All-solid-state 359.5 nm ultraviolet laser

Abstract

The utility model relates to a kind of lasers, especially a kind of full solid 359.5nm ultraviolet laser, including the pump source, collimation focusing system, first crystal and output mirror arranged in sequence, also including back mirror and second crystal, second crystal is located between back mirror and output mirror, output mirror is flat concave lens, and concave surface is towards first crystal and second crystal;Wherein, first crystal is c-cut Pr 3+ :YLF, second crystal is LBO crystal, the front end surface and rear end surface of first crystal are equipped with first film layer and second film layer respectively, the both ends of output mirror are equipped with third film layer and fourth film layer respectively, the mirror surface of back mirror is equipped with fifth film layer.The utility model provides a kind of full solid 359.5nm ultraviolet laser, and 719nm laser is directly generated by Pr:YLF crystal, and 359.5nm laser is directly frequency-doubled by using LBO crystal in cavity, realizes the high integration and solidification from pumping to output, realizes efficient, compact and stable laser output.

Description

Technical Field

[0001] This utility model relates to a laser, and more particularly to an all-solid-state 359.5nm ultraviolet laser. Background Technology

[0002] A 359.5 nm laser is a laser in the ultraviolet band, and this specific wavelength is typically closely related to the transition energy levels of iodine atoms. 359.5 nm lasers are usually generated by pulsed dye lasers or optical parametric oscillators. Therefore, lasers of this wavelength are usually generated from a more common fundamental laser using nonlinear frequency conversion techniques. There are two main approaches: Pulsed dye lasers: This is the most classic generation method. Process: A high-energy pulsed laser (e.g., frequency-doubled light of an Nd:YAG laser at 532 nm) pumps a dye laser. The dye laser uses a specific organic dye solution (e.g., LDS698 dye), whose output wavelength is tunable in the visible or near-infrared band. Then, through frequency doubling, the output frequency of the dye laser is doubled, resulting in ultraviolet light with half the wavelength. 719 nm (dye laser) → frequency doubling → 359.5 nm (ultraviolet laser). Optical parametric oscillator / amplifier + frequency doubling; the OPO can be pumped by a solid-state laser such as Nd:YAG to generate tunable infrared light in a nonlinear crystal. Then, the OPO output is frequency-doubled to the ultraviolet band using the same frequency doubling crystal.

[0003] This method, which uses birefringence, FP etalons, and other techniques to obtain 719nm laser light and then frequency-doubles it to obtain 359.5nm laser light, is complex, often requiring multi-stage laser systems and nonlinear frequency conversion. The equipment is large, expensive, and difficult to maintain; its reliability is poor: the FP etalon and the entire optical cavity are extremely sensitive to temperature fluctuations, vibrations, and airflow. Even slight vibrations in the laboratory or the switching on and off of the air conditioner can cause laser mode "mode skipping" or fluctuations in output power. Utility Model Content

[0004] To address the aforementioned problems, this utility model provides an all-solid-state 359.5nm ultraviolet laser, the specific technical solution of which is as follows: An all-solid-state 359.5nm ultraviolet laser includes a pump source, a collimation and focusing system, a first crystal, and an output mirror arranged sequentially. It also includes a rear reflector and a second crystal, the second crystal being located between the rear reflector and the output mirror. The output mirror is a plano-concave lens, with its concave surface facing the first and second crystals. The first crystal is a c-cut Pr... 3+ YLF, the second crystal is an LBO crystal, the front end face and the rear end face of the first crystal are respectively provided with a first film layer and a second film layer, the two ends of the output mirror are respectively provided with a third film layer and a fourth film layer, and the reflective surface of the rear reflector is provided with a fifth film layer.

[0005] Preferably, the pump source is a 441nm laser diode.

[0006] Preferably, the LBO crystal uses type I phase matching, with a cutting angle of θ=90° and Ф=40.8°. The crystal end faces are coated with AR@719nm & 359.5nm.

[0007] Preferably, the first film layer comprises HT@441nm and HR@719nm.

[0008] Preferably, the second film layer comprises AR@719nm, HT@607nm, 640nm, and 719nm.

[0009] Preferably, the third film layer comprises HR%@719nm, HT@607nm & 640nm, and HT@359.5nm.

