Nonlinear beam-combining high-average-power ultra-short and ultra-strong solid laser

Abstract

A nonlinear beam-combining high-average-power ultra-short and ultra-strong solid laser comprises a pump light fiber laser, a signal light fiber laser, a pump light beam, a signal light beam, a beam-combining lens, a nonlinear crystal, idler frequency light and amplified signal light. Based on a multi-beam fiber laser pumping nonlinear crystal meeting a phase matching angle, multi-path pumping light with high average power amplifies single ultrafast signal light at the same time, and nonlinear superposition of multi-beam fiber laser energy is obtained while optical parametric amplification is achieved, so that ultrashort and ultrastrong laser amplification output with high average power is obtained. According to the invention, the multi-beam high-average-power fiber laser is used as a pumping source, and the difference between the wavelength of signal light amplified by nonlinear parameters and the wavelength of pumping light is small, so that the system has the advantages of low quantum loss, high conversion efficiency, insensitivity to temperature, high average power and the like, and is a new technology for realizing high-average-power (TW-PW) ultra-short and ultra-strong laser.

Description

Technical Field

[0001] The present invention relates to an ultrashort and ultra-intense laser with high average power, in particular to an ultrashort and ultra-intense (TW-PW level peak power) solid laser based on optical parametric amplification (OPA) pumped by a multi-beam fiber laser array. The parametric amplified ultrashort and ultra-intense solid laser improves amplification efficiency by absorbing idle light, and improves average power by pumping by a multi-beam fiber laser array. Meanwhile, wavelength tuning can be realized, and a high repetition rate 100fs level pulse laser with an average power greater than 100W can be output. Background Art

[0002] At present, the ultrashort and ultra-intense (PW-level peak power) lasers that generate high average power mainly use energy-level chirped pulse amplification technology (CPA) and nonlinear parametric chirped pulse amplification technology (OPCPA). Although CPA performs well in increasing peak power, it is difficult to achieve high average power output due to the influence of thermal effects (caused by quantum loss). Although parametric amplification technology is not affected by thermal effects, it is difficult to obtain high amplification efficiency because it needs to meet phase matching conditions, and laser amplification is very sensitive to parameters such as temperature and angle, resulting in poor stability. Quasi-parametric amplification technology can achieve high energy conversion efficiency, but the maximum average power is still limited by the average power of a single pump beam, and it is difficult to achieve a significant breakthrough in the short term.

[0003] In recent years, although multicolor pumping technology has achieved wide-bandwidth parametric laser amplification and power enhancement to a certain extent, the inherent problems of low efficiency and poor stability of conventional parametric amplification technology have not been fundamentally solved. The system is still highly sensitive to temperature and angle, which makes the system stability easily affected by the external environment and makes it difficult to achieve long-term stable high average power output.

[0004] At present, the field of ultrashort and ultra-intense laser technology needs to take into account high energy conversion efficiency and high beam quality while pursuing high average power output. This goal still faces many technical difficulties and challenges. How to overcome the limitations of existing technologies and achieve efficient, stable, and high-power ultrashort and ultra-intense laser output is a key issue that needs to be solved in this field. Summary of the invention

[0005] In view of the deficiencies of the above-mentioned prior art, the present invention combines high average power fiber lasers and very multi-beam laser pumping technology and nonlinear quasi-parametric amplification technology to provide a high average power ultrashort ultra-strong solid laser based on quasi-parametric amplification of very multi-beam fiber laser array pumping. The laser adopts nonlinear frequency conversion to convert multiple pump beams into a single signal beam, which is a new type of nonlinear beam combining technology. It can not only obtain high average power signal light, but also maintain high energy conversion efficiency by absorbing idle frequency light. At the same time, the amplified single signal light beam has high beam quality, and the amplification efficiency and amplification bandwidth (thereby adjusting the pulse width) can be changed by adjusting the angle between the pump beam and the signal light. In addition, the technology integrates multiple pump beams into a single-stage amplifier, so that the system structure is simple and can be applied to the fields of laser processing, high-order harmonic generation, laser particle acceleration, etc.

[0006] The present invention is achieved through the following technical solutions:

[0007] A high average power quasi-parametric amplified ultrashort ultra-strong solid laser based on a multi-beam fiber laser array pumping, characterized in that it comprises a pump light fiber laser, a signal light fiber laser, a pump light beam, a signal light beam, a beam combining lens, a nonlinear crystal, an idler light and an amplified signal light, and the connection relationship of the above components is as follows:

[0008] The pump light fiber laser is connected to the optical pump light beam, the signal light fiber laser is connected to the signal light beam, the pump light beam and the signal light beam are coupled into the nonlinear crystal through the beam combining lens, the pump light beam and the signal light beam are time synchronized and spatially overlapped in the nonlinear crystal, the nonlinear crystal amplifies the signal light beam and generates the idle light at the same time, the nonlinear crystal absorbs the idle light, and the nonlinear crystal amplifies the signal light and then outputs the amplified signal light.

