Thin-film dual-pulse-width output laser and laser output method

Abstract

The present invention provides a thin-film dual-pulse-width output laser, comprising: a femtosecond laser; a polarization beam splitting module for splitting the laser pulses output by the femtosecond laser into two laser beams; one of the laser beams is sequentially introduced into a first regenerative amplifier through a first reflector, a first thin-film polarizer, a first Faraday rotator, a first half-wave plate and a first polarizer, oscillated and amplified therein, and then output after dispersion compensation by a first dispersion grating; the other laser beam is broadened to 2.7 ps by a second chirped volume Bragg grating, and then sequentially introduced into a second regenerative amplifier through a second reflector, a second thin-film polarizer, a second Faraday rotator, a second half-wave plate and a second polarizer, oscillated and amplified therein, and then output after dispersion compensation by a second dispersion grating. A laser output method is also provided. Dual-pulse-width lasers can be output simultaneously in the above device and method.

Description

Technical Field

[0001] The present invention relates to a thin disk laser amplifier, and particularly to a thin disk dual pulse width output laser. Background Art

[0002] With the development of the laser processing industry, ultrafast lasers play an increasingly important role in the industrial and scientific research fields. For some applications such as pump-probe and LIBS, it is necessary to use a pre-laser to interact with the target material, and then after a certain delay, the main laser interacts with it again. This poses certain requirements for the laser light source, requiring it to generate laser pulse outputs of two different pulses, and the delay between the two is adjustable.

[0003] Common high-power picosecond laser amplifiers include the INNOSLAB configuration, the rod-shaped Nd:YVO4 configuration, and the thin disk configuration. The basic idea is to first use a solid or fiber mode-locked laser as a seed and inject it into the subsequent amplifier, and the amplification stage uses a regenerative or traveling-wave amplification structure to amplify to 100W or higher power. Femtosecond lasers are divided into two types with pulse widths of 20 - 30fs and 300 - 900fs. The former has a narrower pulse width and requires a titanium sapphire with a wider gain bandwidth as the gain medium. Since titanium sapphire is generally in a bulk structure, its average power is generally low; while for the latter, due to the wider pulse width, the requirement for the gain bandwidth of the gain medium is lower, and generally Yb:YAG / Yb:KYW / Yb:KGW thin disk crystals can be used as the gain medium. Although the output pulse width is wider, the output power can be higher. For a dual pulse width laser, a common method is to use a femtosecond seed source and inject it into a femtosecond amplifier. After amplification, the laser is divided into two paths using a beam splitter, and then dispersion control is performed on the two beams of pulses respectively to obtain outputs of two pulse widths. This method generally generates a lower laser power.

[0004] Patent CN201075571Y proposed a dual pulse output laser with a Q-switching circuit switching scheme. When using a long pulse width drive circuit, a longer Q-switching pulse output can be obtained, and when switching to a short pulse width drive circuit, a shorter Q-switching pulse output can be obtained. This scheme can obtain laser pulse outputs with two pulse widths of several nanoseconds and several hundred nanoseconds, but it cannot output two pulse widths of laser simultaneously. Summary of the Invention

[0005] The main technical problem to be solved by the present invention is to provide a thin disk dual pulse width output laser that can output dual pulse widths simultaneously. To solve the above technical problem, a technical solution adopted by the present invention is:

[0006] A thin disk dual pulse width output laser, characterized by comprising:

[0007] A femtosecond laser;

[0008] A polarization beam splitting module for splitting the laser pulses output by the femtosecond laser into two laser beams;

[0009] One of the laser beams is sequentially introduced into the first regenerative amplifier through a first reflecting mirror, a first thin film polarizer, a first Faraday rotator, a first half-wave plate, and a first polarizer, oscillated and amplified, and then output as hundred-femtosecond laser after dispersion compensation by a first dispersion grating; the other laser beam is broadened by a second chirped volume Bragg grating and then sequentially introduced into the second regenerative amplifier through a second reflecting mirror, a second thin film polarizer, a second Faraday rotator, a second half-wave plate, and a second polarizer, oscillated and amplified, and then output as picosecond laser after dispersion compensation by a second dispersion grating.

[0010] In one embodiment, the first regenerative amplifier and the second regenerative amplifier are standing-wave regenerative amplifiers, traveling-wave regenerative amplifiers, or traveling-wave amplifiers.