[0010] Preferably, the fourth film layer comprises AR@359.5nm.

[0011] Preferably, the fifth film layer comprises HR@719nm & 359.5nm.

[0012] Preferably, a sixth film layer is provided at both ends of the second crystal.

[0013] Furthermore, the sixth film layer comprises AR@719nm & 359.5nm.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an all-solid-state 359.5nm ultraviolet laser that directly generates 719nm laser light using a Pr:YLF crystal and directly generates 359.5nm laser light using an LBO crystal within the cavity. This achieves high integration and solid-state design from pump to output, resulting in efficient, compact, and stable laser output. Attached Figure Description

[0015] Figure 1 This is a structural diagram of this application. Detailed Implementation

[0016] The present invention will now be further described with reference to the accompanying drawings.

[0017] like Figure 1As shown, an all-solid-state 359.5nm ultraviolet laser includes a pump source 1, a collimation and focusing system 2, a first crystal 3, and an output mirror 4 arranged sequentially. It also includes a rear reflector 5 and a second crystal 6, with the second crystal 6 located between the rear reflector 5 and the output mirror 4. The output mirror 4 is a plano-concave lens, with its concave surface facing the first crystal 3 and the second crystal 6. The first crystal 3 is a c-cut Pr... 3+ YLF, the second crystal 6 is an LBO crystal, the front end and rear end of the first crystal 3 are respectively provided with a first film layer 71 and a second film layer 72, the two ends of the output mirror 4 are respectively provided with a third film layer 73 and a fourth film layer 74, and the reflector surface of the rear reflector 5 is provided with a fifth film layer 75.

[0018] Pump source 1 is a 441nm laser diode.

[0019] The LBO crystal uses type I phase matching with a cutting angle of θ=90° and Ф=40.8°. The crystal's two end faces are coated with AR@719nm & 359.5nm.

[0020] The light emitted by the 441nm laser diode is collimated and focused by the optical system onto the c-cut Pr 3+ Within the YLF crystal, the front end of the first crystal 3 is coated with HT@441nm and HR@719nm, and the rear end of the first crystal 3 is coated with AR@719nm, HT@607nm, 640nm, and 719nm.

[0021] Pr:YLF lasers exhibit emission peaks at both ~719 nm and ~721 nm, with a typically stronger gain at 721 nm. If the resonant cavity provides feedback for both wavelengths, the laser will preferentially oscillate at 721 nm.

[0022] The c-cut Pr3+:YLF crystal emits only delta-polarized spectral lines and suppresses π-polarized lines. Therefore, only the delta-polarized 719nm spectral line can form laser light, while the π-polarized 721nm spectral line is suppressed. Then, through the nonlinear effect of the LBO crystal, a 359.5nm laser light is formed.

[0023] Concave coating of output mirror 4: HR%@719nm, HT@607nm & 640nm, HT@359.5nm, and the planar coating AR@359.5nm of output mirror 4.

[0024] The reflective surface coating of rear mirror 5 is HR@719nm & 359.5nm.

[0025] The LBO crystal employs Type I phase matching, with a cut angle of θ=90° and Ф=40.8°. The crystal's end faces are coated with AR at 719nm and 359.5nm. This application employs a simple method to obtain a 359.5nm laser that differs from the 360.5nm laser.

[0026] The second crystal 6 has a sixth film layer 76 at both ends, and the sixth film layer 76 is AR@719nm&359.5nm.

[0027] All-solid-state design: Using a 441nm laser diode as the pump source and a solid crystal as the gain medium, this system completely eliminates the organic dye solution, circulation pump, and complex maintenance required by traditional dye lasers. Compared with traditional dye lasers, this system has overwhelming advantages such as compact structure, long lifespan, high stability, simple maintenance, and fast start-up.

[0028] Highly efficient direct pumping and energy level matching: The absorption peak of the Pr:YLF crystal perfectly matches the output wavelength of the 441nm laser diode, enabling direct excitation of Pr ions to the upper energy level, thereby generating the required 719nm radiation. This direct pumping method boasts high quantum efficiency and low thermal load.

[0029] The film achieves high-efficiency resonance and low loss. The front end of the first crystal (HT@441nm, HR@719nm) allows the pump light to pass through efficiently into the gain crystal, reflecting the generated 719nm laser back to the resonant cavity, which together with the rear mirror forms a stable resonant cavity for 719nm.

