A dual-wavelength tunable laser device

Abstract

The present invention relates to a dual-wavelength tunable laser device, and belongs to the field of laser technology. By using the same pump source and two parametric crystals with different cutting angles, two wavelength laser outputs are simultaneously obtained in an optical parametric resonant cavity, and the output laser center wavelengths can be tuned separately by changing the angle of the pump light incident on the crystal end face. In particular, by adjusting the angle between the pump light and the crystal to a specific angle, lasers with center wavelengths of 486.1 nanometers and 518.3 nanometers can be obtained, which are respectively aligned with the solar Fraunhofer dark line H‑β line and Mg line in the blue-green band. The dual-wavelength laser device of the present invention has a compact structure, and the method for generating a dual-wavelength tunable laser can be widely used in laser radar, laser communication, spectral analysis and other fields.

Description

Technical Field

[0001] The invention relates to all-solid-state laser technology, in particular to a dual-wavelength tunable laser device. Background Art

[0002] In the field of laser communications, increasing the number of wavelengths of the emitting light source can achieve wavelength division multiplexing and increase the communication rate. In the field of lidar detection, the use of multiple emission wavelengths can be used for multi-spectral detection, obtaining characteristic information of different bands, and realizing more accurate detection and identification of targets. At present, in most application systems, the light source is generally a single wavelength and is not tunable. To achieve the simultaneous emission of multiple wavelengths, multiple lasers are required. The lasers output by multiple lasers are not on the same optical axis. In the application of co-linear emission, beam combining is required, which increases the system complexity and volume power consumption requirements. In addition, the light emitted by multiple lasers is not coherent and cannot meet the measurement correlation requirements.

[0003] The invention patent with application number 201710508429.5 and the name of “dual-wavelength laser” uses a self-doubling crystal to emit two wavelengths of fundamental frequency light and doubled frequency light. The emitted laser wavelength is determined by the emission peak of the laser crystal and cannot be tunable.

[0004] Patent number ZL200510014738.4, named "Multi-wavelength simultaneous output of all-solid-state tunable laser light source", uses a two-stage pump source and an optical parametric oscillator to obtain 0.7-5μm laser output. It cannot cover the light source requirements of the blue-green light band, and the technology using two-stage pumping is also relatively complicated. Summary of the invention

[0005] The present invention aims to solve the problem that two tunable lasers cannot be output simultaneously in the same laser, and provides a dual-wavelength tunable laser device, which uses only one pump source and realizes simultaneous tuning of two output laser wavelengths through two mutually perpendicular polarized light pumping modes, and the output laser optical axes are the same.

[0006] To achieve the above-mentioned purpose, the present invention provides a dual-wavelength tunable laser device, the basic principle of which is: the pump laser output by the pump laser is divided into horizontally polarized pump light and vertically polarized pump light by a polarization beam splitter prism, and two parametric crystals whose optical axes are perpendicular to each other are pumped from both sides of an optical parametric oscillator to generate two signal lights of different wavelengths, and the wavelengths of the two signal light lasers are tuned by adjusting the angles between the pump light and the parametric crystals. The two signal lights are coaxially output through the output mirror of the optical parametric oscillator, and the remaining horizontally polarized pump light and vertically polarized pump light can be transmitted and reflected by the polarization beam splitter prism respectively to avoid returning to the pump laser and causing damage to the pump laser.

[0007] The technical solution of the present invention is as follows:

[0008] A dual-wavelength tunable laser device comprises a pump laser, a half-wave plate, a first polarization beam splitter prism, an OPO total reflection mirror, a first parametric crystal, a second parametric crystal, an OPO output mirror, a beam splitter, a reflection mirror and a second polarization beam splitter prism.

[0009] The laser output by the pump laser is linearly polarized. The pump light is rotated to a polarization direction of 45° with the optical axis by a half-wave plate, and then is divided into a transmitted horizontally polarized pump light and a reflected vertically polarized pump light by a first polarization beam splitter prism.

[0010] The OPO total reflection mirror, the first parameter crystal, the second parameter crystal and the OPO output mirror form an optical parametric oscillator.

[0011] The OPO total reflection mirror is plated with a pump light anti-reflection film and first signal light and second signal light total reflection films.

[0012] The crystal optical axis directions of the first parametric crystal and the second parametric crystal are perpendicular to each other. The two crystals can be placed independently of each other or become bonded crystals after surface treatment. Pump light, first signal light and second signal light anti-reflection films are plated on both ends. The placement angle of the first parametric crystal and the second parametric crystal relative to the optical path is adjustable.

[0013] The OPO output mirror is plated with a pump light anti-reflection film and a first signal light and a second signal light partially transparent partial reflection film, and the transmittance of the first signal light and the second signal light is 20% to 50%.

