WO2020034803A1

WO2020034803A1 - Gain medium multiplexed thin disk hybrid amplification laser and laser output method therefor

Info

Publication number: WO2020034803A1
Application number: PCT/CN2019/096320
Authority: WO
Inventors: 陆俊; 于广礼; 丁建永
Original assignee: 南京先进激光技术研究院
Priority date: 2018-08-17
Filing date: 2019-07-17
Publication date: 2020-02-20
Also published as: CN110838667A

Abstract

A gain medium multiplexed thin disk hybrid amplification laser and laser output method therefor. The gain medium multiplexed thin disk hybrid amplification laser comprises: a seed laser (1) for injection of amplifier seed light. A laser beam enters a regenerative amplifier by sequentially passing through a first lens (2), a second lens (3), a first polarizer (4), a Faraday rotator (5), and a half-wave plate (6), and is oscillated and amplified in the regenerative amplifier and then enters a travelling wave amplifier after passing through the half-wave plate (6), the Faraday rotator (5), and the first polarizer (4); the travelling wave amplifier and the regenerative amplifier share a thin disk gain module.

Description

Gain medium multiplexed sheet hybrid amplification laser and laser output method thereof

Technical field

The invention relates to a thin-film laser amplifier, in particular to a regeneration and traveling wave hybrid amplification laser with gain medium multiplexing.

Background technique

Thin-film lasers are an important development direction of current high-average power lasers. The heat dissipation characteristics of laser media are an important factor affecting the development of high-power lasers. Thin-film lasers use crystals with a thickness of 100-200 μm as a gain medium. The diamond with the highest thermal conductivity is welded, so that the heat in the crystal can be efficiently transferred to the heat sink. In addition, under the cooling technology of the back surface and the flat top pump light, this structure can produce a perpendicular to the surface of the laser gain medium. Almost uniform axial one-dimensional heat flow, which can reduce the thermal lens effect and thermal deposition in the gain medium, so as to achieve high power laser output while maintaining high efficiency and high beam quality.

Thin-film laser amplifiers can be divided into thin-film regenerative amplifiers and thin-film traveling wave amplifiers according to their types: thin-film regenerative amplifiers mainly inject signal light into the cavity through polarization control, and then change the polarization state of the amplified laser when the laser energy reaches the expected value, and then pass The polarizer is led out of the cavity; the traveling wave amplifier controls the signal light with a certain energy through pulse transmission and images it on the crystal multiple times to complete the pulse power amplification.

For high-power thin-film laser amplifiers, the power amplification of laser pulses can be obtained through regenerative amplification or traveling wave amplification schemes. Among them, for the regenerative amplification type power amplifier, it has the advantages of high gain multiple and compact amplifier stage structure. According to the structure, the regenerative amplifier can be divided into standing wave regenerative amplifier and traveling wave regenerative amplifier. The limited extinction ratio of the device will introduce problems such as inter-stage feedback, which will affect the stability of the front-end laser; the latter avoids the problem of inter-stage feedback because the injected and derived light is not on a straight line. However, no matter what type of regenerative amplifier, in order to obtain high-power laser output, a larger-diameter electro-optic crystal is required to reduce the laser power density in the cavity. On the one hand, higher requirements are imposed on the crystal growth process; on the other hand, The design of ultra-high-voltage drivers also poses high challenges. In addition, the traveling wave amplifier can obtain higher power output without the need for excessive optical and electrical components. It has the advantages of simple structure and configuration, and does not introduce inter-stage feedback. However, due to the limitation of gain multiples, The signal light that needs to be injected has a certain energy, that is, one or more stages of amplifiers are required to pre-amplify the injected pulses before traveling wave amplification, which increases the complexity of the entire system to a certain extent.

paper

M,

J, Novák O, et al. Progress in kW-class picosecond thin-disk lasers development at the HiLASE [C] // Solid State Lasers XXV: Technology and Devices. International Society for Optics and Photonics, 2016, 9726: 972617, It is proposed to use the standing wave regeneration amplification and traveling wave regeneration amplification schemes to complete the pulse amplification. In order to obtain high-power amplified pulse output, the size of the electro-optic crystal needs to be about 12 * 12mm. For the traveling-wave regeneration amplifier, two-stage application of the electro-optic crystal is required. Half-wave voltage, which greatly increases the difficulty and cost of electrical design.

