Single longitudinal mode laser

Abstract

A single longitudinal mode laser provided by the present invention comprises a pumping system and a resonant cavity structure, the resonant cavity structure is composed of a gain assembly, a polarizer, a plurality of laser cavity mirrors and a reflective volume Bragg grating, and the pumping system pumps from one end or multiple ends of the resonant cavity structure to enter the resonant cavity structure. Laser emitted by the pumping system passes through the resonant cavity structure and then outputs single longitudinal mode laser, the resonant cavity structure is arranged on the resonant cavity platform, and the reflective volume Bragg grating is controlled by external temperature. The single longitudinal mode laser can realize stable, low-noise and high-power single longitudinal mode output; the single longitudinal mode laser only needs to supply power to the pumping system, does not need to control the temperature of the resonant cavity platform, only needs to control the temperature of the reflection type volume Bragg grating and the selected nonlinear crystal, is small in overall heating amount, is lower in power consumption, and can work at a wider environment temperature range.

Description

Technical Field

[0001] The present invention relates to the technical field related to lasers, and more precisely to a single longitudinal mode laser. Background Art

[0002] Compared with multi-mode lasers, single longitudinal mode lasers have the advantages of longer coherence length, narrower spectral line width, and better beam quality. They are widely used in various fields such as atomic and molecular physics, measurement, communication, and biology. The existing methods for obtaining single longitudinal mode in solid-state single longitudinal mode lasers include short cavity method, Fabry-Perot etalon method, seed light injection method, twisted mode cavity method, ring cavity method, and the combination of the above methods. Among them, the method of inserting frequency-selective devices such as etalons and birefringent filters to select the longitudinal mode requires temperature control of the solid-state gain medium to counteract the interference problem of temperature gradient changes. The ring cavity or torsion pendulum cavity has high difficulty in adjusting the resonant cavity, and it is difficult to achieve stable and low-noise single longitudinal mode output. Optically pumped vertical external-cavity surface-emitting semiconductor lasers (VECSELs) include distributed Bragg reflectors (DBRs) and active regions, but the distributed Bragg reflectors have large thermal resistance, resulting in limited overall output power.

[0003] In summary, the art needs to improve the existing single longitudinal mode lasers to achieve stable, low-noise, high-power single longitudinal mode output with lower energy consumption and the ability to operate in a wider range of ambient temperatures. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a single longitudinal mode laser, comprising a pumping system and a resonant cavity structure, wherein the resonant cavity structure is composed of a reflective volume Bragg grating, a gain element, a laser cavity mirror, and a polarizer, wherein only the pumping system needs to be powered, and only the reflective volume Bragg grating needs to be temperature controlled, thereby achieving stable, low-noise, high-power single longitudinal mode output.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a single longitudinal mode laser, including a pump system and a resonant cavity structure, the resonant cavity structure is composed of a gain component, a polarizer, a plurality of laser cavity mirrors, and a reflective volume Bragg grating. The pump system pumps the incident resonant cavity structure from one end or multiple ends of the resonant cavity structure, and the laser emitted by the pump system outputs a single longitudinal mode laser after passing through the resonant cavity structure. The resonant cavity structure is arranged on a resonant cavity platform, and the reflective volume Bragg grating is controlled by external temperature.

[0006] Preferably, the resonant cavity structure comprises a gain component, a polarizer, a laser cavity mirror, and a reflective volume Bragg grating arranged in sequence.

[0007] Preferably, the side of the gain component facing the pump system is coated with a pump light anti-reflection film and a fundamental frequency light high-reflection film to form a light-input end cavity mirror of the resonant cavity structure; the side of the gain component away from the pump system is coated with a fundamental frequency light anti-reflection film, and the two light-passing sides of the reflective volume Bragg grating are coated with fundamental frequency light and frequency-doubled light anti-reflection films to form a light-output end cavity mirror of the resonant cavity structure.

[0008] Preferably, a frequency doubling nonlinear crystal is arranged between the laser cavity mirror and the reflective volume Bragg grating.

[0009] Preferably, the polarizer is a Brewster angle incident element without coating.

