumping source can form laser oscillation of a sufficient cavity, SPS-Stokes laser can be generated as much as possible, and the efficiency of a laser is improved.
A high reflection film in the wavelength range of 1064nm-1090nm and a high transmission film in the wavelength range of 1090nm-1200nm are evaporated on an output mirror of the laser resonant cavity; the reflectivity of the high-reflection film in the wavelength range of 1064nm-1090nm is more than 99.8%, and the transmittance of the high-transmission film in the wavelength range of 1090nm-1200nm is more than 80%.
In the laser resonant cavity, the coating of the output mirror of the laser resonant cavity ensures that the pumping laser forms stable oscillation in the laser resonant cavity and prevents the occurrence of the scattering of the cascade excited electromagnetic coupler.
Preferably, a high-reflection film in the wavelength range of 1050nm-1090nm, a partial transmission film in the wavelength range of 1100nm-1130nm and a high-transmission film in the wavelength range of 1140nm-1220nm are evaporated on the output mirror of the Stokes parametric oscillation cavity; the reflectivity of the high reflection film in the wavelength range of 1050nm-1090nm is more than 99.5%, the transmittance of a part of the high transmission film in the wavelength range of 1100nm-1130nm is 5% -30%, and the transmittance of the high transmission film in the wavelength range of 1140nm-1220nm is more than 80%.
In the Stokes parametric oscillation cavity, the coating design of an output mirror of the Stokes parametric oscillation cavity enables the cascade stimulated Raman scattering in the Stokes parametric oscillation cavity to be inhibited, and only first-order SRS-Stokes laser is generated in the Stokes parametric oscillation cavity.
The rear cavity mirror of the Stokes parametric oscillation cavity is evaporated with a high-reflection film within the wavelength range of 1000nm-1200nm, and the reflectivity of the high-reflection film within the wavelength range of 1000nm-1200nm is more than 99.8%.
The coating of the rear cavity mirror of the Stokes parametric oscillation cavity relates to the first-order SPS-Stokes laser high reflection of different wavelengths generated by scattering of an excited electromagnetic coupler, and ensures the high intensity of the first-order SPS-Stokes laser in the Stokes parametric oscillation cavity.
According to the invention, the two ends of the nonlinear crystal are preferably evaporated with the antireflection film in the wavelength range of 1000nm-1200nm, and the transmittance of the antireflection film in the wavelength range of 1000nm-1200nm is more than 99.8%.
According to a preferred embodiment of the invention, the Nd: the YAG laser crystal is characterized in that 808nm antireflection films and 1064nm antireflection films are respectively vapor-plated at two ends of the YAG laser crystal, 1064nm antireflection films are respectively plated at two ends of the acousto-optic Q-switching device, and the transmittances of the 808nm antireflection films and the 1064nm antireflection films are greater than 99.8%.
Nd: YAG laser crystal amplifies and converts laser with wavelength of 808nm into laser with wavelength of 1064nm through stimulated radiation; pulse laser with a certain repetition frequency can be formed through the acousto-optic Q-switching device.
According to a preferred embodiment of the invention, the Nd: the cooling temperature of the YAG laser crystal and the nonlinear crystal is 20 ℃.
The working method of the cascade excited electromagnetic couple scattering and stimulated Raman scattering tunable laser comprises the following steps:
(1) laser light generated by the diode laser is coupled into the laser resonant cavity through the optical coupling lens, and passes through the Nd: the YAG laser crystal generates Q-switched pump laser under the action of stimulated radiation amplification and frequency adjustment of an acousto-optic Q-switching device, and the pump laser in the vertical polarization direction is output through a polarization beam splitter prism;
(2) the pumping laser acts on the nonlinear crystal, firstly, the stimulated electromagnetic couple scattering is generated, and the stimulated electromagnetic couple scattering is generated;
(3) the first-order SPS-Stokes laser generated by the stimulated electromagnetic coupler scattering is used as a pump light source to excite a nonlinear crystal, and stimulated Raman scattering is generated in the direction of a Stokes parametric oscillation cavity;
(4) the output mirror of the Stokes parametric oscillation cavity outputs stimulated Raman laser in different wavelength ranges through the angle tuning between the Stokes parametric oscillation cavity and the laser resonant cavity.
