Dual-wavelength laser polarization splitting multiplexing emission system, method and application

Abstract

The invention discloses a dual-wavelength laser polarization splitting multiplexing emission system and method and application, the system comprises a Rayleigh Raman laser emission module, a resonance fluorescence laser emission module and a laser emission switching module, the Rayleigh Raman laser emission module emits a 532 nm laser beam, the resonance fluorescence laser emission module emits a 589 nm laser beam, and the laser emission switching module is connected with the Rayleigh Raman laser emission module and the resonance fluorescence laser emission module. The Rayleigh Raman laser emission module and the resonance fluorescence laser emission module share one high-power Nd: YAG laser; the laser emission switching module comprises a high-power PBS and an electrically-controlled rotary high-damage-threshold half-wave plate, the electrically-controlled rotary high-damage-threshold half-wave plate is used for controlling the polarization angle of an emitted laser beam, and the high-power PBS is used for controlling the emission direction of the laser beam. The dual-wavelength laser polarization splitting multiplexing emission technology provided by the invention can well meet the high specification requirements of the full-upper atmosphere temperature measurement laser radar on dual wavelength, high power and the like of laser emission, and is applied to the full-upper atmosphere temperature measurement laser radar.

Description

Technical Field

[0001] The present invention relates to the technical field of atmospheric lidar detection, in particular to a dual-wavelength laser polarization splitting multiplexing emission system, method and application. Background Art

[0002] The Earth's atmosphere from near the ground to 110 km mainly includes the troposphere, stratosphere, mesosphere and lower thermosphere. The variation of the vertical structure of the atmospheric temperature is a comprehensive manifestation of the atmospheric dynamic-radiation-chemical coupling process, which directly affects the global energy balance and cross-sphere material transport. Weather phenomena closely related to human daily life, such as rain, snow and most clouds, mainly occur in the troposphere. The rapid development of aerospace, modern communication and navigation technologies has continuously expanded the scope of human activities into the middle and upper atmospheric spheres above the troposphere. There are significant interactions between different atmospheric spheres. Pollutants crossing the tropopause into the stratosphere are an important cause of ozone depletion and can also exacerbate the tropospheric greenhouse effect. The interaction between planetary waves originating from the troposphere and the stratospheric mean flow can produce sudden stratospheric warming, which can cause the reversal of the background atmospheric circulation in the middle and upper atmosphere. Ionospheric changes can lead to changes in the composition, temperature and wind field of the neutral atmosphere, resulting in the redistribution of global atmospheric energy. Therefore, taking the entire atmospheric sphere as a whole and carrying out high-precision, high spatio-temporal resolution detection of the vertical profile of the temperature of the whole high altitude (from near the ground to 110 km) atmosphere has important scientific significance and application value for atmospheric science and near-space environmental monitoring, and is a hot topic in scientific research.

[0003] As an accurate active remote sensing detection means, lidar can conduct real-time detection of atmospheric temperature in different layers. From the lower layer to the upper layer, pure rotational Raman temperature measurement technology, Rayleigh temperature measurement technology, resonance fluorescence Doppler temperature measurement technology, etc. can be used respectively. However, the coverage height range of a single technology is limited. To achieve the through-type detection of atmospheric temperature from near the ground to 110 km, it is necessary to integrate lidar technologies with different detection principles. Different atmospheric scattering mechanisms can be used to achieve temperature detection of atmospheric layers at different heights. However, the coverage height range of a single lidar temperature measurement technology is limited. Different detection technologies are required at different heights, and there are discontinuities or deviations in the data of different detection technologies, which requires effective calibration and multi-source data fusion. To obtain the vertical profile of atmospheric temperature from near the ground to 110 km, it is necessary to carry out research on lidar full-layer temperature measurement technology based on multi-scattering physical systems. This lidar mainly uses 532 nm laser to conduct lidar temperature detection of the atmosphere from near the ground to 80 km based on pure rotational Raman and Rayleigh temperature measurement systems, and uses 589 nm to conduct lidar temperature detection of the atmosphere from 80 km to 110 km based on sodium fluorescence Doppler temperature measurement system. This requires that the lidar full-layer temperature measurement technology incorporating multi-scattering physical systems needs to emit two or more laser wavelengths, and a single laser wavelength is difficult to meet the technical requirements of the full-layer temperature measurement lidar. In the existing technology, there are problems such as generally low energy of the two laser emissions and low laser energy utilization rate in the two-time frequency doubling and residual light multiplexing technology. Summary of the Invention

[0004] In order to overcome the above problems existing in the prior art, the present invention proposes a dual-wavelength laser polarization beam splitting multiplexing emission system, method and application.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a dual-wavelength laser polarization beam splitting multiplexing emission system, including a Rayleigh Raman laser emission module, a resonance fluorescence laser emission module, and a laser emission switching module. The Rayleigh Raman laser emission module emits a 532 nm laser beam, and the resonance fluorescence laser emission module emits a 589 nm laser beam. The Rayleigh Raman laser emission module and the resonance fluorescence laser emission module share a high-power Nd:YAG laser. The laser emission switching module includes a high-damage-threshold PBS and an electrically controlled rotating high-damage-threshold half-wave plate. The electrically controlled rotating high-damage-threshold half-wave plate is used to control the polarization angle of the emitted laser beam, and the high-damage-threshold PBS is used to control the emission direction of the laser beam.

