CN111834874B - Pulsed lasers and laser systems - Google Patents
Pulsed lasers and laser systems Download PDFInfo
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- CN111834874B CN111834874B CN202010737050.3A CN202010737050A CN111834874B CN 111834874 B CN111834874 B CN 111834874B CN 202010737050 A CN202010737050 A CN 202010737050A CN 111834874 B CN111834874 B CN 111834874B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/102—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
- H01S3/1022—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the optical pumping
- H01S3/1024—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the optical pumping for pulse generation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/102—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
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Abstract
本发明公开了一种脉冲激光器及激光系统，其中，脉冲激光器，包括：脉冲光源，用于产生初始激光脉冲；展宽器，与所述脉冲光源进行耦合连接，用于对所述初始激光脉冲进行脉冲展宽以生成第一激光脉冲；脉冲选择器，与所述展宽器耦合连接，用于对所述第一激光脉冲进行选择并获取第二激光脉冲；冷冻真空放大器，与所述脉冲选择器耦合连接，用于所述第二激光脉冲进行放大；脉冲压缩器，与所述冷冻真空放大器耦合连接，用于对所述第二激光脉冲进行压缩并生成目的激光脉冲。本发明实施例中的脉冲激光器可提供高重复频率、超强功率的超短脉冲。
The present invention discloses a pulse laser and a laser system, wherein the pulse laser comprises: a pulse light source for generating an initial laser pulse; a stretcher coupled to the pulse light source for stretching the initial laser pulse to generate a first laser pulse; a pulse selector coupled to the stretcher for selecting the first laser pulse and obtaining a second laser pulse; a cryo-vacuum amplifier coupled to the pulse selector for amplifying the second laser pulse; and a pulse compressor coupled to the cryo-vacuum amplifier for compressing the second laser pulse and generating a target laser pulse. The pulse laser in the embodiment of the present invention can provide ultra-short pulses with high repetition frequency and ultra-high power.
Description
Technical Field
The invention relates to the technical field of laser pulses, in particular to a pulse laser and a laser system.
Background
With the continuous development of laser technology, the peak power of the ultra-short laser system can reach the level of clapping watt (10 15 W), and the ultra-short laser system is widely applied to experiments of interaction of ultra-strong laser substances, such as ultra-short X-ray radiation, generation of higher harmonics, acceleration of laser tail wave field particles, rapid ignition laser nuclear fusion and the like.
In the related art, the ultra-short laser system generally uses Ti: sapphire crystal as the laser crystal, however, the upper level lifetime of Ti: sapphire crystal is short, resulting in lower electro-optical efficiency.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a pulse laser which can provide ultra-short pulses with high repetition frequency and ultra-strong power.
The invention also provides a laser system with the pulse laser.
The pulse laser comprises a pulse light source, a stretcher, a pulse selector, a regenerative amplifier, a frozen vacuum amplifier and a pulse compressor, wherein the pulse light source is used for generating initial laser pulses, the stretcher is coupled with the pulse light source and used for stretching the initial laser pulses to generate first laser pulses, the pulse selector is coupled with the stretcher and used for selecting the first laser pulses and acquiring second laser pulses, the regenerative amplifier is coupled with the pulse selector and used for amplifying the second laser pulses, the frozen vacuum amplifier is coupled with the pulse selector and used for amplifying the second laser pulses, and the pulse compressor is coupled with the frozen vacuum amplifier and used for compressing the second laser pulses and generating target laser pulses.
The pulse laser has at least the following beneficial effects that the pulse light source is used for providing initial laser pulses, and the stretcher spreads the initial laser pulses according to the wavelength of the initial laser pulses and forms a pulse sequence. The pulse selector selects laser pulses to be amplified in the pulse sequence according to preset parameters, and after the laser pulses to be amplified are amplified by a preset value through the regenerative amplifier, the laser pulses to be amplified are transmitted to the frozen vacuum amplifier, and the laser pulses to be amplified are amplified secondarily. After the amplification treatment of the laser pulse to be amplified is completed, the laser pulse to be compressed is generated, and the pulse compressor compresses the laser pulse to be compressed and generates the target laser pulse.
According to some embodiments of the invention, the pulse selector comprises a pulse selection controller, a pulse detection unit and a pulse detection unit, wherein the pulse selection controller is connected with the pulse selector and is used for controlling the pulse selector;
According to some embodiments of the invention, the frozen vacuum amplifier comprises a first laser window plate, a third laser crystal, a low-temperature controller, a third pumping device and a second laser window plate, wherein the third laser crystal is coupled with the first laser window plate, the low-temperature controller is connected with the third laser crystal and used for controlling the temperature of the third laser crystal, the third pumping device is coupled with the third laser crystal and used for exciting the third laser crystal, the second laser window plate is coupled with the third laser crystal, and the first laser window plate and the second laser window plate are arranged opposite to each other to define an amplifying cavity.