According to the invention, the angle tuning between the Stokes parametric oscillation cavity and the laser resonant cavity is realized by adjusting the rotary displacement platform.
The invention has the beneficial effects that:
1. the tunable laser provided by the invention is cascaded with two different stimulated scatterings, namely stimulated electromagnetic couple scattering and stimulated Raman scattering, and the range of laser spectrum is widened. In the tunable laser, the stimulated electromagnetic coupling scattering can be realized in the nonlinear crystal by meeting the phase matching condition of the stimulated electromagnetic coupling scattering, and first-order SPS-Stokes laser is generated in a Stokes parametric oscillation cavity; by designing the optical spectrum transmittance of the Stokes parametric oscillation cavity mirror, the first-order SPS-Stokes laser in the Stokes parametric oscillation cavity can be used as pump laser to realize stimulated Raman scattering in the nonlinear crystal again.
2. The invention can realize the tuning of stimulated Raman laser with different output wavelengths by adjusting the angle between the Stokes parametric oscillation cavity and the laser resonant cavity, has larger tuning range, provides a new idea for the tunable output of Raman light, and has simpler device.
3. The invention provides a simple thought for expanding the range of the obtained laser wavelength, namely, the stimulated Raman scattering laser with different wavelengths and different orders can be obtained by changing the transmittance of the Stokes output mirror at different wavelengths.
4. When the input pumping power of the tunable laser is 7.9W, the tunable laser can obtain the highest laser power output of 0.97W, and the conversion efficiency is higher and is 12.3%.
5. The laser wavelength output by the laser of the cascade excited electromagnetic coupler scattering and the excited Raman scattering can cover 1120nm-1200nm, so the laser can be used as a light source of tunable yellow laser, the yellow laser can be obtained after laser frequency doubling, the frequency tunable output of the yellow laser can be carried out, and the laser has wide application in the aspects of biomedicine, medical cosmetology, food and drug detection, atmospheric remote sensing, information storage and the like.
Drawings
FIG. 1 is a schematic diagram of an apparatus structure of a tunable laser according to the present invention;
FIG. 2 is a schematic diagram of variation of first order SPS-Stokes laser wavelength with angular tuning;
FIG. 3 is a graph of transmittance of a coating film on an output mirror of a Stokes parametric oscillation cavity;
FIG. 4 is a schematic diagram of the variation of first order SRS-Stokes laser wavelength with angle tuning;
fig. 5 shows that when the pumping power is 7.9W, different tuning angles correspond to the laser output powers of the tunable lasers at different wavelengths;
FIG. 6 is a graph showing the power input output relationship at a wavelength of 1118.6nm corresponding to the maximum output power;
1. diode laser, 2, coupling-out fiber, 3, optical coupling lens, 4, Nd: YAG laser crystal, 5, acousto-optic Q-switching device, 6, polarization beam splitter prism, 7, laser resonant cavity rear cavity mirror, 8, laser resonant cavity output mirror, 9, nonlinear crystal, 10, Stokes parametric oscillation cavity rear cavity mirror, 11, Stokes parametric oscillation cavity output mirror, 12, pumping laser beam, 13, Stokes laser beam, 14 and rotary displacement platform.
Detailed Description
The invention is further described below by reference to the drawings and examples of the specification, but is not limited thereto.
Example 1
A tunable laser for cascade excited electromagnetic couple scattering and excited Raman scattering is shown in figure 1 and comprises a diode laser 1, an optical coupling lens 3, a laser resonant cavity, a Stokes parametric oscillation cavity and a rotary displacement platform 14; the diode laser 1 is connected with the optical coupling lens 3, and the optical coupling lens 3 is connected with the laser resonant cavity;
the wavelength output by the diode laser 1 is 808 nm; the diode laser 1 is connected with an optical coupling lens 3 through a coupling output optical fiber 2, and light is coupled into the laser resonant cavity through the optical coupling lens 3.
The laser resonant cavity comprises a laser resonant cavity rear cavity mirror 7 and an Nd which are arranged along a light path in sequence: YAG laser crystal 4, acousto-optic Q-switching device 5, polarization beam splitter prism 6, nonlinear crystal 9 and laser resonant cavity output mirror 8; in this example, the nonlinear crystal 9 is Rubidium Titanyl Phosphate (RTP).