[0010] Preferably, the pumping system performs pumping from both sides of the resonant cavity structure, and the output laser is emitted in a direction perpendicular to the pumping light at both ends; the resonant cavity structure comprises a reflective volume Bragg grating, a gain component, a polarizer arranged at 45°, an upper cavity mirror and a lower cavity mirror arranged in sequence, the reflective volume Bragg grating and the gain component share a common optical axis, the upper cavity mirror and the lower cavity mirror share a common optical axis, and the optical axes of the gain component and the upper cavity mirror are perpendicular to each other and intersect at the polarizer.

[0011] Preferably, the side of the reflective volume Bragg grating away from the gain component is coated with a pump light anti-reflection film, and the side facing the gain component is coated with a pump light and fundamental frequency light anti-reflection film, forming a cavity mirror at one end of the resonant cavity structure, and both sides of the gain component are coated with pump light and fundamental frequency light anti-reflection films; the polarizer set at 45° is coated with a fundamental frequency light polarization high-reflection film, a frequency-doubled light and pump light anti-reflection film, the upper cavity mirror is coated with a fundamental frequency light and frequency-doubled light anti-reflection film, and the lower cavity mirror is coated with a fundamental frequency light and frequency-doubled light high-reflection film, forming a cavity mirror at one end of the resonant cavity structure.

[0012] Preferably, a frequency doubling nonlinear crystal is arranged between the upper cavity mirror and the lower cavity mirror.

[0013] Preferably, the gain component comprises a semiconductor thin-slice gain medium located in the middle and an etalon arranged at both the front and rear sides of the semiconductor thin-slice gain medium.

[0014] Preferably, the pumping system uses a conductor laser with a wavelength of 800-815 nm.

[0015] Compared with the prior art, the advantages of a single longitudinal mode laser disclosed in the present invention are: the single longitudinal mode laser can achieve stable, low-noise, high-power single longitudinal mode output; the single longitudinal mode laser only needs to power the pump system, and does not need to perform temperature control on the resonant cavity platform. It only needs to perform temperature control on the reflective volume Bragg grating and the optional nonlinear crystal. The overall heat generation is small, the power consumption is lower, and it can operate in a wider range of ambient temperatures; the resonant cavity structure of the single longitudinal mode laser is more compact, which can meet the needs of small-size packaging products. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] like Figure 1 Shown is a schematic structural diagram of a first preferred embodiment of a single longitudinal mode laser of the present application.

[0018] like Figure 2 Shown is a schematic structural diagram of a second preferred embodiment of a single longitudinal mode laser of the present application. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figure 1The first preferred embodiment of a single longitudinal mode laser of the present application is shown. The single longitudinal mode laser comprises a pump system 1 and a resonant cavity structure. The resonant cavity structure comprises a gain component 2, a polarizer 3, a laser cavity mirror 4, and a reflective volume Bragg grating 5 arranged in sequence. The laser emitted by the pump system 1 outputs a single longitudinal mode laser after passing through the resonant cavity structure. The resonant cavity structure is arranged as a whole on the resonant cavity platform. The resonant cavity platform does not need to be temperature controlled. Only the reflective volume Bragg grating 5 needs to be temperature controlled. The polarizer 3 can select a Brewster angle incident element without coating. By temperature controlling the reflective volume Bragg grating 5, its reflection wavelength shift follows the wavelength shift caused by the temperature change of the resonant cavity platform. The single longitudinal mode laser can achieve stable, low-noise, high-power single longitudinal mode output; the single longitudinal mode laser only needs to power the pump system, does not need to temperature control the resonant cavity platform, and only needs to temperature control the reflective volume Bragg grating and the optional nonlinear crystal. The overall heat generation is small, the power consumption is lower, and it can work at a wider range of ambient temperatures.

[0021] The pump system preferably uses a conductor laser with a wavelength of 800 to 815 nm. The side of the gain component 2 facing the pump system 1 is coated with a pump light anti-reflection film and a fundamental frequency light high-reflection film to form a cavity mirror at the light input end of the resonant cavity structure. The side of the gain component 2 away from the pump system 1 is coated with a fundamental frequency light anti-reflection film, and the two light-passing sides of the reflective volume Bragg grating 5 are coated with fundamental frequency light and frequency-doubled light anti-reflection films to form a cavity mirror at the light output end of the resonant cavity structure. The resonant cavity structure is more compact and can meet the needs of small-size packaging products.