[0030] The first crystal rear end face (AR@719nm) is anti-reflective at 719nm, minimizing the reflection loss of 719nm light at the crystal end face, allowing it to pass through without loss and enter the frequency doubling crystal.

[0031] The third film layer of the output mirror (HR@719nm, HT@359.5nm) has high reflectivity at 719nm, allowing it to continue oscillating inside the cavity to accumulate extremely high power density, which greatly improves the frequency doubling efficiency. At the same time, it has high transmittance at 359.5nm, allowing the generated ultraviolet laser to be efficiently output outside the cavity.

[0032] The rear reflector (HR@719nm & 359.5nm) not only reflects 719nm, but also reflects 359.5nm that may have been transmitted, allowing it to pass through the LBO crystal again and participate in the nonlinear process, thus improving the extraction efficiency of ultraviolet light.

[0033] With its high nonlinear conversion efficiency, LBO features a high damage threshold, moderate nonlinear coefficient, wide receiver bandwidth, and small walk-off angle, making it ideal for frequency doubling in high power density cavities. Its Class I phase-matching design and precise cut angle ensure efficient conversion from 719nm to 359.5nm.

[0034] The LBO's two ends are coated with AR@719nm & 359.5nm, which simultaneously eliminates the reflection loss of the fundamental frequency light (719nm) and the frequency-doubled light (359.5nm) at the crystal end face, further reducing the operating threshold of the entire system and improving the conversion efficiency.

[0035] Effective thermal management and suppression of parasitic oscillations: The first crystal back facet (HT@607nm & 640nm & 719nm): While the Pr:YLF crystal generates 719nm, it may also generate radiation of other wavelengths (such as 607nm and 640nm). This film layer allows these parasitic wavelengths to transmit out instead of oscillating within the cavity. This effectively suppresses parasitic oscillations, ensuring the dominance and purity of the 719nm laser, thereby stabilizing the final 359.5nm output.

[0036] Compact and stable resonant cavity: The output mirror adopts a plano-concave lens with the concave surface facing the gain medium, which is easy to adjust and has a high tolerance for processing and assembly errors, ensuring mode stability and power stability of the laser during long-term operation.

[0037] The technical principles of this utility model have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this utility model and should not be construed as limiting the scope of protection of this utility model in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this utility model without inventive effort, and these embodiments will all fall within the protection scope of the claims of this utility model.

Claims

1. An all-solid-state 359.5nm ultraviolet laser, characterized in that, It includes a pump source (1), a collimation and focusing system (2), a first crystal (3) and an output mirror (4) arranged in sequence, and also includes a rear reflector (5) and a second crystal (6). The second crystal (6) is located between the rear reflector (5) and the output mirror (4). The output mirror (4) is a plano-concave lens, and its concave surface faces the first crystal (3) and the second crystal (6). Among them, the first crystal (3) is c-cut Pr 3+ YLF, the second crystal (6) is an LBO crystal, the front end face and the rear end face of the first crystal (3) are respectively provided with a first film layer (71) and a second film layer (72), the two ends of the output mirror (4) are respectively provided with a third film layer (73) and a fourth film layer (74), and the reflector (5) surface of the rear reflector (5) is provided with a fifth film layer (75).

2. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The pump source (1) is a 441nm laser diode.

3. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The LBO crystal uses type I phase matching, with a cutting angle of θ=90° and Ф=40.8°. The crystal's two end faces are coated with AR@719nm & 359.5nm.

4. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The first film layer (71) includes HT@441nm and HR@719nm.

5. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The second film layer (72) includes AR@719nm, HT@607nm&640nm&719nm.

6. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The third film layer (73) includes HR%@719nm, HT@607nm & 640nm, and HT@359.5nm.

7. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The fourth film layer (74) includes AR@359.5nm.

8. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The fifth film layer (75) includes HR@719nm & 359.5nm.

9. The all-solid-state 359.5nm ultraviolet laser according to claim 1, characterized in that, The second crystal (6) has a sixth film layer (76) at both ends.

10. A 359.5nm all-solid-state ultraviolet laser according to claim 9, characterized in that, The sixth film layer (76) includes AR@719nm & 359.5nm.

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