LD end pump pulse solid laser outputting from side edge

Abstract

The utility model discloses an LD end-pumped pulse solid laser outputting from a side edge, which comprises an LD pumping module, a coupling mirror group, a first total reflective mirror, an Nd: YAG crystal rod, a cube-corner prism, a polarization splitting prism, a Q-switch, a wedge mirror group, a second wave plate and a second total reflective mirror which are sequentially arranged, the coupling mirror group is used for focusing fast-axis light spots and slow-axis light spots of the LD pumping module to the Nd: YAG crystal rod, the cube-corner prism is used for folding a laser light path to form a U-shaped structure resonant cavity, the polarization splitting prism is used for dividing laser into p-component polarized light and s-component polarized light, the second wave plate is used for changing the proportion of the p-component polarized light and the s-component polarized light in the resonant cavity, and the second wave plate is used for changing the proportion of the p-component polarized light and the s-component polarized light in the resonant cavity. The second total reflective mirror is used for reflecting the laser to maintain laser oscillation in the resonant cavity. By introducing the polarization splitting prism and rotating the second wave plate, the design flexibility of the laser in a compact space is improved, the length of the whole machine is shortened, the physical cavity length is ensured, and the light beam quality and the laser energy output are optimized.

Description

TECHNICAL FIELD

[0001] The utility model relates to laser diode pumped all solid state laser technical field, especially point to a from side output's LD end pump pulse solid laser. BACKGROUND

[0002] With the continuous development of laser guidance technology, the volume and weight requirements of laser illuminator products are increasingly stringent. This trend poses a major challenge to the design of LD pumped pulse solid state lasers, especially in the context of limited envelope, spatial irregular shape and increasing output parameter requirements. Taking a typical 80mJ laser illuminator as an example, its weight needs to be strictly controlled within 1.5kg, and the overall length should not exceed 200mm, which undoubtedly puts forward very high requirements for the design of the laser.

[0003] In the design of traditional LD end pump solid state laser, the laser oscillates between the full reflection mirror and the output mirror to accumulate energy, and the output mirror is coated with a beam splitting film layer, so that part of the laser can be reflected back into the cavity to continue oscillation and superposition, and another part of the laser is transmitted through the output mirror. However, in the envelope space with strict size and volume limitation, especially when the length is significantly restricted, the traditional design scheme of outputting from the front of the output mirror often cannot meet the needs of the overall structure layout.

[0004] In order to cope with this challenge, designers usually need to adopt the strategy of multiple folding light path to maintain the sufficient physical cavity length of the laser in the limited length, so as to ensure that the laser pulse width meets the requirements. However, this method not only significantly increases the complexity of the laser and the overall structure, improves the manufacturing cost, but also greatly improves the difficulty of debugging and maintenance of the laser. More importantly, multiple folding light path may cause loss of laser energy and degradation of beam quality, which has adverse effects on the performance of the laser. UTILITY MODEL CONTENTS

[0005] Therefore, the utility model provides a kind of LD end pump pulse solid laser from side output, which solves the technical problem of how to maintain the sufficient physical cavity length of the laser and realize the effective output of laser in the envelope space with strict size and volume limitation, especially when the length is limited.

[0006] To achieve the above purpose, the utility model adopts the following technical scheme:

[0007] The utility model discloses a kind of LD end pump pulse solid-state laser output from side, including LD pumping module, coupling mirror group, first full mirror, Nd:YAG crystal rod, pyramidal prism, polarizing beam splitter, Q-switch, wedge mirror group, second wave plate and second full mirror, the LD pumping module is used to provide pump light, the coupling mirror group is arranged in the emission end of the LD pumping module, for the LD pumping module fast axis spot and slow axis spot are focused to the Nd:YAG crystal rod, the first full mirror is arranged on the output light path of the coupling mirror group, the Nd:YAG crystal rod is arranged on the output light path of the first full mirror, for absorbing pump light and emitting laser, the pyramidal prism is arranged on the output light path of the Nd:YAG crystal rod, for folding laser light path, form U-shaped structure resonator, the polarizing beam splitter is arranged on the output light path of the pyramidal prism, for laser is divided into p component polarized light and s component polarized light, and the p component polarized light is allowed to pass through, the s component polarized light is reflected, the Q-switch is arranged on the output light path of the polarizing beam splitter, for controlling laser pulse generation opportunity and characteristic, the wedge mirror group is arranged on the output light path of the Q-switch, for fine tuning the oscillation direction of the light path in the resonator, the second wave plate is arranged on the output light path of the wedge mirror group, for changing the proportion of the p component polarized light and s component polarized light in the resonator, the second full mirror is arranged on the output light path of the second wave plate, and with the first full mirror constitutes plano-convex unstable cavity, for reflecting laser to maintain the laser oscillation in the resonator.

