Picosecond laser

Abstract

The utility model discloses a picosecond laser. The picosecond laser comprises a pumping source, a laser shaping assembly, an amplification cavity and a picosecond laser seed source. The pumping source is used for emitting pumping light; the laser shaping assembly is in butt joint with the output end of the pumping source and is used for shaping the pumping light so as to form laser spots with uniform light intensity distribution on a focal plane; the amplification cavity is in butt joint with the output end of the laser shaping assembly and comprises a dichroscope and a first reflecting mirror which are oppositely arranged, and a laser gain crystal between the dichroscope and the first reflecting mirror; the shaped pump light is transmitted and focused on the laser gain crystal by the dichroscope; seed laser emitted by the picosecond laser seed source is reflected for multiple times between the dichroscope and the first reflector, and laser is output after multi-pass amplification is carried out on the seed laser through the laser gain crystal for multiple times. According to the invention, the energy distribution of the laser gain crystal is uniform, the amplification process of the seed laser in the crystal is more uniform, the laser output stability is improved, and the laser efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser, in particular to a picosecond laser. BACKGROUND

[0002] In the field of laser technology, the seed light of picosecond is usually a fiber mode-locked laser, and its output power is in the order of nJ. According to the pulse laser amplification theory, the first stage of solid-state amplification hopes that the seed light can pass through the laser gain crystal as many times as possible to fully extract the energy of the crystal for amplification.

[0003] Among them, the pump light is the energy source of laser generation, and its quality and distribution have a crucial influence on the performance and output characteristics of the laser. In the traditional design of laser, the pump light is often directly irradiated on the laser gain crystal. However, due to the uneven distribution of pump light intensity and poor beam quality, it often leads to uneven energy distribution in the gain medium, thereby affecting the extraction of crystal energy by the seed light, and ultimately resulting in poor quality and stability of the amplified output laser. CONTENT OF THE UTILITY MODEL

[0004] The present application provides a picosecond laser, which aims to solve the problem that the uneven distribution of pump light intensity and poor beam quality ultimately affect the quality and stability of the amplified output laser in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides a picosecond laser. The picosecond laser comprises:

[0006] a pump source for emitting pump light;

[0007] a laser shaping assembly arranged at the output end of the pump source, for shaping the pump light to form a laser spot with uniform light intensity distribution on the focal plane;

[0008] an amplification cavity arranged at the output end of the laser shaping assembly, the amplification cavity comprising a dichroic mirror and a first mirror arranged oppositely, and a laser gain crystal arranged between the two; the shaped pump light is transmitted by the dichroic mirror and focused on the laser gain crystal;

[0009] a picosecond laser seed source for emitting seed light;

[0010] Among them, the seed light is reflected between the dichroic mirror and the first mirror multiple times, and the seed light passes through the laser gain crystal multiple times for multi-pass amplification and then outputs laser.

[0011] In some embodiments, the pump source is a semiconductor bar laser.

[0012] In some embodiments, the laser shaping assembly comprises a collimating mirror and a beam homogenization module arranged in sequence along an optical path, and the pump light emitted by the semiconductor bar laser is shaped by the collimating mirror and the beam homogenization module and then focused on the laser gain crystal.

[0013] In some embodiments, the beam homogenization module comprises a double-row microlens array and an integrating lens arranged in sequence along an optical path.

[0014] In some embodiments, the integrating lens is a plano-convex focusing lens.

[0015] In some embodiments, the amplification cavity further comprises an incidence adjusting mirror and an output adjusting mirror, the incidence adjusting mirror is used to adjust the incidence angle of the seed laser, and the output adjusting mirror is used to adjust the output angle of the amplified laser.

[0016] The incidence adjusting mirror and the output adjusting mirror are matched to jointly adjust the number of times the seed laser passes through the laser gain crystal in the amplification cavity.

[0017] In some embodiments, the laser gain crystal has a shape of a slab.