[0006] In the above-mentioned dual-wavelength laser polarization beam splitting multiplexing emission system, the Rayleigh Raman laser emission module includes a 532 nm pulsed high-power Nd:YAG laser with seed injection and a laser reflector.

[0007] The above-mentioned dual-wavelength laser polarization beam splitting and multiplexing emission system, wherein the resonance fluorescence laser emission module includes a 532 nm pulsed high-power Nd:YAG laser with seed injection, a Doppler-free saturated absorption spectroscopy frequency locking device, a fully solid-state 589 nm continuous narrow-linewidth Toptica seed laser, an AOM acousto-optic frequency shift module, a wavemeter, an optical fiber coupler, a laser beam splitter, a pulsed dye amplifier, and a laser mirror.

[0008] A dual-wavelength laser polarization beam splitting and multiplexing emission method, based on the above-mentioned dual-wavelength laser polarization beam splitting and multiplexing emission system, specifically includes: adjusting the angle of the electrically controlled rotating high-damage-threshold half-wave plate to control the polarization angle of the 532 nm output laser beam, using a high-power PBS to control the emission direction of the 532 nm laser beam. When the polarization direction of the 532 nm laser is reflected and emitted by the PBS, it provides emission laser for the Rayleigh Raman module. When the angle of the electrically controlled rotating high-damage-threshold half-wave plate is adjusted so that the laser polarization direction continues to rotate 90 degrees, the 532 nm laser beam passes through the PBS crystal and enters the PDA amplifier, providing pump laser for the resonance fluorescence module. At this time, the laser emission is switched to 589 nm.

[0009] The above-mentioned dual-wavelength laser polarization beam splitting and multiplexing emission method, through the acquisition control software, collaboratively controls the rotation angle of the electrically controlled rotating high-damage-threshold half-wave plate and the data acquisition process.

[0010] An application of a dual-wavelength laser polarization beam splitting and multiplexing emission system, based on the above-mentioned dual-wavelength laser polarization beam splitting and multiplexing emission system, or using the above-mentioned dual-wavelength laser polarization beam splitting and multiplexing emission method, is applied to a full upper atmosphere temperature measurement lidar.

[0011] The beneficial effects of the present invention are as follows. The present invention solves the problems of insufficient laser output energy, low laser energy utilization rate, and multi-wavelength switching of high-power laser emission. The first beam of laser and the second beam of laser in the present invention are each emitted in the maximum power state after passing through the polarization beam splitting crystal. The full upper atmosphere temperature measurement lidar has very high requirements for high-power laser emission. Because the measurement height range is large, the subsequent problem is the weak signal level. Therefore, the dual-wavelength laser polarization beam splitting and multiplexing emission technology proposed by the present invention can well meet the high-standard requirements of the full upper atmosphere temperature measurement lidar for dual-wavelength (589 nm, 532 nm), high-power laser emission. Brief Description of the Drawings

[0012] Figure 1 It is a schematic diagram of the emission system of the present invention. Detailed Embodiments

[0013] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0014] In order to achieve through-type and seamless detection of the vertical profile of the upper atmosphere temperature, this embodiment discloses a dual-wavelength laser polarization splitting multiplexing transmission system, such as Figure 1 As shown, it includes Rayleigh Raman laser emission module (532 nm), resonant fluorescence laser emission module (589 nm) and laser emission switching module, which will generate 532 nm and 589 nm dual laser beams. The laser emission switching module mainly includes high-power PBS and electrically controlled rotating high damage threshold half-wave plate, Rayleigh Raman laser emission module mainly consists of 532 nm pulse high-power Nd:YAG laser with seed injection and laser reflector; resonant fluorescence laser emission module mainly consists of 532 nm pulse high-power Nd:YAG laser with seed injection, Doppler-free saturated absorption fluorescence spectrum frequency locking device, all-solid-state 589 nm continuous narrow linewidth Toptica seed laser, AOM (Acoustic Optic Modulator) acousto-optic frequency shifting module, wavelength meter, fiber coupler, laser beam splitter, pulse dye amplifier (Pulsed Dye Amplifier) ​​and laser reflector. The Rayleigh Raman and resonance fluorescence laser emission modules share a high-power Nd:YAG laser. When working, the laser emission switching module realizes polarization splitting multiplexing emission of the 50 Hz, 18 W high-power 532 nm pulse laser emitted by the Nd:YAG laser.