[0008] As a preferred scheme, the LD pumping module includes high-temperature 808nm LD array, and a single LD array is arranged along the fast axis direction of the LD pumping module, the fast axis collimation of the LD pumping module is 3°-5°, the slow axis of the LD pumping module is kept at 10°, and the peak power of the LD pumping module is 1200W-4000W.

[0009] As a preferred scheme, the coupling mirror group is a cylindrical lens combination, and the coupling mirror group focuses the fast axis spot and the slow axis spot of the LD pumping module to the spot size of 2.5mm-3.5mm.

[0010] As a preferred scheme, the first full mirror is a plane mirror, a first high-reflection film is coated on the side surface of the first full mirror close to the Nd:YAG crystal rod, and an anti-reflection film is coated on the side surface of the first full mirror close to the coupling mirror group.

[0011] As a preferred scheme, the coating wavelength of the first high-reflection film is 1064nm, and the coating wavelength of the anti-reflection film is 808nm.

[0012] As a preferred solution, the Nd:YAG crystal rod adopts YAG crystal doped with a gradually changing concentration in the range of 0.5% to 1%, the diameter of the Nd:YAG crystal rod is 4mm to 5mm, the length of the Nd:YAG crystal rod is 20mm to 50mm, and the non-doped YAG crystal is bonded to the front end of the Nd:YAG crystal rod at a distance of 3mm.

[0013] As a preferred solution, the Q-switching device comprises a photoelectric Q-switching crystal and a first wave plate arranged in sequence on the output light path of the polarization beam splitter prism, the photoelectric Q-switching crystal is any one of RTP crystal, KTP crystal and lithium niobate crystal, the size of the photoelectric Q-switching crystal is selected to match the λ / 4 voltage, and the first wave plate is a λ / 4 wave plate.

[0014] As a preferred solution, the second wave plate is a λ / 2 wave plate.

[0015] As a preferred solution, the second total reflection mirror is a plano-convex mirror, the convex surface of the second total reflection mirror faces the second wave plate, and the convex surface of the second total reflection mirror is coated with a second high-reflection film.

[0016] As a preferred solution, the coating wavelength of the second high-reflection film is 1064nm.

[0017] Compared with the prior art, the utility model has obvious advantages and beneficial effects, specifically speaking, from the above technical scheme, it mainly introduces the corner cube prism, the polarization beam splitter prism and the second wave plate which can be rotated to adjust the angle, improves the design flexibility of the laser in the compact space, reduces the mechanical length of the whole machine, the polarization beam splitter prism enables the light path to be output from the middle side position of the resonant cavity, and the rotation of the second wave plate can control the transmittance of the polarization beam splitter prism, thereby adjusting the output of the laser energy, and ensuring that the laser maintains a certain physical cavity length, and the best parameter output of the beam quality and the laser energy is considered.

[0018] To make the structure characteristics and functions of the utility model clearer, the utility model will be described in detail in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 It is the principle diagram of the LD end-pumped pulse solid-state laser resonant cavity of the embodiment of the application and is output from the side;

[0020] Fig. 2 It is the structural schematic diagram of the LD end-pumped pulse solid-state laser of the embodiment of the application and is output from the side.

[0021] EXPLANATION OF REFERENCE NUMERALS:

[0022] 1, LD pump module; 2, coupling mirror group; 3, first full mirror; 4, Nd:YAG crystal rod; 5, corner cube prism; 6, polarization beam splitter prism; 7, Q-switch; 71, photoelectric Q-switching crystal; 72, first wave plate; 8, wedge mirror group; 9, second wave plate; 10, second full mirror. DETAILED DESCRIPTION

[0023] In order to make the purpose of the utility model, technical scheme and advantage more clear and obvious, the utility model is further explained in detail below by combining with the drawings and implementation examples. It should be understood that the specific examples described herein are only used to explain the utility model, and are not used to limit the utility model.