[0018] In some embodiments, the laser gain crystal comprises neodymium-doped yttrium vanadate, neodymium-doped yttrium aluminum garnet, neodymium-doped lithium yttrium fluoride, and ytterbium-doped yttrium aluminum garnet.

[0019] The technical scheme of the present application provides a picosecond laser. The picosecond laser comprises a pump source, a laser shaping assembly, an amplification cavity, and a picosecond laser seed source. The pump source is used to emit pump light; the laser shaping assembly is arranged at the output end of the pump source and is used to shape the pump light to form a laser spot with uniform light intensity distribution on a focal plane; the amplification cavity is arranged at the output end of the laser shaping assembly and comprises a dichroic mirror and a first mirror arranged oppositely, and a laser gain crystal arranged between the two; the shaped pump light is transmitted by the dichroic mirror and focused on the laser gain crystal; the picosecond laser seed source is used to emit seed laser; and the seed laser is reflected multiple times between the dichroic mirror and the first mirror to pass through the laser gain crystal multiple times for multi-pass amplification and then output laser. According to the technical scheme of the present application, the pump light emitted by the pump source is shaped by the laser shaping assembly to form a laser beam with uniform light intensity, and the energy distribution of the laser gain crystal is uniform when the pump light is incident on the laser gain crystal, so that the amplification process of the seed laser in the crystal is also more uniform, the stability of the laser output is improved, the energy in the crystal is effectively extracted, and the laser efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 Figure 1 is a structural schematic diagram of a picosecond laser according to an embodiment of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of the present application.

[0023] It should be noted that all directional indications, such as upper, lower, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0024] It should also be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or can have a middle element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or can have a middle element.

[0025] In addition, the description involving "first", "second", etc. in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that the technical solutions can be realized by those skilled in the art, and when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0026] Reference Figure 1As shown, the application provides a picosecond laser. The picosecond laser comprises a pump source 10, a laser shaping assembly 20, an amplification cavity 30 and a picosecond laser seed source 40. The pump source 10 is configured to emit pump light; the laser shaping assembly 20 is arranged at the output end of the pump source 10 and configured to shape the pump light to form a laser spot with uniform light intensity distribution on a focal plane; the amplification cavity 30 is arranged at the output end of the laser shaping assembly 20 and comprises a dichroic mirror 31 and a first mirror 32 arranged oppositely, and a laser gain crystal 33 arranged between the dichroic mirror 31 and the first mirror 32; the shaped pump light is transmitted by the dichroic mirror 31 and focused on the laser gain crystal 33; and the picosecond laser seed source 40 is configured to emit seed light. The seed light is reflected multiple times between the dichroic mirror 31 and the first mirror 32, and is amplified by the laser gain crystal 33 multiple times to output laser light.

[0027] In the technical solution of the application, the amplification process of the picosecond laser is as follows: the pump source 10 emits pump light, the shaped pump light is transmitted by the dichroic mirror 31 and focused on the laser gain crystal 33 to form a laser spot with uniform light intensity on the laser gain crystal 33, and the pump light is absorbed by the laser gain crystal 33; at the same time, the picosecond laser seed source 40 emits seed light, the seed light is reflected multiple times between the dichroic mirror 31 and the first mirror 32, and the seed light passes through the laser gain crystal 33 each time to absorb the energy converted by the pump light, thereby realizing multiple amplification. After multiple amplification, the power of the seed light is significantly increased to form the final picosecond laser output.

[0028] It can be understood that the principle of laser amplification is that the pump light entering the laser gain crystal 33 causes the particles in the crystal to transition from a low energy level to a high energy level, and the seed light takes away the energy in the crystal to be amplified. In the application, the shaped pump light is incident on the laser gain crystal 33, and due to the uniform distribution of light intensity, the pump light can more uniformly excite the particles in the laser gain crystal, so that the energy distribution is uniform, thereby the seed light can more effectively extract the energy in the crystal when passing through the laser gain crystal 33 multiple times, without causing problems such as spot deformation and eccentricity, improving the laser efficiency and ensuring the stability of the beam quality. Moreover, the uniform light intensity of the pump light can make the heat distribution in the crystal uniform, so that the entire system is in a stable state.

