Temperature-driven tunable all-solid-state 1.5-micron cross-polarization dual-wavelength laser

Abstract

The invention discloses a temperature-driven tunable all-solid-state 1.5-micron cross-polarization dual-wavelength laser, and belongs to the technical field of solid lasers. The laser comprises a laser pumping source, a light beam shaping device and a laser resonant cavity which are sequentially arranged along a light path, a cooling device is mounted outside the laser resonant cavity; the laser resonant cavity comprises a laser crystal arranged on a light path; laser emitted by the laser pumping source passes through the light beam shaping device and then is focused and incident into the laser crystal, and the laser crystal is selected from one of an a-cut Er < 3 + > / Yb < 3 + > double-doped borate crystal, an Er < 3 + > / Yb < 3 + > double-doped vanadate crystal and an Er < 3 + > / Yb < 3 + > double-doped yttrium aluminum garnet crystal. The all-solid-state 1.5-micron cross-polarization dual-wavelength laser with tunable power is realized by utilizing the photo-thermal anisotropy of the a-cut Er < 3 + > / Yb < 3 + > double-doped 1.5-micron laser crystal and adjusting the crystal temperature through the cooling device.

Description

Technical Field

[0001] This application relates to a temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser, belonging to the field of solid-state laser technology. Background Technology

[0002] The 1.5-micron orthogonally polarized, eye-safe dual-wavelength laser relates to the field of laser device technology, and is particularly suitable for high-precision and safe detection systems such as laser interferometry, precision metrology, coherent terahertz radiation generation, and eye-safe differential absorption lidar (DIAL). Currently, the 1.5-micron band, due to its excellent optical properties and eye safety, has broad application prospects in industrial inspection, environmental monitoring, and national defense security.

[0003] In existing technologies, achieving 1.5-micron dual-wavelength laser output mainly relies on nonlinear optical processes, such as optical parametric oscillation (OPO) and stimulated Raman scattering (SRS). While these methods can obtain the desired wavelengths, they generally suffer from the following shortcomings:

[0004] a) Complex system structure: The interaction between nonlinear crystals and fundamental frequency waves requires precise optical adjustment, temperature control, and large-area nonlinear material support, making the overall device complex and difficult to achieve a compact design.

[0005] b) High cost: High-quality nonlinear crystals and auxiliary control equipment are expensive, and the maintenance and calibration of complex systems are complicated, resulting in high overall R&D and production costs.

[0006] c) Limited stability: It is greatly affected by environmental factors such as changes in external temperature and light intensity, and the equipment fluctuates frequently during operation, making it difficult to meet the requirements for long-term stable output.

[0007] d) Insufficient polarization control: Existing technologies make it difficult to achieve strictly orthogonal polarization outputs simultaneously, which limits the performance of certain high-precision measurement and signal separation applications.

[0008] The 1.5-micron laser technology has great potential for application in many fields. There is an urgent need to develop a compact, low-cost, stable, and precisely orthogonal polarization-controlled all-solid-state dual-wavelength laser to overcome the shortcomings of traditional nonlinear frequency conversion technology and meet the requirements of high-end applications for system stability and safety performance. Summary of the Invention

[0009] To address the issues of complex structure and high cost of existing 1.5-micron orthogonally polarized dual-wavelength lasers, this application proposes a device technology solution for a temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser.

[0010] The technical solution adopted in this application is as follows:

[0011] According to a first aspect of this application, a temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser is provided, characterized in that it includes a laser pump source, a beam shaping device, and a laser resonant cavity arranged sequentially along the optical path;

[0012] A cooling device is installed outside the laser resonant cavity;

[0013] The laser resonant cavity includes a laser crystal disposed in the optical path;

[0014] The laser emitted from the laser pump source is focused and incident on the laser crystal after passing through the beam shaping device;

[0015] The laser emitted from the laser pump source is split into two pump lasers after passing through the beam shaping device. After passing through the beam shaping device, the pump lasers are injected into the laser crystal in the laser resonator from the injection end of the laser resonator.

[0016] The laser crystal is selected from Er-cut α-type laser crystals. 3+ / Yb 3+ Double-doped borate crystals, Er 3+ / Yb 3+ Double-doped vanadate crystals, Er 3+ / Yb 3+ One type of double-doped yttrium aluminum garnet crystal.

[0017] The laser crystal described in this application converts the pump light transmitted through the pump mirror into laser light and enhances the intensity of the laser light incident on the laser crystal.

[0018] The beam shaping device described in this application is used to adjust the radius of the pump light incident on the laser crystal.

[0019] Optionally, the beam shaping device includes a collimating lens and a focusing lens arranged sequentially along the optical path.

[0020] Optionally, in the beam shaping device, both the collimating lens and the focusing lens are convex lenses, and the collimating lens and the focusing lens are coaxial and their convex surfaces are arranged opposite each other.