[0024] It should be noted that when an element is referred to as being "fixed" to another element, it can be directly on the other element or there can be intervening elements. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can be present. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0025] Please refer to Figs. 1-2The utility model embodiment provides a kind of LD end pump pulse solid laser from side output, including LD pumping module 1, coupling mirror group 2, first full mirror 3, Nd:YAG crystal rod 4, pyramidal prism 5, polarizing beam splitter 6, Q-switching 7, wedge mirror group 8, second wave plate 9 and second full mirror 10, LD pumping module 1 is used to provide pumping light, provides energy source for the operation of laser.Coupling mirror group 2 is arranged in the emission end of LD pumping module 1, for LD pumping module 1 fast axis spot and slow axis spot is focused to Nd:YAG crystal rod 4, realizes the efficient coupling of pumping light.First full mirror 3 is arranged on the output light path of coupling mirror group 2, reflects pumping light to guide it into resonant cavity, ensure the correct direction of light path.Nd:YAG crystal rod 4 is arranged on the output light path of first full mirror 3, for absorbing pumping light and emitting laser, is the key element of laser generation laser.Pyramidal prism 5 is arranged on the output light path of Nd:YAG crystal rod 4, for folding laser light path, form U type structure resonant cavity, effectively shorten the overall length of laser, and have anti detuning effect, improve laser stability, while maintaining enough physical cavity length.Polarizing beam splitter 6 is arranged on the output light path of pyramidal prism 5, for laser is divided into p component polarized light and s component polarized light, and p component polarized light is allowed to pass through, reflects s component polarized light, realizes the polarization separation and control of laser.Polarizing beam splitter 6 uses quartz material, is the key device for realizing laser from middle side output.Q-switching 7 is arranged on the output light path of polarizing beam splitter 6, for controlling laser pulse generation opportunity and characteristic, ensure the stability and reliability of laser output.Wedge mirror group 8 is arranged on the output light path of Q-switching 7, for fine tuning the oscillation direction of light path in resonant cavity, optimizes the beam quality and directivity of laser.Second wave plate 9 is arranged on the output light path of wedge mirror group 8, for changing the proportion of p component polarized light and s component polarized light in resonant cavity, further regulates and controls the output characteristic of laser.Second full mirror 10 is arranged on the output light path of second wave plate 9, with first full mirror 3 constitutes flat convex unstable cavity, for reflecting laser to maintain laser oscillation in resonant cavity, realizes the effective accumulation and amplification of laser, and effectively outputs laser from side, meet the strict size and volume limit requirement.

[0026] In the embodiment, LD pumping module 1 includes high temperature 808nm LD array, single LD array is arranged along the fast axis direction of LD pumping module 1, ensure the efficient emission and utilization of pumping light.The fast axis collimation of LD pumping module 1 is 3°~5°, to improve the directionality and focusing effect of pumping light.The slow axis of LD pumping module 1 maintains 10° unchanged, to maintain the stability and consistency of pumping light in slow axis direction.The peak power of LD pumping module 1 is 1200W~4000W, provides enough pumping energy to meet the high power output demand of laser.

[0027] The coupling lens group 2 is a cylindrical lens combination, and the coupling lens group 2 focuses the fast-axis spot and the slow-axis spot of the LD pump module 1 to a spot size of 2.5mm-3.5mm of the Nd:YAG crystal rod 4, so as to realize high-efficiency absorption and conversion of the pump light on the crystal rod and improve the energy conversion efficiency of the laser.

[0028] The first full reflection mirror 3 is a plane mirror, and a first high-reflection film is coated on a side of the first full reflection mirror 3 close to the Nd:YAG crystal rod 4, so as to effectively reflect the pump light and reduce energy loss. A low-reflection film is coated on a side of the first full reflection mirror 3 close to the coupling lens group 2, so as to reduce the reflectivity of the pump light reflected from the coupling lens group 2 to the first full reflection mirror 3, further reduce energy loss, and improve the utilization rate of the pump light.

[0029] Further, the coating wavelength of the first high-reflection film is 1064nm, which is accurately matched with the laser wavelength of the Nd:YAG crystal rod 4, so as to realize high-efficiency reflection and reduce energy loss of the laser in the resonant cavity. The coating wavelength of the low-reflection film is 808nm, which is matched with the pump light wavelength of the LD pump module 1, so as to effectively reduce the reflection of the pump light on the first full reflection mirror 3 and improve the transmission rate of the pump light.

[0030] The Nd:YAG crystal rod 4 adopts a YAG crystal doped with a gradually changing concentration in the range of 0.5%-1%, and the laser gain distribution in the Nd:YAG crystal rod 4 is optimized through the gradually changing concentration design, so as to improve the efficiency and stability of the laser. The diameter of the Nd:YAG crystal rod 4 is 4mm-5mm, and the length of the Nd:YAG crystal rod 4 is 20mm-50mm, so as to ensure sufficient gain and make the structure of the laser compact. It should be noted that the length of the Nd:YAG crystal rod 4 is selected according to the design of laser energy. A non-doped YAG crystal is bonded at the front end of the Nd:YAG crystal rod 4, which is used as a heat sink to effectively disperse the heat generated by the Nd:YAG crystal rod 4 during operation, reduce the influence of amplified spontaneous emission, and improve the thermal stability and service life of the laser.