Paper Negel J, Voss A, Ahmed A, et al. 1.1 kW average output power from a thin-disk multipass amplifier for ultrashort lasers [J] .Optics letters, 2013, 38 (24): 5442-5445, It is proposed to use multi-path traveling wave amplification of the pulses amplified by the pre-amplification stage. This scheme can actually amplify the average laser power to the order of kilowatts. However, this configuration increases the complexity of the entire system.

Summary of the Invention

The technical problem mainly solved by the invention is to provide a thin-sheet hybrid amplifier laser with compact structure and high integrated light and light efficiency. To solve the above technical problems, a technical solution adopted by the present invention is:

A thin-film hybrid amplification laser with gain medium multiplexing includes:

Seed laser for injection of seed light into the amplifier;

The laser beam passes through a first lens, a second lens, a first polarizer, a Faraday rotator, and a half-wave plate into a regeneration amplifier in order, and is oscillated and amplified by the half-wave plate and the Faraday rotator in the regeneration amplifier. 2. The first polarizing plate enters a traveling wave amplifier, and the traveling wave amplifier and the regeneration amplifier share a sheet gain module.

In one embodiment, the regenerative amplifier is a standing wave regenerative amplifier or a traveling wave regenerative amplifier.

In one embodiment, the regenerative amplifier includes a second polarizer, a quarter wave plate, a photoelectric crystal, a second end mirror, a first folding mirror, a second folding mirror, a third folding mirror, and a sheet gain module. , The fourth folding mirror and the first end mirror.

In one embodiment, the traveling wave amplifier includes an optical isolator, a third lens, a fourth lens, a fifth folding mirror, a sixth folding mirror, a seventh folding mirror, and a sheet gain module shared with the regeneration amplifier. .

In one embodiment, the seed laser is a fiber picosecond, femtosecond mode-locked laser, solid picosecond, or femtosecond mode-locked laser.

A laser output method for a gain medium multiplexed sheet hybrid amplification laser as described above, including:

Output a laser beam from a seed laser;

In one of the embodiments, the oscillating amplification returned by the end mirror to the regeneration amplifier within the original path is:

Before the laser beam reaches the electro-optic crystal, a quarter voltage is applied across the electro-optic crystal, and after the laser beam travels back and forth between the quarter-wave plate and the electro-optic crystal, the laser beam The polarization state remains unchanged, oscillating back and forth within the regenerative amplifier multiple times, when the power reaches a maximum value, the voltage across the electro-optic crystal is turned off, and the laser beam light travels back and forth between the quarter wave plate and the The electro-optic crystal becomes p or s polarization, and then passes through the second polarizer.

In the above-mentioned gain medium multiplexed sheet hybrid amplification laser and its laser output method, the p (or s) polarized light emitted by the seed laser is collimated by the lens group, passes through the first thin film polarizer, and then passes through the Faraday rotator and A half-wave plate whose polarization state remains unchanged is still p (or s) polarization, and then passes through the second thin-film polarizer, and the seed light injected thereafter travels back and forth between the quarter-wave plate and the electro-optic crystal. After the voltage is not applied to the crystal, the pulse becomes s (or p) polarization after the round trip. It is reversed into the regenerative amplifier through a second thin film polarizer, and then the injected light passes through the folding mirror sheet crystal and the end mirror at one time. The pulse is injected at both ends of the electro-optic crystal. A quarter voltage is applied before reaching again, and the seed light injected thereafter is amplified back and forth in the cavity. When the pulse energy is large enough, the two-stage voltage of the electro-optic crystal is removed, and the pulse travels back and forth once again between the electro-optic crystal and the quarter-wave plate. When it becomes p (or s) polarization and passes through the second thin film polarizer, and then passes through the half-wave plate and Faraday rotator to become s (or p) polarization through the first thin film polarizer To a traveling wave amplifier. Before entering the traveling wave amplifier, the optical isolator and the beam expanding collimating lens group are used, and then the regenerated and amplified seed light is repeatedly hit on the laser crystal through multiple groups of folding mirrors to complete further traveling wave amplification. It has the characteristics of compact structure and high comprehensive light and optical efficiency: the regenerative amplifier and the traveling wave amplifier share a set of thin-film gain modules, and can obtain higher laser power output in the case of using smaller aperture electro-optic crystals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a thin-film hybrid amplification laser with gain medium multiplexing according to an embodiment.