[0022] The gain component 2 includes a semiconductor thin-slice gain medium 21 located in the middle and an etalon 22 arranged on the front and rear sides of the semiconductor thin-slice gain medium 21. The semiconductor thin-slice gain medium 21 is selected according to the type of the laser wavelength used, and the etalon 22 uses an optical-grade heat-conducting medium with a high thermal conductivity. The thickness of the heat-conducting medium is determined according to the thermal conductivity required by the energy of the pump system 1. The transmission peak wavelength shift caused by the temperature change of the material used is close to the wavelength shift caused by the temperature change of the resonant cavity platform material. The etalon 22 on the side of the semiconductor thin-slice gain medium 21 facing the pump system 1 is coated with a pump light anti-reflection film and a fundamental frequency light high-reflection film to form a cavity mirror at the light input end of the resonant cavity structure; the etalon 22 on the side of the semiconductor thin-slice gain medium 21 away from the pump system 1 is coated with a fundamental frequency light anti-reflection film.

[0023] The semiconductor thin-film gain medium 21 provides a wide gain bandwidth and can adapt to a wider range of working environment temperature. When the resonant cavity platform is affected by temperature changes, the etalon 22 and the reflective volume Bragg grating 5 will produce wavelength shifts. The wavelength tracking is performed only by temperature control of the reflective volume Bragg grating 5, thereby obtaining gain compensation. The temperature control of the reflective volume Bragg grating 5 changes with the temperature change of the etalon 22, that is, the reflection wavelength shift of the reflective volume Bragg grating 5 is consistent with the wavelength shift of the etalon 22 through temperature control. It is preferred that the reflection wavelength bandwidth of the reflective volume Bragg grating 5 is smaller than the transmission peak wavelength interval of the etalon 22.

[0024] Furthermore, a frequency doubling nonlinear crystal 6 is arranged between the laser cavity mirror 4 and the reflective volume Bragg grating 5. The nonlinear crystal 6 may be LBO, LiNbO3, CLBO, β-BBO, KTP, BIBO, and periodically polarized crystals PPLN, PPMgLN, PPKTP, PPRTA, etc. When the nonlinear crystal 6 is arranged, it is necessary to perform temperature control on it.

[0025] like Figure 2 The second preferred embodiment of a single longitudinal mode laser of the present application is shown. The single longitudinal mode laser of this embodiment has a higher output power. The single longitudinal mode laser includes a pumping system 1 and a resonant cavity structure. The pumping system 1 is pumped from both sides of the resonant cavity structure, and the output laser is emitted in a direction perpendicular to the pumping light at both ends. The resonant cavity structure includes a reflective volume Bragg grating 5, a gain component 2, a polarizer 3 set at 45°, an upper cavity mirror 41 and a lower cavity mirror 42 arranged in sequence, wherein the reflective volume Bragg grating 5 and the gain component 2 share an optical axis, the upper cavity mirror 41 and the lower cavity mirror 42 share an optical axis, the optical axes of the gain component 2 and the upper cavity mirror 41 are perpendicular to each other and intersect at the polarizer 3, and the pumping system 1 pumps from the reflective volume Bragg grating 5 and the polarizer 3 to the resonant cavity structure respectively. The resonant cavity structure is arranged as a whole on the resonant cavity platform, and the resonant cavity platform does not need to be temperature controlled, and only the reflective volume Bragg grating 5 needs to be temperature controlled. By temperature controlling the reflective volume Bragg grating 5, the reflected wavelength shift follows the wavelength shift caused by the temperature change of the resonant cavity platform. The single longitudinal mode laser can achieve stable, low-noise, high-power single longitudinal mode output; the single longitudinal mode laser only needs to power the pump system, does not need to temperature control the resonant cavity platform, and only needs to temperature control the reflective volume Bragg grating and the optional nonlinear crystal, so the overall heat generation is small, the power consumption is lower, and it can work in a wider range of ambient temperatures.

[0026] The pump system preferably uses a conductor laser with a wavelength of 800 to 815 nm. The side of the reflective volume Bragg grating 5 away from the gain component 2 is coated with a pump light anti-reflection film, and the side facing the gain component is coated with a pump light and fundamental frequency light anti-reflection film, forming a cavity mirror at one end of the resonant cavity, and both sides of the gain component 2 are coated with pump light and fundamental frequency light anti-reflection films. The polarizer 3 set at 45° is coated with a fundamental frequency light polarization high reflection film, a frequency doubling light and pump light anti-reflection film, the upper cavity mirror 41 is coated with a fundamental frequency light and frequency doubling light anti-reflection film, and the lower cavity mirror is coated with a fundamental frequency light and frequency doubling light high reflection film, forming a cavity mirror at one end of the resonant cavity.