[0021] Optionally, the laser resonant cavity further includes a laser pump mirror and a laser output mirror arranged sequentially along the optical path;

[0022] The laser crystal is located between the laser pump mirror and the laser output mirror;

[0023] The laser crystal converts the pump laser transmitted through the laser pump mirror into a 1.5-micron output laser, and the laser output mirror converts the output laser into an orthogonally polarized 1.5-micron laser.

[0024] The pump mirror described in this application is used to transmit the pump light and reflect the output laser emitted from the laser crystal.

[0025] Optionally, the laser pump mirror has a transmittance of 85% or more to the pump laser, and the laser pump mirror has high transmittance to the pump laser and transmits it.

[0026] Optionally, the reflectivity of the laser pump mirror to the output laser is greater than or equal to 99.5%.

[0027] The laser pump mirror has a high reflectivity and reflects the output laser emitted from the laser crystal.

[0028] Optionally, the pump mirror uses a sapphire crystal coated with a 1500-1600nm total reflection film and a 900-1000nm anti-reflection film.

[0029] Optionally, the sapphire crystal is tightly fitted to the pump end of the laser crystal.

[0030] In this application, the laser output mirror is used to reflect and partially transmit the laser emitted from the laser crystal, and the transmitted laser is a pulsed laser.

[0031] Optionally, the transmittance of the laser output mirror to the output laser is 1 to 8%.

[0032] Optionally, the laser output mirror uses a sapphire crystal coated with a 1500-1600nm partial reflective film.

[0033] Optionally, the sapphire crystal is tightly fitted to the output end of the laser crystal.

[0034] Optionally, the laser pump mirror, laser crystal, and laser output mirror are integrated and connected.

[0035] Optionally, the cooling device controls the temperature of the laser crystal, with a control accuracy error of ≤0.1℃.

[0036] Optionally, the cooling device is a water-cooled copper block or a thermoelectric cooler (TEC).

[0037] The beneficial effects of this application include:

[0038] This application provides a temperature-driven, tunable, all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser, using an a-cut Er 3+ / Yb3+ A double-doped 1.5-micron laser crystal can achieve orthogonally polarized 1.5-micron laser output by controlling the crystal temperature and the power intensity of the pump laser. The all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser claimed in this invention has the advantages of simple structure and small size. Attached Figure Description

[0039] Figure 1 Er cut for a 3+ / Yb 3+ Optical power of a double-doped 1.5-micron laser crystal along the horizontal and vertical directions and the difference between the two;

[0040] Figure 2 A schematic diagram of the overall structure of the laser;

[0041] Figure 3 The output power and polarization curve of the laser;

[0042] Figure 4 This refers to the wavelength and polarization direction of the orthogonally polarized laser output from the laser.

[0043] Figure 5 The curves show the variation of orthogonally polarized laser output from the laser with different crystal cooling temperatures.

[0044] List of components and reference numerals:

[0045] 1. Laser pump source; 2. Collimating lens; 3. Focusing lens; 4. Laser pump mirror; 5. Laser crystal; 6. Laser output mirror; 7. Cooling device. Detailed Implementation

[0046] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0047] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0048] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0049] According to one embodiment of this application, the temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser of this application utilizes... a Cut Er 3+ / Yb 3+ The photothermal anisotropy of the double-doped 1.5-micron laser crystal allows for the realization of orthogonally polarized 1.5-micron laser output by controlling the crystal temperature and the power intensity of the pump laser. a Cut Er 3+ / Yb 3+Double-doped 1.5-micron laser crystals generally exhibit photothermal anisotropy, with the crystal along... a shaft and c The photothermal coefficients along the axial direction differ significantly (4.4 × 10⁻⁶). -6 K -1 along a Shaft; 6.7 × 10 -6 K -1 along c (axis), causing the crystal's optical power to be along a shaft and c The axes differ significantly, and the difference gradually increases with increasing pump power, as shown in the crystal optical power variation curve. Figure 1 As shown, as the pump power increases, the crystal moves along... a shaft and c The axial focal length difference will continue to increase, and the crystal along... a shaft and c The gain of the axis also changes continuously. When the pump power reaches the switching threshold, within a certain pump power range, the laser will simultaneously output two linearly polarized lasers with different wavelengths and perpendicular polarization directions.

[0050] In one implementation, such as Figure 2 As shown, a temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser includes a laser pump source 1, a beam shaping device, a laser resonator, and a cooling device 7.

[0051] The beam shaping device includes a collimating lens 2 and a focusing lens 3 spaced apart. The laser resonant cavity includes a laser pump mirror 4 and a laser output mirror 6 spaced horizontally apart. A laser crystal 5 is installed between the laser pump mirror 4 and the laser output mirror 6. The cooling device 7 surrounds the laser pump mirror 4, the laser output mirror 6 and the laser crystal 5 around its periphery.