The Stokes parametric oscillation cavity comprises a nonlinear crystal 9, a Stokes parametric oscillation cavity rear cavity mirror 10 and a Stokes parametric oscillation cavity output mirror 11, the Stokes parametric oscillation cavity rear cavity mirror 10 and the Stokes parametric oscillation cavity output mirror 11 are respectively arranged on two sides of the nonlinear crystal 9, the angle between the Stokes parametric oscillation cavity and the laser resonant cavity is 1.5-5.5 degrees, the Stokes parametric oscillation cavity rear cavity mirror 10 and the Stokes parametric oscillation cavity output mirror 11 are both arranged on a rotary displacement platform 14, the angle tuning between the Stokes parametric oscillation cavity and the laser resonant cavity is realized by adjusting the rotary displacement platform 14, and stimulated Raman lasers with different wavelengths are output.
The course of the pump laser beam 12 in the laser resonator and the course of the stokes laser beam 13 in the stokes parametric oscillator cavity are shown in fig. 1.
The working principle of the tunable laser provided by the invention is as follows: the diode laser 1 is used as a light source and outputs continuous laser; the laser is in a laser oscillation cavity, and the 808nm laser output by the diode laser 1 passes through a gain medium Nd: the light stimulated radiation amplification process in the YAG laser crystal 4 is converted into 1064nm laser; the acousto-optic Q-switching device 5 can generate Q-switching pulses with certain frequency so as to realize the stimulated SPS and the stimulated SRS;
in the laser resonator, after the nonlinear crystal 9 is acted by the pump laser, because the gain coefficient of the first-order SPS-Stokes oscillated in the Stokes resonator generated by the stimulated electromagnetic coupler scattering is larger than that of the first-order SRS-Stokes generated by the stimulated Raman scattering, the stimulated electromagnetic coupler scattering in the nonlinear crystal 9 takes precedence over the stimulated Raman scattering to generate the first-order SPS-Stokes laser.
Through the angle tuning of the Stokes parametric oscillation cavity and the laser resonant cavity, the first-order SPS-Stokes laser is used as pump light to generate first-order SRS-Stokes laser in the direction of the Stokes parametric oscillation cavity.
Nd: the doping concentration of the YAG laser crystal 4 is 1 at.%, the size is phi 4mm × 10mm, Nd: both ends of the YAG laser crystal 4 are vapor-plated with 808nm antireflection films and 1064nm antireflection films. Nd: the YAG laser crystal 4 converts the laser light of 808nm wavelength into 1064nm wavelength by amplification of the excitation radiation.
Both ends of the acousto-optic Q-switching device 5 are plated with 1064nm antireflection films, and the transmittances of the 808nm antireflection film and the 1064nm antireflection film are greater than 99.8%. Pulse laser with a certain repetition frequency can be formed through the acousto-optic Q-switching device 5.
One end of the laser resonant cavity rear cavity mirror 7 is plated with a 808nm antireflection film, and the other end of the laser resonant cavity rear cavity mirror 7 is simultaneously plated with a 1064nm high-reflection film and a 808nm high-transmission film in a vapor deposition manner; the transmittance of the 808nm antireflection film is more than 99.8%, the reflectivity of the 1064nm high-reflection film is more than 99.8%, and the transmittance of the 808nm high-transmission film is more than 98%.
On one hand, the laser with the wavelength of 808nm can enter Nd as much as possible: YAG laser crystal 4 in the Nd: the YAG laser crystal 4 is amplified and converted into 1064nm laser through light stimulated radiation, and on the other hand, a 1064nm high-reflection film is plated, so that 1064nm light serving as an SPS pumping source can form laser oscillation of a sufficient cavity, SPS-Stokes laser can be generated as much as possible, and the efficiency of a laser is improved.
A high reflection film in the wavelength range of 1064nm-1090nm and a high transmission film in the wavelength range of 1090nm-1200nm are vapor-plated on the output mirror 8 of the laser resonant cavity; the reflectivity of the high-reflection film in the wavelength range of 1064nm-1090nm is more than 99.8%, and the transmittance of the high-transmission film in the wavelength range of 1090nm-1200nm is more than 80%.
