CN100458407C - Solid double-wavelength detecting laser radar - Google Patents

Abstract

A detecting laser radar in total solid type with double wavelength is prepared as forming said radar by 1064nm internal cavity optical parametric oscillator and 1064nm internal cavity sum frequency generator, utilizing LD1 side pumping Nd: YAG crystal and LD2 side pumping Nd: YAG crystal to generate 1064 and 1319nm laser, modulating generated laser by acousto-optic switch to raise peak value power, carrying out sum frequency of two waves in sum frequency cavity to output 589nm laser, using 1064nm laser remained after sum frequency to output 3-5 micron m intermediate infrared light source via said oscillator .

Description

All-solid-state dual-wavelength detection lidar

technical field

The invention relates to a dual-wavelength detection laser radar, in particular to an all-solid-state dual-wavelength detection laser radar, which belongs to the technical field of frequency conversion.

Background technique

Infrared light has three main transmission windows in the atmosphere: 1-3 μm, 3-5 μm, and 8-12 μm, among which the 3-5 μm band is the infrared window with the smallest attenuation, which has strong penetrating power for fog, smoke, etc. The absorption of gas molecules and the scattering of suspended matter are small for the transmission on the plane. The response range of the infrared guided missile detector is in the 3-5 μm band, so the photoelectric countermeasures against the infrared seeker also urgently need a laser light source in this band. The military application of the 3-5μm band is more important, and the application prospects are mainly in two aspects: imaging laser radar and laser directional infrared interference. In the 3-5μm region, most important hydrocarbon gases and other toxic gas molecules have strong absorption characteristics, so mid-infrared coherent light sources have a wide range of civil value in the field of trace gas detection, such as: oil field exploitation, natural gas pipeline leakage detection, atmospheric Greenhouse gas detection, drug inspection, methane gas detection in coal mines, etc.

The sodium atomic layer is an atmospheric layer composed of metal sodium atoms at an altitude of about 80-110 km. In the past, research on this area could only be carried out by sounding rockets or satellites equipped with remote sensing devices or ground-based remote sensing devices. Aircraft and satellites could not approach the area. Perhaps the least understood region of Earth's atmosphere is this region. Since the high-altitude sodium layer is in the confluence region of the neutral atmosphere and the ionized atmosphere, it has various complex physical, chemical and dynamic interactions with other atoms, molecules, and ions in the atmosphere. The detection of lasers has become an important means of studying the middle and upper atmosphere. The sodium atomic layer has a strong reflection of the 589nm sodium yellow light. Therefore, the sodium yellow light can also be used as a beacon light to measure the distortion effect of laser atmospheric transmission. , in order to correct the laser.

Mid-infrared (3-5μm) laser technology is closely related to the development of nonlinear crystal materials. Since the late 1980s, with the rapid development of nonlinear crystal materials, many nonlinear crystal materials with excellent performance in the mid-infrared band have appeared, and people have begun to realize that optical parametric oscillation technology is an effective means to achieve mid-infrared laser output. KNbO ₃ , LNbO ₃ , KTP, KTA, AgGaS ₂ , AgGaSe ₂ and other crystals have been used to achieve laser output in the wavelength range of 3-5 μm or even longer through nonlinear frequency conversion technology. So far, the wavelength has been extended beyond 20 μm, especially the research of 3-5 μm and 8-12 μm is the most popular.

Contents of the invention

The purpose of the present invention is to use simultaneously output dual-wavelength all-solid-state lasers as a laser radar light source to form a dual-wavelength laser radar, thereby meeting the needs of atmospheric monitoring, military radar, etc. for mid-infrared laser wavelengths, and meeting the requirements of sodium Special requirements for atomic layer lidar.