[0011] In one embodiment, the first regenerative amplifier includes a first end mirror, a first electro-optic crystal, a first quarter-wave plate, the first polarizer, a third reflecting mirror, a fourth reflecting mirror, a thin disk gain module, a fifth reflecting mirror, and a second end mirror.

[0012] In one embodiment, the second regenerative amplifier includes a third end mirror, a second electro-optic crystal, a second quarter-wave plate, the second polarizer, a sixth reflecting mirror, and a fourth end mirror. The second regenerative amplifier shares the fourth reflecting mirror, the thin disk gain module, and the fifth reflecting mirror with the first regenerative amplifier.

[0013] In one embodiment, the thin disk gain module is a Yb:YAG thin disk crystal, a Yb:KGW thin disk crystal, a Yb:KYW thin disk crystal, or a titanium sapphire thin disk crystal.

[0014] In one embodiment, the first dispersion grating and the second dispersion grating are chirped volume Bragg gratings, CFBGs, reflective gold gratings, or transmissive dielectric film gratings.

[0015] In one embodiment, the repetition rate of the femtosecond laser is 10 - 100 MHz, the maximum average power is 5 - 50 mW, the pulse width is 100 - 800 fs, and the central wavelength is 1030 nm.

[0016] A laser output method for a thin disk dual-pulse-width output laser as described above, including:

[0017] Outputting laser pulses from a femtosecond laser;

[0018] The polarization beam splitting module splits the laser pulses into two laser beams;

[0019] One of the laser beams passes through the first mirror, the first thin-film polarizer, the first Faraday rotator, the first half-wave plate, and the first polarizer in sequence, and then passes through the first regenerative amplifier for in-oscillation amplification, and is output after dispersion compensation by the first dispersion grating;

[0020] The other laser beam is broadened by the second chirped volume Bragg grating, and then passes through the second mirror, the second thin-film polarizer, the second Faraday rotator, the second half-wave plate, and the second polarizer in sequence, and then passes through the second regenerative amplifier for in-oscillation amplification, and is output after dispersion compensation by the second dispersion grating.

[0021] In one embodiment, the output after passing through the first regenerative amplifier for in-oscillation amplification and then through dispersion compensation by the first dispersion grating is as follows:

[0022] When no voltage is applied across the two ends of the first electro-optic crystal, one of the laser beams makes the first round trip through the first electro-optic crystal;

[0023] Then the laser beam is deflected by 90 degrees and enters the thin-film gain module by reflection through the first polarizer;

[0024] Before the laser beam reaches the first electro-optic crystal again, a quarter-wave voltage is applied across the two ends of the first electro-optic crystal. The laser beam makes another round trip through the first polarizer, and then the laser beam continuously oscillates and amplifies in the first regenerative amplifier until the energy reaches the maximum value. Then the voltage across the two ends of the first electro-optic crystal is removed. The laser beam sequentially passes through the first polarizer, the first half-wave plate, the first Faraday rotator, and the first thin-film polarizer, and then undergoes dispersion compensation through the first dispersion grating to finally obtain the required hundred-femtosecond laser.

[0025] In one embodiment, the output after passing through the second regenerative amplifier for in-oscillation amplification and then through dispersion compensation by the second dispersion grating is as follows:

[0026] When no voltage is applied across the two ends of the second electro-optic crystal, the other laser beam makes the first round trip through the second electro-optic crystal;

[0027] Then the laser beam is deflected by 90 degrees and enters the thin-film gain module by reflection through the second polarizer;

[0028] Before the laser beam reaches the second electro-optic crystal again, a quarter-wave voltage is applied across the two ends of the second electro-optic crystal. The laser beam makes another round trip through the second polarizer, and then the laser beam continuously oscillates and amplifies in the second regenerative amplifier until the energy reaches the maximum value. Then the voltage across the two ends of the second electro-optic crystal is removed. The laser beam sequentially passes through the second polarizer, the second half-wave plate, the second Faraday rotator, and the second thin-film polarizer, and then undergoes dispersion compensation through the second dispersion grating to finally obtain the required picosecond laser.

[0029] In the above-mentioned thin-disk dual-pulse-width output laser and its laser output method, a femtosecond laser is divided into two paths by a polarization beam splitter module. One path is for pulse broadening, and the other path keeps the pulse width unchanged. The two laser pulses after beam splitting are respectively injected into the corresponding regenerative amplifiers. The two regenerative amplifiers share a gain amplification module and are separated by the angles of incidence on the crystal. The amplified pulses are respectively dispersion-compensated for the pulses by the dispersion control modules, and finally a dual-pulse laser output of hundreds of femtoseconds and several picoseconds is output. Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of a thin-disk dual-pulse-width output laser of an embodiment.