[0015] Based on the above-mentioned transmitting system, the present invention also discloses a dual-wavelength laser polarization splitting multiplexing transmitting method, which uses an electric rotating mirror frame to adjust the angle of a high damage threshold half-wave plate, thereby controlling the polarization angle of a 532 nm outgoing laser beam, and then uses a high-power PBS to control the emission direction of the 532 nm laser beam. When the polarization direction of the 532 nm laser is reflected and emitted by the PBS, it provides an emission laser for the Rayleigh Raman module. When the angle of the half-glass is controlled so that the laser polarization direction continues to rotate 90 degrees, the 532 nm laser beam will pass through the PBS crystal into the PDA amplifier, providing a pump laser for the resonance fluorescence module, and then switch to 589 nm laser emission. The switching output of the maximum laser power of the Rayleigh Raman emission module and the resonance fluorescence emission module is realized through the above-mentioned polarization splitting multiplexing process, and the rotation angle and data acquisition process of the electric rotating mirror frame are coordinated controlled by the acquisition control software to realize the high-time resolution detection of the temperature of the entire upper atmosphere.

[0016] This embodiment mainly aims to solve the problem that the lidar full-altitude temperature measurement technology incorporating a multi-scattering physical system requires the emission of two or even more laser wavelengths, and a single laser wavelength is difficult to meet the technical requirements of the full-altitude temperature measurement lidar. It also solves the problem that the energy of the two laser emissions in the existing two-time frequency doubling and residual light multiplexing technology is generally low and the laser energy utilization rate is not high.

[0017] The dual-wavelength laser polarization beam splitting and multiplexing emission technology proposed in this embodiment can well solve the problems of insufficient laser output energy and low laser energy utilization rate. The first laser beam and the second laser beam emitted by the dual-wavelength polarization beam splitting and multiplexing emission technology in this embodiment are each emitted in the maximum power state after passing through the polarization beam splitting crystal. The full-altitude atmospheric temperature measurement lidar has very high requirements for high-power laser emission. Because the measurement height range is large, the consequent problem is weak signal level. Therefore, the dual-wavelength laser polarization beam splitting and multiplexing emission technology proposed in this embodiment can well meet the high-specification requirements of the full-altitude atmospheric temperature measurement lidar for the dual wavelengths (589nm, 532nm) and high power of laser emission, and can be applied to the full-altitude atmospheric temperature measurement lidar.

[0018] The above embodiments are only exemplary embodiments of the present invention and are not used to limit the present invention. Those skilled in the art can make various modifications or equivalent replacements within the essence and protection scope of the present invention, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of the present invention.

Claims

1. A dual-wavelength laser polarization beam splitting and multiplexing emission system, characterized in that, It includes a Rayleigh Raman laser emission module, a resonance fluorescence laser emission module, and a laser emission switching module, wherein the Rayleigh Raman laser emission module emits a 532 nm laser beam, the resonance fluorescence laser emission module emits a 589 nm laser beam, and the Rayleigh Raman laser emission module and the resonance fluorescence laser emission module share a high-power Nd:YAG laser; The laser emission switching module includes a high-power PBS and an electrically controlled rotating high damage threshold half-wave plate, wherein the electrically controlled rotating high damage threshold half-wave plate is used to control the polarization angle of the emitted laser beam, and the high-power PBS is used to control the emission direction of the laser beam.

2. The dual-wavelength laser polarization beam combining and multiplexing emission system according to claim 1, wherein The Rayleigh Raman laser emission module comprises a 532 nm pulsed high-power Nd:YAG laser with seed injection and a laser reflector.

3. A dual-wavelength laser polarization beam splitting and multiplexing emission system according to claim 1, wherein The resonance fluorescence laser emission module includes a 532 nm pulsed high-power Nd:YAG laser with seed injection, a Doppler-free saturated absorption spectrum frequency locking device, an all-solid-state 589 nm continuous narrow-linewidth Toptica seed laser, an AOM acousto-optic frequency shifting module, a wavelength meter, an optical fiber coupler, a laser beam splitter, a pulse dye amplifier, and a laser reflector.

4. A dual-wavelength laser polarization beam splitting and multiplexing emission method, characterized in that A dual-wavelength laser polarization splitting multiplexing emission system based on any one of claims 1 to 3, specifically comprising: adjusting the angle of the electrically controlled rotating high damage threshold half-wave plate, controlling the polarization angle of the 532 nm outgoing laser beam, using a high-power PBS to control the emission direction of the 532 nm laser beam, when the polarization direction of the 532 nm laser is reflected and emitted by the PBS, providing an emission laser for the Rayleigh Raman module, when the electrically controlled rotating angle of the high damage threshold half-wave plate causes the laser polarization direction to continue to rotate 90 degrees, when the 532 nm laser beam passes through the PBS crystal and enters the PDA amplifier, providing a pump laser for the resonant fluorescence module, and at this time switching to 589 nm laser emission.

5. A dual-wavelength laser polarization beam splitting and multiplexing emission method according to claim 3, wherein The rotation angle and data acquisition process of the electrically controlled rotating high damage threshold half-wave plate are collaboratively controlled through the acquisition control software.

6. Application of a dual-wavelength laser polarization beam splitting and multiplexing emission system, characterized in that, Based on a dual-wavelength laser polarization splitting multiplexing transmission system as described in any one of claims 1-3, or using a dual-wavelength laser polarization splitting multiplexing transmission method as described in claims 4-5, it is applied to a full-high-level atmospheric temperature measurement laser radar.

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