In the picture, 0-sheet gain module, 1-picosecond or femtosecond laser, 2-first lens, 3-second lens, 4-first polarizer, 5-Faraday rotator, 6-half wave plate, 7 -The second polarizer, 8-quarter wave plate, 9-electro-optic crystal, 10-second end mirror, 11-first folding mirror, 12-second folding mirror, 13-third folding mirror, 14- Fourth folding mirror, 15-first end mirror, 16-optical isolator, 17-third lens, 18-fourth lens, 19-fifth folding mirror, 20-sixth folding mirror, 21-seventh folding mirror .

detailed description

Please refer to FIG. 1, a gain medium multiplexed sheet hybrid amplification laser according to an embodiment of the present invention includes: a seed laser 1 for injecting seed light of an amplifier; a first lens 2, a second lens 3, and a first polarization Plate 4, Faraday rotator 5, half wave plate 6, second polarizer 7, quarter wave plate 8, electro-optic crystal 9, second end mirror 10, first folding mirror 11, second folding mirror 12, Tri-folding mirror 13, fourth folding mirror 14, first end mirror 15, 16-optical isolator 16, third lens 17, fourth lens 18, fifth folding mirror 19, sixth folding mirror 20, seventh folding mirror twenty one.

The laser beam passes through the first lens 2, the second lens 3, the first polarizer 4, the Faraday rotator 5, the half-wave plate 6, and the second polarizer 7 into the regeneration amplifier, and then passes through the first folding mirror 11 and the second folding The mirror 12 and the third folding mirror 13 are reflected to the thin-film gain module 0, and then reflected to the first end mirror 15 through the fourth folding mirror 14 and returned to the regeneration amplifier via the original end mirror to oscillate and pass through the second. The polarizing plate 7, the half-wave plate 6, the Faraday rotator 5, and the first polarizing plate 4 pass through the optical isolation 16 and the third lens 17, the fourth lens 18, and then pass through the fifth folding mirror 19 and the sixth folding mirror 20. And the seventh folding mirror 21 sequentially staggers the injected laser beam to form a plurality of laser beams and reflects them to the sheet gain module 0, and the amplified multiple laser beams are emitted from the sixth folding mirror 20 and the seventh folding mirror 21.

Specifically, in one embodiment, the sheet gain module is a sheet crystal of a pump module.

Specifically, in one embodiment, the seed laser is a fiber picosecond, femtosecond mode-locked laser, solid picosecond or femtosecond mode-locked fiber with a repetition frequency of 20-80MHz, an average power of 10-100mW, a pulse width of 10ps, and a center wavelength of 1030nm. Laser.

Specifically, in one embodiment, the regenerative amplifier is a standing wave type regenerative amplifier or a traveling wave regenerative amplifier.

Specifically, in an embodiment, the regenerative amplifier includes a quarter-wave plate 8, a photoelectric crystal 9, a second end mirror 10, a first folding mirror 11, a second folding mirror 12, a third folding mirror 13, and a fourth Folding mirror 14, first end mirror 15 and sheet gain module 0.

Specifically, in an embodiment, the traveling wave amplifier includes an optical isolator 16, a third lens 17, a fourth lens 18, a fifth folding mirror 19, a sixth folding mirror 20, a seventh folding mirror 21, and a common use with a regenerative amplifier. The slice gain module 0.

Specifically, in an embodiment, the first lens 2, the second lens 3, the third lens 17, and the fourth lens 18 are collimating lenses.

Specifically, in one embodiment, the first polarizing plate 4 and the second polarizing plate 7 are wave plate polarizing plates.