[0031] In the figure, 1 - femtosecond laser, 2 - polarization beam splitter module, 3 - chirped volume Bragg grating, 4 - second mirror, 5 - first mirror, 6 - second thin-film polarizer, 7 - first thin-film polarizer, 8 - second Faraday rotator, 9 - second half-wave plate, 10 - first Faraday rotator, 11 - first half-wave plate, 12 - second polarizer, 13 - second quarter-wave plate, 14 - second electro-optic crystal, 15 - third end mirror, 16 - first polarizer, 17 - first quarter-wave plate, 18 - first electro-optic crystal, 19 - first end mirror, 20 - sixth mirror, 21 - third mirror, 22 - fourth mirror, 23 - thin-disk gain module, 24 - fifth mirror, 25 - fourth end mirror, 26 - second end mirror, 27 - second dispersion grating, 28 - first dispersion grating. Detailed Embodiments

[0032] Please refer to Figure 1 , an embodiment of a thin-disk dual-pulse-width output laser provided by the present invention includes: a femtosecond laser 1; a polarization beam splitter module 2 for dividing the laser pulse output by the femtosecond laser 1 into two laser beams. One of the laser beams is sequentially introduced into the first regenerative amplifier through the first mirror 5, the first thin-film polarizer 7, the first Faraday rotator 10, the first half-wave plate 11, and the first polarizer 16, oscillated and amplified, and then output after dispersion compensation by the first dispersion grating 28; the other laser beam is broadened by the chirped volume Bragg grating 3 and then sequentially introduced into the second regenerative amplifier through the second mirror 4, the second thin-film polarizer 6, the second Faraday rotator 8, the second half-wave plate 9, and the second polarizer 12, oscillated and amplified, and then output after dispersion compensation by the second dispersion grating 27.

[0033] In one embodiment, the repetition frequency of the femtosecond laser 1 is 10 - 100 MHz, the maximum average power is 5 - 50 mW, the pulse width is 100 - 800 fs, and the central wavelength is 1030 nm.

[0034] Specifically, in one embodiment, the first regenerative amplifier and the second regenerative amplifier can be Figure 1 the standing-wave regenerative amplifier shown, and in other embodiments, the first regenerative amplifier and the second regenerative amplifier can also be traveling-wave regenerative amplifiers or traveling-wave amplifiers.

[0035] Specifically, in one embodiment, each of the first regenerative amplifiers includes a first end mirror 19, a first electro-optic crystal 18, a first quarter-wave plate 17, a first polarizer 16, a third mirror 21, a fourth mirror 22, a thin disk gain module 23, a fifth mirror 24, and a second end mirror 26.

[0036] Specifically, in one embodiment, each of the second regenerative amplifiers includes a third end mirror 15, a second electro-optic crystal 14, a second quarter-wave plate 13, a second polarizer 12, a sixth mirror 20, and a fourth end mirror 25. The second regenerative amplifier shares the fourth mirror 22, the thin disk gain module 23, and the fifth mirror 24 with the first regenerative amplifier.

[0037] Specifically, in one embodiment, the thin disk gain module 23 can be a Yb:YAG thin disk crystal, a Yb:KGW thin disk crystal, a Yb:KYW thin disk crystal, a titanium sapphire thin disk crystal, or the like.

[0038] In one embodiment, the first dispersion grating 28 and the second dispersion grating 27 can be chirped volume Bragg gratings, CFBGs, reflective gold gratings, or transmissive dielectric film gratings.

[0039] A laser output method for a thin disk dual pulse width output laser as described above includes:

[0040] Outputting laser pulses from a femtosecond laser 1;

[0041] The polarization beam splitting module 2 splits the laser pulses into two laser beams;

[0042] One of the laser beams is sequentially introduced into the first regenerative amplifier through a first mirror 5, a first thin film polarizer 7, a first Faraday rotator 10, a first half-wave plate 11, and a first polarizer 16, oscillated and amplified therein, and then output after dispersion compensation by the first dispersion grating 28;

[0043] The other laser beam is broadened by a chirped volume Bragg grating 3 and then sequentially introduced into the second regenerative amplifier through a second mirror 4, a second thin film polarizer 6, a second Faraday rotator 8, a second half-wave plate 9, and a second polarizer 12, oscillated and amplified therein, and then output after dispersion compensation by the second dispersion grating 27.