[0029] In some embodiments, the pump source 10 is a semiconductor bar laser. The selection of the pump source 10 has higher stability, can convert more electrical energy into laser energy, and ensures the pumping effect. Moreover, the semiconductor bar laser has a relatively small size and a compact structure, and is convenient for integration and installation. Furthermore, by adjusting the composition and structure of the semiconductor material, the wavelength of the semiconductor bar laser can be adjusted, so as to match the absorption spectrum of different laser gain crystals 33 and improve the utilization rate of the pump light.

[0030] In some embodiments, the laser shaping assembly 20 includes a collimating mirror 21 and a beam homogenization module 22 arranged in sequence along the optical path. The pump light emitted by the semiconductor bar laser is shaped by the collimating mirror 21 and the beam homogenization module 22, and then focused on the laser gain crystal 33.

[0031] In this embodiment, when the pump light emitted by the semiconductor bar laser passes through the collimating mirror 21, the high-order Gaussian light in the fast-axis direction can be collimated into parallel light. Then, when the pump light passes through the beam homogenization module 22, the second-order super-Gaussian distribution in the slow-axis direction can be homogenized into flat-top light, so as to realize uniform distribution of light intensity. Finally, the pump light is focused on the laser gain crystal 33 to realize efficient pumping.

[0032] The collimating mirror 21 can be a convex lens and a concave mirror, and the curvature and position of the collimating mirror 21 are designed to form a parallel light beam after the pump light passes through the collimating mirror 21. The beam homogenization module 22 includes a double-row microlens array 221 and an integrating lens 222 arranged in sequence along the optical path. The double-row microlens array 221 is composed of two opposite microlens arrays. Each microlens array includes a plurality of microlens units arranged in an array. The microlens units in the two microlens arrays correspond one-to-one, and the one-to-one corresponding microlens units form a beam channel, and the channel length is equal to the focal length of the microlens unit. When the pump light passes through the double-row microlens array 221, the pump light is divided into a plurality of small beams in each beam channel, and finally enters the aperture of the integrating lens 222. The integrating lens 222 focuses and superimposes these small beams on the focal plane to form a light spot with uniform light intensity. That is, the pump light is focused on the laser gain crystal 33 to ensure that the beam forms a light spot with uniform light intensity on the laser gain crystal 33. Moreover, the integrating lens is a focusing lens, and is preferably a plano-convex lens. The plano-convex lens has excellent focusing performance and aberration correction ability, which helps to maintain the stability and consistency of the focused light spot, thereby improving the stability and quality of the laser output.

[0033] Referring to Figure 1As shown, in some embodiments, the amplification cavity 30 further comprises an incidence adjusting mirror 34 and an emission adjusting mirror 35, the incidence adjusting mirror 34 is used to adjust the incidence angle of the seed laser, and the emission adjusting mirror 35 is used to adjust the emission angle of the amplified laser; wherein the incidence adjusting mirror 34 and the emission adjusting mirror 35 cooperate to jointly adjust the number of times the seed laser passes through the laser gain crystal 33 in the amplification cavity 30.

[0034] In this embodiment, the main function of the incidence adjusting mirror 34 is to adjust the incidence angle of the seed laser. By adjusting the incidence angle, the propagation path of the seed laser in the amplification cavity 30 can be optimized, thereby realizing precise control of the laser amplification process. The emission adjusting mirror 35 is used to adjust the emission angle of the amplified laser. By adjusting the emission angle, it can be ensured that the amplified laser can propagate in the predetermined direction to meet the needs of subsequent applications. Among them, the incidence adjusting mirror 34 and the emission adjusting mirror 35 are both adjustable mirrors.