Specifically, in one embodiment, the working process of the thin-film hybrid amplification laser with multiplexed gain medium is as follows: the pulses after the laser beam menu output by the seed laser 1 pass through the first lens 2 and the second lens 3 and pass through the first lens. After passing through the Faraday rotator, the polarization direction is deflected by 45 °, and after passing through the half-wave plate 6, the polarization direction becomes p (or s) polarization again and passes through the second polarization plate 7. Then it passes through the quarter-wave plate 8 and the electro-optic crystal 9 in this order. At this time, the electro-optic crystal has no voltage applied. After transmission, the seed light polarization state changes from p (or s) polarization to circular polarization, and then returns through the second end mirror 10 It then passes through the electro-optic crystal 9 and the quarter-wave plate 8 again. At this time, the polarization state of the seed light becomes s (or p) polarization, and is then reflected by the second polarizer 7 into the regenerative amplifier. Then, the first folding mirror 11, the second folding mirror 12, and the third folding mirror 13 reflect the pulse expanded beam to the surface of the sheet gain module 0, and then the seed light reflected by the sheet gain module 0 is reflected by the fourth folding mirror 14 to the first Mirror 15 on one end. Then the first end mirror 15 returns the signal light along the original path. When the signal light reaches the electro-optic crystal 9 again, a quarter voltage is applied across the electro-optic crystal 9 so that the returned seed light returns to the quarter-wave plate again. After 8 and the electro-optic crystal 9 once, the laser polarization state remains unchanged and is still s (or p) polarization, so the seed light will oscillate back and forth in the regeneration cavity multiple times. When the power reaches a maximum value, the electro-optic crystal 9 is turned off Voltage of the seed, the seed light becomes p (or s) polarization after going back and forth between the quarter-wave plate 8 and the electro-optic crystal 9, and then passes through the second polarizing plate 7 and the half-wave plate 6, and the amplified polarization direction of the seed light The light is deflected by 45 degrees, and after passing through the Faraday rotator 5, the seed light becomes s (or p) polarization again, and then passes through the first polarizer 4 reflector. Thereafter, the amplified seed light passes through the optical isolator 16 and the third lens 17 and the fourth lens 18 in order, and then the injected seed light is staggered by the fifth folding mirror 19, the sixth folding mirror 20, and the seventh folding mirror 21 in this order. After hitting the surface of the thin-film gain module 0 multiple times, the amplified laser pulse is emitted from the middle of the sixth folding mirror 20 and the seventh folding mirror 21.

S110. A laser pulse is output from the seed laser 1.

S120. The polarization beam splitting module divides the laser pulse into two laser beams;

S130, the laser beam passes through the first lens 2, the second lens 3, the first polarizer 4, the Faraday rotator 5, the half-wave plate 6, and the second polarizer 7 enters the regeneration amplifier, and then passes through the first folding mirror 11, The second folding mirror 12 and the third folding mirror 13 are reflected to the thin-film gain module 0, and then reflected to the first end mirror 15 through the fourth folding mirror 14 and return to the regeneration amplifier through the original end mirror 15 to oscillate. After magnification, it passes through the second polarizer 7, half-wave plate 6, Faraday rotator 5, and first polarizer 4, and then passes through the optical isolator 16, the third lens 17, and the fourth lens 18, and then passes through the first folding mirror 19. The second folding mirror 20 and the third folding mirror 21 sequentially stagger the injected laser beams to form a plurality of laser beams and all of them are reflected to the sheet gain module 0. The amplified multiple laser beams are folded from the second folding mirror 20 and the third Shot in the mirror 21.

Specifically, in one embodiment, the oscillation is amplified by the first end mirror 15 and returned to the regenerative amplifier through the original path:

Before the laser beam reaches the electro-optic crystal 9, a quarter voltage is applied across the electro-optic crystal 9, and after the laser beam travels back and forth between the quarter-wave plate 8 and the electro-optic crystal 9, the polarization state of the laser beam remains unchanged, and the regeneration The amplifier oscillates back and forth multiple times. When the power reaches the maximum value, the voltage across the electro-optic crystal 9 is turned off. The laser beam light passes back and forth between the quarter-wave plate 8 and the electro-optic crystal 9 and becomes p or s polarization. The second polarizing plate 7 is described, and continues to go backward.