[0044] Specifically, in one embodiment, the first dispersion grating 28 is used for dispersion compensation to finally obtain an output of hundred femtosecond pulses, such as about 350 fs.

[0045] In one embodiment, another laser beam is broadened by the chirped volume Bragg grating 3 and finally outputs a double-pulse laser with a few picoseconds, such as about 2.7 ps.

[0046] Specifically, in one of the embodiments, the specific process of the output after the internal oscillation amplification in the first regenerative amplifier and the dispersion compensation by the first dispersion grating 28 can be as follows:

[0047] When no voltage is applied across the first electro-optic crystal 18, one of the laser beams makes its first round trip through the first electro-optic crystal 18.

[0048] Then the laser beam is deflected by 90 degrees and enters the thin disk gain module 23 through reflection by the first polarizer 16.

[0049] Before the laser beam reaches the first electro-optic crystal 18 again, a quarter-wave voltage is applied across the first electro-optic crystal 18. The laser beam makes another round trip through the first polarizer 16 without change, and then the laser beam continues to oscillate and amplify in the first regenerative amplifier. When the energy reaches the maximum value, the voltage across the first electro-optic crystal 18 is removed. The laser beam sequentially passes through the first polarizer 16, the first half-wave plate 11, the first Faraday rotator 10, and the first thin-film polarizer 7, and then is dispersion-compensated by the first dispersion grating 28 to finally obtain the required laser output.

[0050] Specifically, in one of the embodiments, the specific process of the output after the internal oscillation amplification in the second regenerative amplifier and the dispersion compensation by the second dispersion grating can be as follows:

[0051] For the other path, when no voltage is applied across the second electro-optic crystal 14, the other laser beam makes its first round trip through the second electro-optic crystal 14.

[0052] Then the laser beam is deflected by 90 degrees and enters the thin disk gain module 23 through reflection by the second polarizer 12.

[0053] Before the laser beam reaches the second electro-optic crystal 14 again, a quarter-wave voltage is applied across the second electro-optic crystal 14. The laser beam makes another round trip through the second polarizer 12, and then the laser beam continues to oscillate and amplify in the second regenerative amplifier. When the energy reaches the maximum value, the voltage across the second electro-optic crystal 14 is removed. The laser beam sequentially passes through the second polarizer 12, the second half-wave plate 9, the second Faraday rotator 8, and the second thin-film polarizer 6, and then is dispersion-compensated by the second dispersion grating 27 to finally obtain the required laser output.

[0054] The specific structures and related definitions of the various components involved in the method are the same as those described in the above thin disk double-pulse output laser, and will not be elaborated here.

[0055] In the above-mentioned thin-sheet dual-pulse-width output laser and its laser output method, a femtosecond laser is divided into two paths through a polarization beam splitter module. One path is used for pulse broadening, and the other path keeps the pulse width unchanged. The two laser pulses after beam splitting are respectively injected into the corresponding regenerative amplifiers. The two regenerative amplifiers share a gain amplification module and are separated by the incident angle on the crystal. The amplified pulses are respectively dispersion-compensated for the pulses through the dispersion control module, and finally, dual-pulse lasers with a duration of hundreds of femtoseconds and several picoseconds are output. In specific applications, the above-mentioned thin-sheet dual-pulse-width output laser has a compact structure and can output two laser beams with the same wavelength but different pulse widths. Through dispersion control, it serves as the seed light source for the two regenerative amplifiers, and after amplification, two laser beams with durations of 2.7 ps and 350 fs are respectively obtained through dispersion compensation.