[0014] The beam splitter is plated with a pump light total reflection film and first signal light and second signal light anti-reflection films, and its placement angle relative to the optical path is adjustable.

[0015] The horizontally polarized pump light is pumped by the OPO total reflection mirror to the first parametric crystal to generate the first signal light, and the remaining horizontally polarized pump light is transmitted by the second parametric crystal and the OPO output mirror, and then reflected by the beam splitter to the second polarization beam splitter prism and transmitted by the prism;

[0016] The vertically polarized pump light is reflected by the reflector, the second polarization beam splitter prism and the beam splitter in sequence, and then pumps the second parameter crystal through the OPO output mirror to generate the second signal light, and the remaining vertically polarized pump light is transmitted to the first polarization beam splitter prism through the first parameter crystal and the OPO total reflection mirror and reflected by the prism;

[0017] The first signal light and the second signal light are oscillated and amplified in the optical parametric oscillator, and are transmitted and outputted through the OPO output mirror and the beam splitter.

[0018] The present invention has the following advantages:

[0019] 1. The output laser has two wavelengths, and the wavelengths can be tuned separately. The tuned wavelengths can cover the blue-green laser band. Two wavelengths are selected, namely 486.1nm blue light and 518.3nm green light, which are respectively aimed at the solar Fraunhofer dark line H-β line and Mg line in the blue-green band, respectively. This can simultaneously meet the penetration ability requirements of the laser application system under different water quality conditions. In addition, the dark line wavelength laser source is used in conjunction with a narrow-band filter device, which can effectively reduce the solar background radiation received by the detector, improve the signal-to-noise ratio of the receiving system, and achieve reliable detection;

[0020] 2. The pump laser is polarized and split to realize a double-end-pumped optical parametric oscillator, which has high conversion efficiency, simple and compact structure and is widely used in laser radar, laser communication, spectral analysis and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the optical path of the dual-wavelength tunable laser device of the present invention.

[0022] Figure 2 It is a spectrum diagram of the output transmitted through the OPO output mirror and the spectroscope of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the embodiments and drawings, but the protection scope of the present invention should not be limited thereto.

[0024] Figure 1 It is a schematic diagram of the principle of the dual-wavelength tunable laser device of the present invention. As can be seen from the figure, a dual-wavelength tunable laser includes a pump laser 1, a half-wave plate 2, a first polarization beam splitter prism 3, an OPO total reflection mirror 4, a first parametric crystal 5, a second parametric crystal 6, an OPO output mirror 7, a beam splitter 8, a reflection mirror 9 and a second polarization beam splitter prism 10.

[0025] The pump laser 1 is a Nd:YAG triple frequency pulse laser, the output laser is linearly polarized light, the wavelength is 355nm, the pulse repetition frequency is 100Hz, the pulse width is about 5ns, and the single pulse energy is 4mJ;

[0026] The half-wave plate 2 is a 355nm quartz half-wave plate coated with a 355nm anti-reflection film;

[0027] The first polarization beam splitter prism 3 is a 355nm polarization beam splitter prism, with a transmittance of 355nm horizontal polarized light greater than 95%, and a reflectance of 355nm vertical polarized light greater than 99%;

[0028] The OPO total reflection mirror 4 is coated with a 355nm anti-reflection film on both sides, and a 400nm-600nm broadband total reflection film is coated on the side facing the first parameter crystal 5;

[0029] The first parameter crystal 5 is a barium borate BBO crystal, with a cutting angle of θ=27°, Φ=90°, and 355nm and 400nm-600nm anti-reflection films coated on both ends;

[0030] The second parameter crystal 6 is a barium borate BBO crystal, with a cutting angle of θ=30°, Φ=90°, and 355nm and 400nm-600nm anti-reflection films coated on both ends;

[0031] The crystal optical axis directions of the first parametric crystal 5 and the second parametric crystal 6 are perpendicular to each other;

[0032] The OPO output mirror 7 is coated with a 355nm antireflection film and a 400nm-600nm partially transparent and partially reflective film, and the transmittance of 400nm-600nm is 30%;

[0033] The beam splitter 8 is coated with a 45° 355nm total reflection film and a 400nm-600nm anti-reflection film;

[0034] The 355nm laser output by the pump laser 1 is linearly polarized. The 355nm pump light passes through the half-wave plate 2 to rotate its polarization direction to 45° with the optical axis, and then passes through the first polarization beam splitter prism 3 to be divided into a transmitted horizontally polarized pump light and a reflected vertically polarized pump light.