Specifically, the structure of the thin-film hybrid amplification laser with multiplexed gain medium has been described in detail above, and is not repeated here.

Specifically, in one embodiment, the laser output method of the thin-film hybrid amplifier laser with gain medium multiplexing is: the pulses after the laser beam menu output by the seed laser 1 are collimated by the first lens 2 and the second lens 3 and transmitted through the first lens 2. A polarizing plate 4 passes through a Faraday rotator, and then the polarization direction is deflected by 45 °. After passing through the half-wave plate 6, the polarization direction becomes p (or s) polarization again and passes through the second polarizing plate 7. Then it passes through the quarter-wave plate 8 and the electro-optic crystal 9 in this order. At this time, the electro-optic crystal has no voltage applied. After transmission, the seed light polarization state changes from p (or s) polarization to circular polarization, and then returns through the second end mirror 10 It then passes through the electro-optic crystal 9 and the quarter-wave plate 8 again. At this time, the polarization state of the seed light becomes s (or p) polarization, and is then reflected by the second polarizer 7 into the regenerative amplifier. Then 11-first folding mirror, 12-second folding mirror, and 13-third folding mirror reflect the pulsed beam expansion to the surface of the thin-film gain module 0, and then the seed light reflected by the thin-film gain module 0 passes through the fourth folding mirror 14 Reflected on the first end mirror 15. Then the first end mirror 15 returns the signal light along the original path. When the signal light reaches the electro-optic crystal 9 again, a quarter voltage is applied across the electro-optic crystal 9 so that the returned seed light returns to the quarter-wave plate again. After 8 and the electro-optic crystal 9 once, the laser polarization state remains unchanged and is still s (or p) polarization, so that the seed light will oscillate back and forth in the regeneration cavity multiple times. When the power reaches a maximum value, the electro-optic crystal 9 is turned off. Voltage of the seed, the seed light becomes p (or s) polarization after going back and forth between the quarter-wave plate 8 and the electro-optic crystal 9, and then passes through the second polarizing plate 7 and the half-wave plate 6, and the amplified polarization direction of the seed light The light is deflected by 45 degrees, and after passing through the Faraday rotator 5, the seed light becomes s (or p) polarization again, and then passes through the first polarizer 4 reflector. Thereafter, the amplified seed light passes through the optical isolator 16 and the third lens 17 and the fourth lens 18 in order, and then the injected seed light is staggered by the fifth folding mirror 19, the sixth folding mirror 20, and the seventh folding mirror 21 in this order. After hitting the surface of the thin-film gain module 0 multiple times, the amplified laser pulse is emitted from the middle of the sixth folding mirror 20 and the seventh folding mirror 21.

In the above-mentioned gain medium multiplexed sheet hybrid amplification laser and its laser output method, the p (or s) polarized light emitted by the seed laser is collimated by the lens group, passes through the first thin film polarizer, and then passes through the Faraday rotator and A half-wave plate whose polarization state remains unchanged is still p (or s) polarization, and then passes through the second thin-film polarizer, and the seed light injected thereafter travels back and forth between the quarter-wave plate and the electro-optic crystal. After the voltage is not applied to the crystal, the pulse becomes s (or p) polarization after the round trip. It is reversed into the regenerative amplifier through a second thin film polarizer, and then the injected light passes through the folding mirror sheet crystal and the end mirror at one time. The pulse is injected at both ends of the electro-optic crystal. A quarter voltage is applied before reaching again, and the seed light injected thereafter is amplified back and forth in the cavity. When the pulse energy is large enough, the two-stage voltage of the electro-optic crystal is removed, and the pulse travels back and forth once again between the electro-optic crystal and the quarter-wave plate. When it becomes p (or s) polarization and passes through the second thin film polarizer, and then passes through the half-wave plate and Faraday rotator to become s (or p) polarization through the first thin film polarizer To a traveling wave amplifier. Before entering the traveling wave amplifier, the optical isolator and the beam expanding collimating lens group are used, and then the regenerated and amplified seed light is hit on the laser crystal multiple times through multiple groups of folding mirrors to complete further traveling wave amplification. It has the characteristics of compact structure and high comprehensive light and optical efficiency: the regenerative amplifier and traveling wave amplifier share a set of thin-film gain modules, and can obtain higher laser power output in the case of using smaller aperture electro-optic crystals.