The present invention adopts following technical scheme:

An all-solid-state dual-wavelength detection laser radar is characterized in that it includes a first plane mirror (M1), a first acousto-optic Q switch (Q1), a first semiconductor pump module (LD1), and a first The second plane mirror (M2), the third plane mirror (M3), the sum frequency crystal (KTP), the fourth plane mirror (M4), the parametric oscillator crystal (MgO:LN), the fifth plane mirror (M5), and the The second plane mirror (M2), the second semiconductor pump module (LD2), the second acousto-optic Q switch (Q2), and the sixth plane mirror (M6) on the road, wherein,

The first plane mirror (M1) is a 1064nm total reflection mirror;

The two ends of the first acousto-optic Q switch (Q1) are coated with 1064nm antireflection film;

The first semiconductor pump module (LD1) is equipped with a laser crystal for side pumping, and the two ends of the crystal are coated with 1064 antireflection film;

The second plane mirror (M2) is coated with 1319nm 45° high reflection film and double-ended 1064nm 45° high transmittance film;

The third plane mirror (M3) is coated with 1064nm and 1319nm double-ended high-transparency coatings, and 589nm high-reflection coatings;

1064nm, 1319nm, 589nm anti-reflection coatings are coated on both ends of the sum frequency crystal (KTP), and the crystal cutting angle is θ=62.4°, Φ=0°;

The fourth plane mirror (M4) is coated with 1.4～1.5μm, 1319nm high-reflection film, 1064nm double-ended high-transparency film, and 589nm high-transparency film;

The cutting angle of the parametric oscillating crystal (MgO:LN) is θ=48°, Φ=-90°, both ends are coated with 1064nm, 589nm high-transparency films and 3-5μm, 1.4-1.5μm high-transmission films;

The fifth plane mirror (M5) is CaF ₂ material, coated with 1064nm high reflection film, 589nm and 3-5μm high-transmission film and 1.4-1.5μm high-reflection film;

The second semiconductor pump module (LD2) is equipped with a laser crystal for side pumping, and the two ends of the crystal are coated with a 1319nm antireflection film;

The two ends of the second acousto-optic Q switch (Q2) are coated with 1319nm antireflection film;

The sixth plane mirror (M6) is coated with 1064nm antireflection coating and 1319nm total reflection coating.

The beneficial effects that the present invention has:

All-solid-state lasers are compact, durable, and cheap, and play a very important role in laser applications; at the same time, they can operate in various modes, such as continuous, pulsed, Q-switched, and mode-locked, and operate in quasi-continuous mode. The high peak power of the laser has obvious advantages in improving the pumping efficiency.

Using the optical nonlinear frequency change process such as sum frequency and optical parametric oscillation, the two mechanisms of mid-infrared wavelength and sodium layer fluorescence can be output simultaneously in one laser system, which can satisfy the operator with more flexible operability and has better military advantages. concealment.

Description of drawings

Fig. 1: System structural diagram of the present invention.

Detailed ways

The present invention utilizes a dual-wavelength all-solid-state laser output at the same time as a laser radar light source, integrates the two wavelengths into a laser radar by adopting some key technologies, and upgrades the original technology into a dual-wavelength laser radar. The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

The dual-wavelength laser light source of the present invention is mainly composed of two parts: a 1064nm inner cavity optical parametric oscillator and a 1319nm and 1064nm inner cavity sum frequency generator. Fig. 1 is the system structural diagram of the present invention, wherein, M1 and M5 form 1064nm laser resonant cavity, by the continuous 1064nm laser that LD1 side pumps Nd:YAG crystal generation, improve its peak power through the modulation of acousto-optic Q switch; Simultaneously, The 1319nm laser cavity is composed of M6 and M4, and the continuous 1319nm laser generated by the Nd:YAG crystal pumped by the side of LD2 increases the peak power through the modulation of the acousto-optic Q switch. The two waves are summed in the sum frequency cavity composed of M3, KTP and M4, and the 589nm laser is output from M5 through M4; the remaining 1064nm laser is passed through the optical parametric oscillator composed of M4, MgO:LN and M5 to generate 3~5μm mid-infrared light source, output from M5 mirror.