[0009] The pump light fiber laser is a high-power ps fiber laser with a central wavelength of 1030nm, an output fiber core diameter of 30 / 250μm, a numerical aperture of 0.06 / 0.46, an adjustable pulse width of 1-10ps, and a maximum output average power of more than 50W.

[0010] The signal light fiber laser is a high average power femtosecond fiber laser with a central wavelength of 1300nm, a fiber core diameter of 30 / 250μm, a numerical aperture of 0.06 / 0.46, a maximum output power greater than 5W, and a laser pulse width of the order of 100fs.

[0011] The pump beams are multiple overlapping 1-micron fiber lasers, each of which is arranged approximately in parallel. The divergence characteristics of the pump beams are determined by the gain fiber core structure parameters of the pump fiber laser (core diameter is 30 μm, numerical aperture is 0.06).

[0012] The signal beam is a femtosecond laser with a central wavelength of 1.3 μm. There is a certain angle between the signal beam and the pump beam to meet the phase matching condition. The signal beam and the pump beam have a high overlap factor.

[0013] The beam combining lens is a quartz double convex lens, and both sides of the lens are coated with 1 micron and 1.3 micron anti-reflection films. The focal length of the lens is 200 mm and the diameter is 50 mm.

[0014] The linear crystal is a YCOB crystal, the incident end of the crystal is coated with 1 micron and 1.3 micron anti-reflection films, and the output end is coated with a 1.3 micron anti-reflection film. At the same time, the YCOB crystal is doped with specific ions to achieve efficient absorption of idle frequency light of a specific wavelength.

[0015] The idler light is generated by parametric amplification of a YCOB nonlinear crystal, and its wavelength is determined by the wavelength of the signal light, the pump light and energy conservation. In this example, the idler light wavelength is 4.96 μm, and the idler light is efficiently absorbed by the ion-doped YCOB crystal.

[0016] The amplified signal light is the signal light amplified by nonlinear crystal parameters, and its wavelength is the same as the injected 1.3μm signal light. The signal light amplification factor is determined by the pump light intensity, the injected signal light intensity, the nonlinear coefficient of the nonlinear crystal, the dissipation coefficient of the idler light, the length of the nonlinear crystal and other parameters.

[0017] Compared with the prior art, the technical advantages of the present invention are:

[0018] 1) Using multiple pump lasers to array-pump nonlinear crystals to achieve nonlinear laser beam combining can not only significantly improve the average power of laser parametric amplification, but also only requires one stage of amplification, and the system structure is simple;

[0019] 2) The quasi-parametric amplification technology that absorbs idle light is used to suppress the energy backflow during the parametric amplification process, which is beneficial to improving the energy conversion efficiency. In addition, this technology has the advantage of being temperature-insensitive and can achieve high average power and high stability of parametric amplified laser output. It is a new technology with great potential for increasing the average power of ultrashort and ultra-intense lasers.

[0020] 3) By adjusting the angle, time delay and spatial overlap factor between the pump light and the signal light, high-efficiency and high-average-power signal light parametric amplification can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the ultrashort and ultra-strong solid laser based on high average power quasi-parametric amplification pumped by a multi-beam fiber laser array of the present invention.

[0022] In the figure: pump light fiber laser 1, signal light fiber laser 2, pump beam 3, signal beam 4, beam combining lens 5, nonlinear crystal 6, idler light 7, signal light 8 DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0024] Figure 1 It is a schematic diagram of the optical path of the ultrashort ultra-strong solid laser with high average power quasi-parametric amplification based on a very large number of fiber laser arrays pumped by the present invention. As can be seen from the figure, the ultrashort ultra-strong solid laser with high average power quasi-parametric amplification based on a very large number of fiber laser arrays pumped by the present invention adopts a high average power ps fiber laser as a pump light fiber laser 1, and also includes a signal light fiber laser 2, a pump light beam 3, a signal light beam 4, a beam combining lens 5, a nonlinear crystal 6, an idler light 7 and an amplified signal light 8. The working principle of the present invention is as follows:

[0025] The pump beam 3 generated by the multi-channel pump light fiber laser 1 and the signal beam 4 generated by the signal light fiber laser 2 are coupled into the nonlinear crystal 6 through the beam combining lens 5. The nonlinear crystal 6 is polarized after being stimulated by the pump beam 3. When certain phase matching conditions are met (while ensuring the time synchronization and spatial overlap of the pump beam and the signal beam), the signal beam 4 is amplified, and the energy is transferred from the multi-channel pump beam 3 to the signal beam 4, generating amplified signal light 8 and idler light 7. The idler light 7 can be absorbed by doping different ions in the nonlinear crystal YCOB to improve the energy conversion efficiency. At the same time, the amplification efficiency is improved by adjusting the angle, time delay and spatial overlap factor of the pump beam 3 and the signal beam 4, and high-efficiency and high-average-power signal light parametric amplification is achieved.