[0027] Furthermore, a frequency doubling nonlinear crystal 6 is arranged between the upper cavity mirror 41 and the lower cavity mirror 42. The nonlinear crystal 6 may be LBO, LiNbO3, CLBO, β-BBO, KTP, BIBO, and periodically poled crystals PPLN, PPMgLN, PPKTP, PPRTA, etc. When the nonlinear crystal 6 is arranged, it is necessary to perform temperature control on it.

[0028] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A single longitudinal mode laser, characterized in that: The invention comprises a pump system and a resonant cavity structure, wherein the resonant cavity structure is composed of a gain component, a polarizer, a plurality of laser cavity mirrors, and a reflective volume Bragg grating. The pump system pumps the incident resonant cavity structure from one or more ends of the resonant cavity structure. The laser emitted by the pump system outputs a single longitudinal mode laser after passing through the resonant cavity structure. The resonant cavity structure is arranged on a resonant cavity platform, and the reflective volume Bragg grating is controlled by external temperature.

2. The single longitudinal mode laser according to claim 1, characterized in that: The resonant cavity structure comprises a gain component, a polarizer, a laser cavity mirror and a reflective volume Bragg grating which are arranged in sequence.

3. The single longitudinal mode laser according to claim 2, characterized in that: The side of the gain component facing the pump system is coated with a pump light anti-reflection film and a fundamental frequency light high-reflection film to form a cavity mirror at the light input end of the resonant cavity structure; the side of the gain component away from the pump system is coated with a fundamental frequency light anti-reflection film, and the two light-transmitting sides of the reflective volume Bragg grating are coated with fundamental frequency light and frequency-doubled light anti-reflection films to form a cavity mirror at the light output end of the resonant cavity structure.

4. The single longitudinal mode laser according to claim 2, characterized in that: A frequency doubling nonlinear crystal is arranged between the laser cavity mirror and the reflective volume Bragg grating.

5. The single longitudinal mode laser according to claim 2, characterized in that: The polarizer is a Brewster angle incident element without coating.

6. The single longitudinal mode laser according to claim 1, characterized in that: The pumping system performs pumping from both sides of the resonant cavity structure, and the output laser is emitted in a direction perpendicular to the pumping light at both ends; the resonant cavity structure comprises a reflective volume Bragg grating, a gain component, a polarizer arranged at 45 degrees, an upper cavity mirror and a lower cavity mirror, which are arranged in sequence, the reflective volume Bragg grating and the gain component share a common optical axis, the upper cavity mirror and the lower cavity mirror share a common optical axis, and the optical axes of the gain component and the upper cavity mirror are perpendicular to each other and intersect at the polarizer.

7. The single longitudinal mode laser according to claim 6, characterized in that: The side of the reflective volume Bragg grating away from the gain component is coated with a pump light anti-reflection film, and the side facing the gain component is coated with a pump light and fundamental frequency light anti-reflection film, forming a cavity mirror at one end of the resonant cavity structure, and both sides of the gain component are coated with pump light and fundamental frequency light anti-reflection films; the polarizer set at 45° is coated with a fundamental frequency light polarization high reflection film, a frequency doubled light and pump light anti-reflection film, the upper cavity mirror is coated with a fundamental frequency light and frequency doubled light anti-reflection film, and the lower cavity mirror is coated with a fundamental frequency light and frequency doubled light high reflection film, forming a cavity mirror at one end of the resonant cavity structure.

8. The single longitudinal mode laser according to claim 6, characterized in that: A frequency doubling nonlinear crystal is arranged between the upper cavity mirror and the lower cavity mirror.

9. The single longitudinal mode laser according to claim 1, characterized in that: The gain component comprises a semiconductor thin-slice gain medium located in the middle and an etalon arranged at both the front and rear sides of the semiconductor thin-slice gain medium.

10. The single longitudinal mode laser according to claim 1, characterized in that: The pumping system adopts a conductor laser with a wavelength of 800-815nm.

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