As shown in Figure 1, M1 is a 1064nm total reflection mirror; Q1 is an acousto-optic Q switch, coated with 1064 anti-reflection coating at both ends; LD1 is a semiconductor pump module, which is equipped with Nd:YAG crystal for side pumping, Coated with 1064 anti-reflective coating; M2 coated with 1319nm 45° high-reflection coating and double-ended 1064nm 45° high-transparency coating; M3 coated with 1064nm and 1319nm double-ended high-transmission coating, 589nm high-reflection coating; KTP crystal double-ended coated with 1064nm, 1319nm, 589nm anti-reflection coating, crystal cutting angle is θ=62.4°, Φ=0°; M4 plated 1.4～1.5μm, 1319nm high-reflection coating, 1064nm double-ended high-transparency coating, 589nm high-transparency coating; MgO:LN crystal cutting angle is θ=48°, Φ=-90°, both ends coated with 1064nm high-transparency film, 589nm and 3-5μm high-transmission film, 1.4-1.5μm high-transmission film; M5 is CaF ₂ material, coated with 1064nm high-reflection film, 589nm and 3-5μm high-transparency film 1.4-1.5μm high-reflection film. LD2 is a semiconductor pump module, which is equipped with a Nd:YAG crystal for side pumping. Both ends of the crystal are coated with a 1319nm anti-reflection coating; Q2 is an acousto-optic Q switch, and both ends are coated with a 1319nm anti-reflection coating; M6 is coated with a 1064nm anti-reflection coating And 1319nm full reflection film.

The infrared laser uses the Nd:YAG laser pumped by the semiconductor module 1 to emit the fundamental frequency light of 1064nm, which passes through the nonlinear crystal MgO:LN optical parametric oscillator to generate a laser beam with a wavelength of 3-5μm; the laser light source used to detect the sodium atomic layer , the fundamental frequency light 1064nm emitted by the Nd:YAG laser pumped by the semiconductor module 1 and the fundamental frequency light 1319nm emitted by the Nd:YAG laser pumped by the semiconductor module 2 are combined in a KTP crystal to generate a wavelength of 589nm A laser beam used to probe sodium atoms in the upper atmosphere. The invention satisfies the needs of atmospheric monitoring, military radar and sodium atomic layer laser through simultaneous output of mid-infrared laser wavelength and sodium layer fluorescence.

The dual-wavelength laser light source system of the present invention adopts all solid-state devices, controls the laser to operate in a quasi-continuous mode through an acousto-optic Q switch, and the repetition frequency is adjustable at 1-20 kHz, so as to make full use of the high peak power of the quasi-continuous mode. Improve the conversion efficiency of sum-frequency and optical parametric oscillation processes.

Claims (1)

1. solid double-wavelength detecting laser radar, it is characterized in that, comprise first level crossing (M1) that is successively set on the same light path, first acousto-optic Q-switching (Q1), first semiconductor pumping module (LD1), second level crossing (M2), the 3rd level crossing (M3), with frequency crystal KTP, the 4th level crossing (M4), parametric oscillation crystalline MgO: LN, the 5th level crossing (M5), also comprise second level crossing (M2) that is successively set on the same light path, second semiconductor pumping module (LD2), second acousto-optic Q-switching (Q2), the 6th level crossing (M6), wherein

Described first level crossing (M1) is the 1064nm total reflective mirror;

Described first acousto-optic Q-switching (Q1) two ends plating 1064nm anti-reflection film;

Be equipped with the laser crystal that carries out profile pump in described first semiconductor pumping module (LD1), the crystal two ends are coated with 1064 anti-reflection films;

45 ° of high transmittance films of 1319nm45 ° of high-reflecting film of described second level crossing (M2) plating and both-end 1064nm;

Described the 3rd level crossing (M3) plating 1064nm and 1319nm both-end high transmittance film, the 589nm high-reflecting film;

Described and the 1064nm of crystal KTP both-end plating frequently, 1319nm, the 589nm anti-reflection film, the crystal-cut angle is θ=62.4 °, Φ=0 °;

Described the 4th level crossing (M4) plating 1.4～1.5 μ m, 1319nm high-reflecting film, 1064nm both-end high transmittance film, 589nm high transmittance film;

Described parametric oscillation crystalline MgO: the cutting angle of LN is θ=48 °, Φ=-90 °, both-end plating 1064nm, 589nm high transmittance film and 3～5 μ m, 1.4～1.5 μ m high transmittance films;

Described the 5th level crossing (M5) is a calcium fluoride material, plating 1064nm high-reflecting film, 589nm and 3～5 μ m high transmittance films and 1.4～1.5 μ m high-reflecting films;

Be equipped with the laser crystal that carries out profile pump in described second semiconductor pumping module (LD2), the crystal two ends are coated with the 1319nm anti-reflection film;

Described second acousto-optic Q-switching (Q2) two ends plating 1319nm anti-reflection film;

The 6th level crossing (M6) plating 1064nm anti-reflection film and the 1319nm film that is all-trans.