In the laser resonant cavity, the coating of the output mirror 8 of the laser resonant cavity ensures that the pumping laser forms stable oscillation in the laser resonant cavity and prevents the occurrence of the scattering of the cascade excited electromagnetic coupler.
The rear cavity mirror 10 of the Stokes parametric oscillation cavity is evaporated with a high-reflection film within the wavelength range of 1000nm-1200nm, and the reflectivity of the high-reflection film within the wavelength range of 1000nm-1200nm is more than 99.8%.
The film coating of the Stokes parametric oscillation cavity rear cavity mirror 10 relates to the first-order SPS-Stokes laser Gao-inversions with different wavelengths generated by scattering of the excited electromagnetic coupler, and ensures the high intensity of the first-order SPS-Stokes laser in the Stokes parametric oscillation cavity.
As shown in fig. 3, a high-reflection film in the wavelength range of 1050nm to 1090nm, a partially transparent film in the wavelength range of 1100nm to 1130nm, and a high-transparent film in the wavelength range of 1140nm to 1220nm are evaporated on the output mirror 11 of the stokes parameter oscillation cavity; the reflectivity of the high-reflection film in the wavelength range of 1050nm to 1090nm is more than 99.5 percent; the transmittance of part of the permeable membrane in the wavelength range of 1100nm-1130nm is 5% -30%; the transmittance of the high-transmittance film in the wavelength range of 1140nm-1220nm is more than 80 percent.
In the Stokes parametric oscillation cavity, the film coating design of an output mirror 11 of the Stokes parametric oscillation cavity enables the cascade stimulated Raman scattering in the Stokes parametric oscillation cavity to be inhibited, and only first-order SRS-Stokes laser is generated in the Stokes parametric oscillation cavity.
The Stokes parametric oscillation cavity rear cavity mirror 10 and the Stokes parametric oscillation cavity output mirror 11 are both arranged on a rotary displacement platform 14, the angle between the Stokes parametric oscillation cavity and the laser resonant cavity can be adjusted, and stimulated Raman lasers with different wavelengths are output in a tuning mode through the change of the angle.
The size of the nonlinear crystal 9 is 4mm multiplied by 30mm, both ends of the nonlinear crystal 9 are evaporated with antireflection films within the wavelength range of 1000nm to 1200nm, and the transmittance of the antireflection films within the wavelength range of 1000nm to 1200nm is more than 99.8%.
Nd: YAG laser crystal 4, acousto-optic crystal 5 and nonlinear crystal 9 are wrapped by indium foil and then put into a red copper block, and water is introduced for cooling, and the cooling temperature is controlled at 20 ℃.
Example 2
The working method of the tunable laser for cascade excited electromagnetic coupling scattering and excited raman scattering provided in embodiment 1 is as follows:
(1) the diode laser 1 outputs continuous laser with the wavelength of 808nm, and the optical coupling lens 3 couples the continuous laser into the laser resonant cavity; in the laser resonator, through Nd: the YAG laser crystal 4 performs the stimulated radiation amplification function and the frequency adjustment of the acousto-optic Q-switch device 5, pump laser with the wavelength of 1064nm is output, and the pump laser with the wavelength of 1064nm outputs pump laser in the vertical polarization direction through the polarization beam splitter prism 6;
(2) after the nonlinear crystal 9 is acted by the pump laser, because the stimulated electromagnetic coupling scattering takes precedence over the stimulated Raman scattering, the 1064nm pulse pump laser firstly generates the stimulated electromagnetic coupling scattering in the laser resonant cavity to generate a first-order SPS-Stokes laser;
(3) the first-order SPS-Stokes laser is used as pump laser to act on the nonlinear crystal 9, and stimulated Raman scattering is generated in the direction of the Stokes parametric oscillation cavity to generate first-order SRS-Stokes laser;
(4) the output mirror 11 of the Stokes parametric oscillation cavity outputs cascade first-order SPS-Stokes laser and first-order SRS-Stokes laser, and the tunable output of the stimulated Raman laser is realized by tuning the angle between the Stokes parametric oscillation cavity and the laser resonant cavity.