The above is only an embodiment of the present invention, and thus does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description and drawings of the present invention, or directly or indirectly used in other related technical fields, All the same are included in the patent protection scope of the present invention.

Claims

A thin-film hybrid amplification laser with gain medium multiplexing, which includes:

Seed laser for injection of seed light into the amplifier;

The laser beam passes through a first lens, a second lens, a first polarizer, a Faraday rotator, and a half-wave plate into a regeneration amplifier in order, and is oscillated and amplified by the half-wave plate and the Faraday rotator in the regeneration amplifier. 2. The first polarizing plate enters a traveling wave amplifier, and the traveling wave amplifier and the regeneration amplifier share a sheet gain module.
The thin-film hybrid amplifier laser for gain medium multiplexing according to claim 1, wherein the regenerative amplifier is a standing wave type regenerative amplifier or a traveling wave regenerative amplifier.
The thin-film hybrid amplification laser with gain medium multiplexing according to claim 1, wherein the regeneration amplifier comprises a second polarizer, a quarter-wave plate, a photoelectric crystal, a second end mirror, and a first folding mirror , A second folding mirror, a third folding mirror, a sheet gain module, a fourth folding mirror and a first end mirror.
The thin-film hybrid amplification laser for gain medium multiplexing according to claim 1, wherein the traveling wave amplifier comprises an optical isolator, a third lens, a fourth lens, a fifth folding mirror, a sixth folding mirror, a first A seven-fold mirror and a sheet gain module shared with the regeneration amplifier.
The thin-film hybrid amplification laser for gain medium multiplexing according to claim 1, wherein the seed laser is a fiber picosecond, femtosecond mode-locked laser, solid picosecond, or femtosecond mode-locked laser.
A laser output method for a gain medium multiplexed thin-film hybrid amplification laser according to any one of claims 1 to 5, comprising:

Output a laser beam from a seed laser;

The laser beam passes through a first lens, a second lens, a first polarizer, a Faraday rotator, and a half-wave plate into a regeneration amplifier in order, and is oscillated and amplified by the half-wave plate and the Faraday rotator in the regeneration amplifier. 2. The first polarizing plate enters a traveling wave amplifier, and the traveling wave amplifier and the regeneration amplifier share a sheet gain module.
The laser output method of the gain medium multiplexed sheet hybrid amplification laser according to claim 6, wherein the regeneration amplifier comprises a second polarizer, a quarter wave plate, a photoelectric crystal, and a second The end mirror, the first folding mirror, the second folding mirror, the third folding mirror, the sheet gain module, the fourth folding mirror and the first end mirror.
The laser output method of the gain medium multiplexed thin-film hybrid amplification laser according to claim 7, wherein the oscillation amplification returned by the end mirror to the regeneration amplifier in the original path is:

Before the laser beam reaches the electro-optic crystal, a quarter voltage is applied across the electro-optic crystal, and after the laser beam travels back and forth between the quarter-wave plate and the electro-optic crystal, the laser beam The polarization state remains unchanged, oscillating back and forth within the regenerative amplifier multiple times, when the power reaches a maximum value, the voltage across the electro-optic crystal is turned off, and the laser beam light travels back and forth between the quarter wave plate and the The electro-optic crystal becomes p or s polarization, and then passes through the second polarizer.
The laser output method of the gain medium multiplexed thin-film hybrid amplification laser according to claim 6, wherein the traveling wave amplifier comprises an optical isolator, a third lens, a fourth lens, and a fifth folding mirror , A sixth folding mirror, a seventh folding mirror, and a sheet gain module shared with the regeneration amplifier.
The laser output method of the gain medium multiplexed sheet hybrid amplification laser according to claim 6, wherein the regeneration amplifier is a standing-wave regeneration amplifier or a traveling-wave regeneration amplifier.