[0026] Pump light and signal light configuration :The pump light fiber laser is a high-power ps fiber laser with a central wavelength of 1030nm, an output fiber core diameter of 30 / 250μm, a numerical aperture of 0.06 / 0.46, an adjustable pulse width, and a maximum output average power of more than 50W.

[0027] The signal light fiber laser is a high average power femtosecond fiber laser with a central wavelength of 1300nm, a fiber core diameter of 30 / 250μm, a numerical aperture of 0.06 / 0.46, a maximum output power greater than 5W, and a laser pulse width of the order of 100fs.

[0028] Beam combining and nonlinear amplification :The pump beam is a multiple beam of overlapping 1-micron fiber lasers, which are coupled into a nonlinear crystal (YCOB crystal, doped with specific ions to efficiently absorb idler light) through a beam combining lens (quartz biconvex lens, coated with 1-micron and 1.3-micron anti-reflection films). The signal beam and the pump beam are synchronized in time and overlapped in space in the nonlinear crystal, meeting the phase matching conditions, and realizing parametric amplification of the signal light.

[0029] Idler Light Processing and Energy Conversion : The idler light is generated by the parametric amplification process, and its wavelength is determined by the signal light, the pump light wavelength and the energy conservation. In this embodiment, it is 4.96μm, and is efficiently absorbed by the ion-doped YCOB crystal, thereby improving the energy conversion efficiency.

[0030] Amplify signal light output : The wavelength of the amplified signal light is the same as the injected 1.3μm signal light, and the amplification factor is determined by the pump light intensity, the injected signal light intensity, the nonlinear coefficient of the nonlinear crystal, the dissipation coefficient of the idler light, the length of the nonlinear crystal and other parameters.

Claims

1. A nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser, characterized in that: include: A pump light fiber laser is used to generate multiple overlapping pump lights; A signal light fiber laser is used to generate signal light; A beam combining lens, used for coupling the pump light and the signal light into a nonlinear crystal; A nonlinear crystal, wherein the pump light and the signal light are time-synchronized and spatially overlapped in the nonlinear crystal, and when a phase matching condition is satisfied, the signal light is amplified and idler light is generated simultaneously; The wavelength of the amplified signal light is the same as the wavelength of the injected signal light, and the amplification factor is comprehensively determined by the intensity of the pump light, the intensity of the injected signal light, the nonlinear coefficient of the nonlinear crystal, the dissipation coefficient of the idler light, and the length parameter of the nonlinear crystal.

2. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to claim 1, characterized in that: The pump light fiber laser has a central wavelength of 1030nm, a fiber core diameter of 30 / 250μm, a numerical aperture of 0.06 / 0.46, a maximum output power greater than 10W, and a laser pulse width of 1-10ps.

3. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to claim 1, characterized in that: The signal light fiber laser has a central wavelength of 1300 nm, a fiber core diameter of 30 / 250 μm, a numerical aperture of 0.06 / 0.46, a maximum output power greater than 5 W, and a laser pulse width of the order of 100 fs.

4. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to claim 1, characterized in that: The pump beams are multiple overlapping 1-micron fiber lasers, each pump beam is arranged approximately in parallel, and the divergence characteristics of the pump beams are determined by the gain fiber core structure parameters of the pump fiber laser, with a core diameter of 30 μm and a numerical aperture of 0.

06.

5. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to claim 1, characterized in that: There is a certain angle between the signal light and the pump light to meet the phase matching condition of optical parametric amplification, and the signal light beam and the pump light beam have an overlap factor greater than 0.

9.

6. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to claim 1, characterized in that: The beam combining lens is a quartz double convex lens, and the two sides of the lens are coated with 1 micron and 1.3 micron anti-reflection films. The focal length of the lens is 200 mm and the diameter is 50 mm.

7. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to claim 1, characterized in that: The nonlinear crystal is a YCOB crystal, the incident end face is coated with 1 micron and 1.3 micron anti-reflection films, and the output end is coated with a 1.3 micron anti-reflection film.

8. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to claim 1, characterized in that: The nonlinear crystal achieves efficient absorption of idle frequency light of a specific wavelength by doping specific ions.

9. The nonlinear beam-combined high average power ultrashort ultra-intense solid-state laser according to any one of claims 1 to 8, characterized in that: It also includes a control system for controlling the pump light fiber laser and the signal light fiber laser to synchronize the pump light and overlap the signal light in time and space to meet the phase matching condition.

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