[0052] The pump laser is incident on the laser crystal 5 from the left after passing through the beam shaping device composed of collimating lens 2 and focusing lens 3. After being stimulated and pumped, the laser crystal 5 achieves laser resonance in the resonant cavity composed of laser pump mirror 4 and laser output mirror 6, and outputs orthogonally polarized 1.5-micron laser through laser output mirror 6.

[0053] In one embodiment, a 976nm semiconductor laser is used as the laser pump source 1 (core diameter of 105um), and both the collimating lens 2 and the focusing lens 3 are plano-convex lenses (focal length of 50mm).

[0054] In one embodiment, the laser resonant cavity comprises a laser pump mirror 4, a laser crystal 5, and a laser output mirror 6. Sapphire, with high thermal conductivity, is used for both the laser pump mirror 4 and the laser output mirror 6. These components are integrated into a single unit. The high thermal conductivity of the laser pump mirror 4 and laser output mirror 6 allows for rapid heat transfer from the laser crystal 5 to the heat sink, thus reducing the crystal temperature. The laser pump mirror 4 is coated with an optical film that provides 92% transmittance for the pump laser at 976 nm and high reflectivity for 1.5 μm lasers, with a reflectivity of 99.95%. The laser output mirror 6 provides 2.5% transmittance for 1.5 μm lasers. The laser crystal 5 is selected from α-cut 1.5 μm laser crystals of Er,Yb:YAB.

[0055] In one embodiment, the cooling device 7 is a water-cooled copper block used to control the crystal temperature.

[0056] In one embodiment, when the temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser of this application operates:

[0057] A pump laser beam emitted by the laser pump source 1 is collimated into a parallel beam by the collimating lens 2, and then focused by the focusing lens 3. It is then injected from the left side into the laser crystal 5 in the laser resonant cavity, thus pumping the laser crystal 5. By adjusting the temperature of the cooling device, the laser can output orthogonally polarized 1.5-micron laser at the output end.

[0058] At a crystal cooling temperature of 15℃ and a pump power of 9.4W, the laser output power and polarization curve are as follows: Figure 3 As shown, the laser output simultaneously exhibits two mutually perpendicular 1.5-micron laser beams in the horizontal and vertical directions within a specific pump power range, with corresponding wavelengths as follows: Figure 4 As shown, the wavelengths are 1551.9nm and 1556.5nm, respectively.

[0059] The laser output power and polarization curves are as follows when the crystal cooling temperatures are 10℃, 15℃, 20℃, and 25℃: Figure 5 As shown, the all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser of this application can achieve different power outputs of orthogonally polarized laser light as the crystal cooling temperature changes. When the crystal cooling temperature is 10℃, 15℃, 20℃, and 25℃, the pump power range of the laser output orthogonally polarized dual wavelengths is 11W, 9.6W, 8.4W, and 6.6W, respectively, and the maximum values ​​for equal dual-wavelength power are 0.52W, 0.44W, 0.38W, and 0.3W, respectively. It is evident that the temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser of this application allows for control of the pump power range of the orthogonally polarized dual wavelengths by adjusting the temperature of the cooling device.

[0060] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A temperature-driven, tunable, all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser, characterized in that, It includes a laser pump source, a beam shaping device, and a laser resonant cavity arranged sequentially along the optical path; A cooling device is installed outside the laser resonant cavity; The laser resonant cavity includes a laser crystal disposed in the optical path; The laser emitted from the laser pump source is focused and incident on the laser crystal after passing through the beam shaping device; The laser crystal is selected from Er-cut α-type laser crystals. 3+ / Yb 3+ Double-doped borate crystals, Er 3+ / Yb 3+ Double-doped vanadate crystals, Er 3 + / Yb 3+ One type of double-doped yttrium aluminum garnet crystal.

2. The temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser according to claim 1, characterized in that, The beam shaping device includes a collimating lens and a focusing lens arranged sequentially along the optical path.

3. The temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser according to claim 1, characterized in that, The laser resonant cavity also includes a laser pump mirror and a laser output mirror arranged sequentially along the optical path; The laser crystal is located between the laser pump mirror and the laser output mirror; The laser crystal converts the pump laser transmitted through the laser pump mirror into a 1.5-micron output laser, and the laser output mirror converts the output laser into an orthogonally polarized 1.5-micron laser.

4. The temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser according to claim 3, characterized in that, The transmittance of the laser pump mirror to the pump laser is greater than or equal to 85%.

5. The temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser according to claim 3, characterized in that, The laser pump mirror has a reflectivity of 99.5% or greater for the output laser.

6. The temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser according to claim 3, characterized in that, The transmittance of the laser output mirror to the output laser is 1-8%.

7. The temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser according to claim 3, characterized in that, The laser pump mirror, laser crystal, and laser output mirror are integrated and connected.

8. The temperature-driven tunable all-solid-state 1.5-micron orthogonally polarized dual-wavelength laser according to claim 1, characterized in that, The cooling device controls the temperature of the laser crystal within a range of 5–30°C, with a control accuracy error of ≤0.1°C.

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