[0035] In actual application process, by accurately adjusting the position and angle of the mirror, it can be ensured that the seed laser passes through the crystal multiple times in the best path, thereby realizing the maximum amplification efficiency.

[0036] In some embodiments, the laser gain crystal 33 is in the shape of a strip.

[0037] In this embodiment, the strip-shaped crystal has a large heat dissipation area. Especially when the uppermost and lowermost surfaces are cooled, the temperature gradient in the internal width direction is approximately 0, and the temperature gradient in the thickness direction is approximately parabolic distribution, thereby helping to reduce the temperature of the laser medium and reduce the influence of thermal effects on the laser output. In addition, the strip-shaped crystal has a compact structure design, which is convenient for integration into a laser system. Therefore, its small volume also helps to reduce the complexity and cost of the entire laser system.

[0038] In some embodiments, the laser gain crystal 33 includes neodymium-doped yttrium vanadate (Nd:YVO4), neodymium-doped yttrium aluminum garnet (Nd:YAG), neodymium-doped yttrium lithium fluoride (Nd:YLF), and ytterbium-doped yttrium aluminum garnet (Yb:YAG). These are common laser gain crystals. When selecting a laser gain crystal, a comprehensive consideration can be made according to the specific application requirements, the characteristics of the pump light source, and the overall design of the system.

[0039] In summary, the picosecond laser proposed in this application can realize miniaturization in volume and can perform high-quality picosecond laser amplification through the above settings.

[0040] The above merely provides part or preferred embodiments of the present application, and neither the text nor the drawings can limit the scope of protection of the present application. Any equivalent structure variations made according to the contents of the present application and drawings, or direct / indirect application in other related technical fields shall fall within the scope of protection of the present application.

Claims

1. A picosecond laser, characterized in that, include: Pump source, used to emit pump light; A laser shaping component is disposed at the output end of the pump source and is used to shape the pump light to form a laser spot with uniform intensity distribution on the focal plane. An amplification cavity is disposed at the output end of the laser shaping component. The amplification cavity includes a dichroic mirror and a first reflecting mirror disposed opposite each other, and a laser gain crystal disposed between the two. The shaped pump light is transmitted through the dichroic mirror and focused onto the laser gain crystal. Picosecond laser seed source, used to emit seed laser; The seed laser is reflected multiple times between the dichroic mirror and the first reflector, and then amplified multiple times by the laser gain crystal before being output as laser.

2. The picosecond laser according to claim 1, characterized in that, The pump source is a semiconductor bar laser.

3. The picosecond laser according to claim 2, characterized in that, The laser shaping component includes a collimating lens and a beam homogenization module arranged sequentially along the optical path. The pump light emitted by the semiconductor bar laser is shaped by the collimating lens and the beam homogenization module and then focused onto the laser gain crystal.

4. The picosecond laser according to claim 3, characterized in that, The beam homogenization module includes a double-row microlens array and an integrating lens arranged sequentially along the optical path.

5. The picosecond laser according to claim 4, characterized in that, The integrating lens is a plano-convex focusing lens.

6. The picosecond laser according to claim 1, characterized in that, The amplification cavity also includes an incident adjustment mirror and an exit adjustment mirror. The incident adjustment mirror is used to adjust the incident angle of the seed laser, and the exit adjustment mirror is used to adjust the exit angle of the amplified laser. The incident adjustment mirror and the exit adjustment mirror work together to adjust the number of times the seed laser passes through the laser gain crystal within the amplification cavity.

7. The picosecond laser according to claim 6, characterized in that, The laser gain crystal is in the shape of a slab.

8. The picosecond laser according to claim 7, characterized in that, The laser gain crystal includes neodymium-doped yttrium vanadate, neodymium-doped yttrium aluminum garnet, neodymium-doped lithium fluoride yttrium, and ytterbium-doped yttrium aluminum garnet.

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