[0035] The horizontally polarized pump light is pumped by the first parametric crystal 5 through the OPO total reflector 4 to generate 453nm signal light, and the remaining 355nm horizontally polarized pump light is transmitted through the second parametric crystal 6 and the OPO output mirror 7, and then reflected by the beam splitter 9 to the second polarization beam splitter prism 10 and transmitted through the prism;

[0036] The vertically polarized pump light is reflected by the reflector 9, the second polarization beam splitter prism 10 and the beam splitter 8 in sequence, and then pumps the second parameter crystal 6 through the OPO output mirror 7 to generate 497nm signal light. The remaining 355nm vertically polarized pump light is transmitted through the first parameter crystal 5 and the OPO total reflection mirror 4 to the first polarization beam splitter prism 3 and reflected by the prism.

[0037] The 453nm signal light and the 497nm signal light are oscillated and amplified in the optical parametric oscillator, and are transmitted and output through the OPO output mirror and the spectroscope. The output spectrum is as follows: Figure 2 As shown, by adjusting the angle between the first parametric crystal 5, the second parametric crystal 6 and the beam splitter 8 relative to the optical path, the two output wavelengths can be adjusted according to application requirements.

[0038] The above embodiments are only for illustrating the technical features of the present invention and should not be used to limit the protection scope of the present invention. Any modification or replacement that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A dual-wavelength tunable laser device, characterized in that: It comprises a pump laser (1), a half-wave plate (2), a first polarization beam splitter prism (3), an OPO total reflection mirror (4), a first parametric crystal (5) and a second parametric crystal (6) whose crystal optical axes are perpendicular to each other, an OPO output mirror (7), a beam splitter (8), a reflection mirror (9) and a second polarization beam splitter prism (10); The pump light output by the pump laser (1) is linearly polarized at 45 degrees after passing through the half-wave plate (2), and is then divided into transmitted horizontally polarized pump light and reflected vertically polarized pump light by the first polarization beam splitter (3); Along the transmission direction of the horizontally polarized pump light, the OPO total reflection mirror (4), the first parametric crystal (5), the second parametric crystal (6) and the OPO output mirror (7) are arranged in sequence. The horizontally polarized pump light pumps the first parametric crystal (5) to generate a parametric transformation to generate a first signal light. The first signal light oscillates and amplifies between the OPO total reflection mirror (4) and the OPO output mirror (7), and is transmitted through the OPO output mirror (7) and the beam splitter (8) in sequence before being output. The remaining horizontally polarized pump light is transmitted through the second parametric crystal (6) and the OPO output mirror (7) in sequence, and then reflected by the beam splitter (8), and then transmitted through the second polarization beam splitter prism (10) for output. The vertically polarized pump light is reflected by the reflecting mirror (9), the second polarization beam splitter prism (10) and the beam splitter (8) in sequence, and then incident on the OPO output mirror (7), pumping the second parameter crystal (6) to generate parameter transformation to generate second signal light. The second signal light is oscillated and amplified between the OPO total reflection mirror (4) and the OPO output mirror (7), and then transmitted and outputted through the OPO output mirror (7) and the beam splitter (8) in sequence. The remaining vertically polarized pump light is transmitted through the first parameter crystal (5) and the OPO total reflection mirror (4), and then incident on the first polarization beam splitter prism (3), and then reflected and outputted by the first polarization beam splitter prism (3).

2. The dual-wavelength tunable laser device according to claim 1, characterized in that The placement angles of the first parametric crystal (5) and the second parametric crystal (6) relative to the optical path are adjustable.

3. The dual-wavelength tunable laser device according to claim 1 or 2, characterized in that The first parameter crystal (5) and the second parameter crystal (6) are placed independently of each other, or are surface-treated to become bonded crystals.

4. The dual-wavelength tunable laser device according to claim 1 or 2, characterized in that The end faces of the first parametric crystal (5) and the second parametric crystal (6) are plated with anti-reflection films for horizontally polarized pump light, vertically polarized pump light, first signal light and second signal light.

5. The dual-wavelength tunable laser device according to claim 1, characterized in that The OPO total reflection mirror (4) is coated with horizontally polarized pump light and vertically polarized pump light anti-reflection films and first signal light and second signal light total reflection films.

6. The dual-wavelength tunable laser device according to claim 1, characterized in that The OPO output mirror (7) is coated with a horizontally polarized pump light and a vertically polarized pump light anti-reflection film and a first signal light and a second signal light partially transparent partial reflection film, and the transmittance of the first signal light and the second signal light is 20% to 50%.

7. The dual-wavelength tunable laser device according to claim 1, characterized in that The beam splitter (8) is coated with a total reflection film for horizontally polarized pump light and vertically polarized pump light and a first signal light and second signal light anti-reflection film.

8. The dual-wavelength tunable laser device according to claim 1, characterized in that The placement angle of the beam splitter (8) relative to the light path is adjustable.

9. The dual-wavelength tunable laser device according to claim 1, characterized in that The laser light emitted by the pump laser (1) is linearly polarized light.

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