[0056] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A thin-film dual-pulse-width output laser, characterized in that Comprising: A femtosecond laser; A polarization beam splitting module for splitting the laser pulses output by the femtosecond laser into two laser beams; One of the laser beams sequentially passes through a first mirror, a first thin film polarizer, a first Faraday rotator, a first half-wave plate, and a first polarizer and is introduced into a first regenerative amplifier for oscillation amplification, and then is dispersion compensated by a first dispersion grating and outputs femtosecond laser; the other laser beam is broadened by a second chirped volume Bragg grating, and then sequentially passes through a second mirror, a second thin film polarizer, a second Faraday rotator, a second half-wave plate, and a second polarizer and is introduced into a second regenerative amplifier for oscillation amplification, and then is dispersion compensated by a second dispersion grating and outputs picosecond laser; The first regenerative amplifier includes a first end mirror, a first electro-optic crystal, a first quarter-wave plate, the first polarizer, a third mirror, a fourth mirror, a thin disk gain module, a fifth mirror, and a second end mirror; The second regenerative amplifier includes a third end mirror, a second electro-optic crystal, a second quarter-wave plate, the second polarizer, a sixth mirror, and a fourth end mirror. The second regenerative amplifier shares the fourth mirror, the thin disk gain module, and the fifth mirror with the first regenerative amplifier; The first regenerative amplifier and the second regenerative amplifier are standing-wave regenerative amplifiers, traveling-wave regenerative amplifiers, or traveling-wave amplifiers.

2. The thin-film dual pulse-width output laser according to claim 1, characterized in that, The thin disk gain module is a Yb:YAG thin disk crystal, a Yb:KGW thin disk crystal, a Yb:KYW thin disk crystal, or a titanium sapphire thin disk crystal.

3. The thin-film dual pulse-width output laser according to claim 1, wherein The first dispersion grating and the second dispersion grating are chirped volume Bragg gratings, CFBGs, reflective gold gratings, or transmissive dielectric film gratings.

4. The thin-film dual pulse-width output laser according to claim 1, wherein, The repetition rate of the femtosecond laser is 10 - 100 MHz, the maximum average power is 5 - 50 mW, the pulse width is 100 - 800 fs, and the central wavelength is 1030 nm.

5. A laser output method for a thin-film dual pulse-width output laser as described in any one of claims 1-4, characterized in that, Comprising: Outputting laser pulses from a femtosecond laser; A polarization beam splitting module splitting the laser pulses into two laser beams; One of the laser beams sequentially passes through a first mirror, a first thin film polarizer, a first Faraday rotator, a first half-wave plate, and a first polarizer, then passes through a first regenerative amplifier for oscillation amplification, and then is dispersion compensated by a first dispersion grating and outputs; The other laser beam is broadened by a second chirped volume Bragg grating, and then sequentially passes through a second mirror, a second thin film polarizer, a second Faraday rotator, a second half-wave plate, and a second polarizer, and then passes through a second regenerative amplifier for oscillation amplification, and then is dispersion compensated by a second dispersion grating and outputs.

6. The laser output method of the thin-film double pulse width output laser according to claim 5, characterized in that The output after passing through a first regenerative amplifier for oscillation amplification and then being dispersion compensated by a first dispersion grating is: When no voltage is applied across the first electro-optic crystal, one of the laser beams makes a first round trip through the first electro-optic crystal; Then the laser beam is deflected by 90 degrees and enters the thin disk gain module through reflection by the first polarizer; Before the laser beam reaches the first electro-optic crystal again, a quarter-wave voltage is applied across the first electro-optic crystal. The laser beam then makes another round trip through the first polarizer, and then the laser beam continuously oscillates and amplifies in the first regenerative amplifier until the energy reaches its maximum value. At this point, the voltage across the first electro-optic crystal is removed. The laser beam then passes through the first polarizer, the first half-wave plate, the first Faraday rotator, and the first thin-film polarizer in sequence, and then undergoes dispersion compensation through the first dispersion grating to finally obtain the required hundred-femtosecond laser.

7. The laser output method of the thin-film dual pulse width output laser according to claim 5, characterized in that The output after oscillating and amplifying in the second regenerative amplifier and then undergoing dispersion compensation through the second dispersion grating is as follows: Another laser beam makes its first round trip through the second electro-optic crystal without a voltage being applied across the second electro-optic crystal. Then the laser beam is deflected by 90 degrees and enters the thin-film gain module by reflection through the second polarizer. Before the laser beam reaches the second electro-optic crystal again, a quarter-wave voltage is applied across the second electro-optic crystal. The laser beam then makes another round trip through the second polarizer, and then the laser beam continuously oscillates and amplifies in the second regenerative amplifier until the energy reaches its maximum value. At this point, the voltage across the second electro-optic crystal is removed. The laser beam then passes through the second polarizer, the second half-wave plate, the second Faraday rotator, and the second thin-film polarizer in sequence, and then undergoes dispersion compensation through the second dispersion grating to finally obtain the required picosecond laser.

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