In order to obtain the relation between the laser wavelength and the angle output by the tunable laser, a rotary displacement platform is adjusted, the angle of each rotation is 0.1 degrees, the angle is changed from 1.5 degrees to 5.5 degrees, the light output by a Stokes parametric oscillation cavity output mirror separates SPS-Stokes from SRS-Stokes through a dichroic mirror, and a spectrometer records the wavelength of first-order SRS-Stokes laser light output at each angle and the wavelength of the first-order SPS-Stokes laser light, so that the laser wavelength ranges of the first-order SRS-Stokes laser light are 1107.7 nm-1108.3 nm, 1109.8 nm-1112.7 nm, 1114.3 nm-1115.2 nm and 1117.8 nm-1221.1 nm as shown in figure 4; the wavelength ranges of the obtained first-order SPS-Stokes laser are 1075.7 nm-1075.8 nm, 1078.1 nm-1080.4 nm, 1081.8 nm-1082.2 nm and 1084.8 nm-1088.3 nm as shown in figure 2.
In order to obtain the difference of the output power at different wavelengths, the power of the output laser light at different wavelengths was recorded by a power meter at a light source power of 7.9W, and as a result, the tunable laser obtained the highest output power at a wavelength of 1118.6nm as shown in fig. 5.
In order to obtain the maximum output power of the tunable laser, the output wavelength of the fixed laser is 1118.6nm, the input-output relation of the power is obtained by adjusting the input power of the laser, as shown in fig. 6, the laser power output of 0.97W is obtained at the input pump power of 7.9W, and the conversion efficiency is 12.3%.
Example 3
The tunable laser for cascade excited electromagnetic couple scattering and excited raman scattering provided in embodiment 1 is characterized in that:
in this embodiment, the nonlinear crystal 9 is made of potassium titanyl arsenate (KTA), and the angle between the stokes parameter oscillation cavity and the laser resonant cavity is 1.8-7 °. The output first-order SRS-Stokes laser wavelength ranges from 1106.1nm to 1107.1nm, 1107.5nm to 1109.2nm, 1110.6nm to 1111.9nm, 1113.9nm to 1114.1nm and 1115.2nm to 1116.6 nm. The maximum power is at 1116.1nm wavelength.
Example 4
The tunable laser for cascade excited electromagnetic couple scattering and excited raman scattering provided in embodiment 1 is characterized in that:
in this example, the nonlinear crystal 9 is lithium niobate (LiNbO)3) The angle between the Stokes parametric oscillation cavity and the laser resonant cavity is 1-3 degrees.
Example 5
The tunable laser for cascade excited electromagnetic couple scattering and excited raman scattering provided in embodiment 1 is characterized in that:
in this embodiment, the nonlinear crystal 9 is made of potassium titanyl phosphate (KTP), and the angle between the stokes parameter oscillation cavity and the laser resonant cavity is 1.2 ° to 6.5 °.
Claims (10)
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| US6697186B2 (en) * | 2000-08-30 | 2004-02-24 | Riken | Method and apparatus for generating tera-hertz wave |
| CN101592845A (en) * | 2009-07-01 | 2009-12-02 | 天津大学 | Dual-wavelength tunable inner cavity tera-hertz parametric oscillator and using method thereof |
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| CN105048280A (en) * | 2015-08-06 | 2015-11-11 | 山东大学 | Stokes light source based on kalium titanyl arsenate crystal and working method and application of stokes light source |
| CN106019765A (en) * | 2016-07-31 | 2016-10-12 | 山东大学 | Terahertz parameter source coupling structure and working method thereof |
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| US6697186B2 (en) * | 2000-08-30 | 2004-02-24 | Riken | Method and apparatus for generating tera-hertz wave |
| CN101592845A (en) * | 2009-07-01 | 2009-12-02 | 天津大学 | Dual-wavelength tunable inner cavity tera-hertz parametric oscillator and using method thereof |
| CN105048280A (en) * | 2015-08-06 | 2015-11-11 | 山东大学 | Stokes light source based on kalium titanyl arsenate crystal and working method and application of stokes light source |
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