[0031] The Q-switch 7 includes a photoelectric Q-switching crystal 71 and a first wave plate 72 arranged in sequence on the output light path of the polarization beam splitter prism 6, and the voltage of the photoelectric Q-switching crystal 71 is accurately controlled to realize fast switching and modulation of the laser pulse. The photoelectric Q-switching crystal 71 is any one of an RTP crystal, a KTP crystal and a lithium niobate crystal, which have excellent electro-optic effect and stability and are suitable for high-speed Q-switching operation. In particular, the lithium niobate crystal can be used in a low-energy laser. The size of the photoelectric Q-switching crystal 71 is selected to match the λ / 4 voltage, so as to ensure the optimization of the Q-switching effect. The first wave plate 72 is a λ / 4 wave plate, which is used to adjust the polarization state of the laser and cooperates with the photoelectric Q-switching crystal 71 to realize high-efficiency Q-switching function.

[0032] Further, the second wave plate 9 is a λ / 2 wave plate, which is used to further adjust the polarization state of the laser and optimize the output characteristics of the laser. By rotating the angle of the second wave plate 9, the transmittance of the s-component polarized light passing through the polarization beam splitter prism 6 can be changed, so that the laser energy output can be controlled, and the optimal laser parameter output which takes into account the beam quality and the laser energy can be obtained.

[0033] Specifically, in the resonant cavity, the fluorescence generated by the Nd:YAG crystal rod 4 first passes through the polarization beam splitter prism 6 and is converted into p-component polarized light. Subsequently, the p-component polarized light passes through the electro-optic Q-switching crystal loaded with a λ / 4 voltage and a λ / 4 wave plate, and the polarization state thereof is converted into s-component polarized light. When the s-component polarized light passes through the λ / 2 wave plate and the optical axis of the λ / 2 wave plate is rotated to be parallel to the vibration direction of the p-component polarized light, the s-component polarized light is again converted into p-component polarized light. This p-component polarized light is reflected back into the cavity by the second total reflection mirror 10 and still maintains the p-direction polarization state. After passing through the λ / 2 wave plate again, the p-component polarized light is converted into s-component polarized light. Subsequently, the s-component polarized light sequentially passes through the λ / 4 wave plate and the electro-optic Q-switching crystal, and is finally converted into p-component polarized light and transmitted out of the polarization beam splitter prism 6, so that an oscillation loop is formed in the resonant cavity, but no laser is output at this time.

[0034] Therefore, by adjusting the angle between the optical axis of the λ / 2 wave plate and the vibration direction of the polarized light in the resonant cavity, the proportion of the p-component polarized light and the s-component polarized light in the cavity can be changed. In this way, part of the laser continues to oscillate and superimpose in the resonant cavity as p-component polarized light, and another part is output as s-component polarized light from the polarization beam splitter prism 6. When the angle is adjusted to a certain specific value, an effect similar to the optimal transmittance of the conventional output mirror can be achieved, so that the laser energy output with the optimal parameters can be obtained.

[0035] Here, the second total reflection mirror 10 is a plano-convex mirror, and the convex surface of the second total reflection mirror 10 faces the second wave plate 9, which is conducive to the focusing and reflection of the laser. The convex surface of the second total reflection mirror 10 is coated with a second high-reflection film.

[0036] The coating wavelength of the second high-reflection film is 1064 nm, which accurately matches the wavelength of the laser, realizes high-efficiency reflection, and ensures the stable oscillation and amplification of the laser in the resonant cavity.

[0037] In order to make the resonant cavity meet the oscillation condition of the unstable cavity in the full pump power range, the curvature radius of the convex surface of the second total reflection mirror 10 is designed according to the thermal lens focal length of the Nd:YAG crystal rod 4, so as to ensure that g1g2>1.

[0038] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the principles of the present application shall be included in the protection scope of the present application.

Claims

1. A side-pumped LD end-pumped pulsed solid state laser, characterized by: The application relates to a laser device, which comprises an LD pumping module (1), a coupling mirror group (2), a first full reflection mirror (3), a Nd:YAG crystal rod (4), a corner cube prism (5), a polarization beam splitting prism (6), a Q-switch (7), a wedge mirror group (8), a second wave plate (9) and a second full reflection mirror (10), the LD pumping module (1) is used for providing pumping light, the coupling mirror group (2) is arranged at the emitting end of the LD pumping module (1) and is used for focusing fast axis light spots and slow axis light spots of the LD pumping module (1) to the Nd:YAG crystal rod (4), the first full reflection mirror (3) is arranged on the output light path of the coupling mirror group (2), the Nd:YAG crystal rod (4) is arranged on the output light path of the first full reflection mirror (3) and is used for absorbing pumping light and emitting laser, the corner cube prism (5) is arranged on the output light path of the Nd:YAG crystal rod (4) and is used for folding the laser light path to form a U-shaped structure resonant cavity, the polarization beam splitting prism (6) is arranged on the output light path of the corner cube prism (5) and is used for splitting laser into p-component polarized light and s-component polarized light, allowing the p-component polarized light to pass through and reflecting the s-component polarized light, the Q-switch (7) is arranged on the output light path of the polarization beam splitting prism (6) and is used for controlling laser pulse generation time and characteristics, the wedge mirror group (8) is arranged on the output light path of the Q-switch (7) and is used for fine-tuning the oscillation direction of the light path in the resonant cavity, the second wave plate (9) is arranged on the output light path of the wedge mirror group (8) and is used for changing the proportion of the p-component polarized light and the s-component polarized light in the resonant cavity, and the second full reflection mirror (10) is arranged on the output light path of the second wave plate (9) and forms a plano-convex unstable cavity with the first full reflection mirror (3) and is used for reflecting laser to maintain laser oscillation in the resonant cavity.

2. The LD end-pumped pulsed solid-state laser outputting from the side as claimed in claim 1, characterized in that: The LD pumping module (1) comprises high-temperature 808nm LD arrays, and the single LD array is arranged along the fast axis direction of the LD pumping module (1), the fast axis collimation of the LD pumping module (1) is 3-5 degrees, the slow axis of the LD pumping module (1) is kept unchanged at 10 degrees, and the peak power of the LD pumping module (1) is 1200-4000W.

3. The LD end-pumped pulsed solid-state laser outputting from the side as claimed in claim 1, characterized in that: The coupling mirror group (2) is a cylindrical lens group, and the coupling mirror group (2) focuses the fast axis light spots and the slow axis light spots of the LD pumping module (1) to the light spot size of 2.5-3.5mm of the Nd:YAG crystal rod (4).

4. The side-pumped LD end-pumped pulsed solid state laser of claim 1, wherein: The first full reflection mirror (3) is a plane mirror, a first high reflection film is coated on the side of the first full reflection mirror (3) close to the Nd:YAG crystal rod (4), and an anti-reflection film is coated on the side of the first full reflection mirror (3) close to the coupling mirror group (2).

5. The side-pumped solid state laser of claim 4, wherein: The coating wavelength of the first high reflection film is 1064nm, and the coating wavelength of the anti-reflection film is 808nm.

6. The side-pumped LD end-pumped pulsed solid state laser of claim 1, wherein: The Nd:YAG crystal rod (4) adopts YAG crystal doped with a gradually changing concentration in the range of 0.5% to 1%, the diameter of the Nd:YAG crystal rod (4) is 4mm to 5mm, the length of the Nd:YAG crystal rod (4) is 20mm to 50mm, and the front end of the Nd:YAG crystal rod (4) is bonded with a non-doped YAG crystal.

7. The side-pumped solid state laser of claim 1, wherein: The Q-switch (7) comprises a photoelectric Q-switch crystal (71) and a first wave plate (72) arranged on the output light path of the polarization beam splitter prism (6) in sequence, the photoelectric Q-switch crystal (71) is any one of an RTP crystal, a KTP crystal and a lithium niobate crystal, the size of the photoelectric Q-switch crystal (71) is selected to match the λ / 4 voltage, and the first wave plate (72) is a λ / 4 wave plate.

8. The side-pumped solid state laser of claim 1, wherein: The second wave plate (9) is a λ / 2 wave plate.

9. The side-pumped solid state laser of claim 1, wherein: The second total reflection mirror (10) is a plano-convex mirror, the convex surface of the second total reflection mirror (10) faces the second wave plate (9), and the convex surface of the second total reflection mirror (10) is coated with a second high-reflection film.

10. The side-pumped solid state laser of claim 9, wherein: The coating wavelength of the second high-reflection film is 1064nm.

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