According to some embodiments of the invention, the third laser crystal is a Yb: KGW crystal.
According to some embodiments of the invention, the pulse selector comprises a first polaroid for receiving the first laser pulse, a first half-wave plate coupled with the first polaroid for carrying out phase adjustment on the first laser pulse and forming a first polarized pulse, a polarization state rotator coupled with the first half-wave plate for carrying out polarization treatment on the polarization state of the first polarized pulse and generating the second laser pulse, and a second polaroid coupled with the polarization state rotator for carrying out adjustment on the polarization state and/or propagation direction of the second laser pulse.
According to some embodiments of the invention, the pulse selector further comprises a first quarter wave plate for performing phase adjustment on the second laser pulse, a pockels cell coupled to the first quarter wave plate for performing phase adjustment on the second laser pulse, and a first high reflection mirror coupled to the pockels cell for reflecting the second laser pulse.
According to some embodiments of the invention, the regenerative amplifier further comprises a first pumping device for performing a first amplification process on the second laser pulse, and a second pumping device coupled to the first pumping device for performing a second amplification process on the second laser pulse.
According to some embodiments of the invention, the first pumping device comprises a first laser crystal, a first dichroic mirror, a first convex lens group, a first pumping optical fiber, a first semiconductor pumping source, a second semiconductor pumping source and a second pumping optical fiber, wherein the first dichroic mirror is coupled with the first laser crystal, the first convex lens group is coupled with the first dichroic mirror and arranged on one side of the first dichroic mirror away from the first laser crystal, the first pumping optical fiber is coupled with the first convex lens group, the first semiconductor pumping source is coupled with the first pumping optical fiber and used for exciting the first laser crystal, the second pumping device comprises a second laser crystal, the second dichroic mirror is coupled with the second laser crystal, the second convex lens group is coupled with the second dichroic mirror and arranged on the two sides of the second dichroic mirror away from the second laser crystal, the second pumping optical fiber is coupled with the second convex lens group, and the second semiconductor pumping source is coupled with the second pumping optical fiber and used for exciting the second laser crystal.
According to some embodiments of the invention, the pulse compressor comprises a first pulse compressor coupled to the freeze vacuum amplifier for compressing the second laser pulse and generating a first target pulse, and a second pulse compressor coupled to the first pulse compressor for non-linearly compressing the first target pulse and generating a second target pulse.
A laser system according to an embodiment of the second aspect of the invention comprises a pulsed laser according to any of the embodiments described above.
The laser system provided by the embodiment of the invention has at least the following beneficial effects that the pulse laser is used for providing the ultra-short pulse with high repetition frequency and ultra-high power for the laser system.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic diagram of a pulse laser according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a pulse selector and a regenerative amplifier according to an embodiment of the invention;
fig. 3 is a schematic diagram of a freeze vacuum amplifier according to an embodiment of the present invention.
Reference numerals:
100. Pulse light source 200, isolator 300, stretcher, 410, pulse selection controller 420, pulse selector 500, regenerative amplifier 700, freeze vacuum amplifier 800, pulse compressor 801, first pulse compressor 802, second pulse compressor 421, first polarizer 422, first half-wave plate 423, polarization rotator 424, second polarizer 425, first quarter-wave plate 426, pockels, 427, first high reflection mirror, 501, first semiconductor pump source 502, first pump fiber 503, first convex lens group 504, first dichroic mirror, 505, first laser crystal 506, second semiconductor pump source 507, second pump fiber 508, second convex lens group 508, 509, second dichroic mirror group 510, second laser crystal 511, fourth high reflection mirror 512, second high reflection mirror 513, third high reflection mirror 514, fourth high reflection mirror 600, pump source 701, first window, third window, second window, 703, third window, second mirror 706, third window, second mirror 708, second mirror, 706, third cavity, transmission device, first cavity, optical cavity, and transmission device.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, a number means one or more, a number means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.
Referring to fig. 1, the pulse laser includes a pulse light source 100 for generating an initial laser pulse, a stretcher 300 coupled to the pulse light source 100 for stretching the initial laser pulse to generate a first laser pulse, a pulse selector 420 coupled to the stretcher 300 for selecting the first laser pulse and acquiring a second laser pulse, a regenerative amplifier 500 coupled to the pulse selector 420 for amplifying the second laser pulse, a freeze vacuum amplifier 700 coupled to the pulse selector 420 for amplifying the second laser pulse, and a pulse compressor 800 coupled to the freeze vacuum amplifier 700 for compressing the second laser pulse and generating a target laser pulse.
The initial laser pulse is supplied by the pulse light source 100, and the stretcher 300 spreads the initial laser pulse according to the wavelength of the initial laser pulse and forms a first laser pulse (pulse train). The pulse selector 420 selects laser pulses to be amplified in the pulse sequence according to preset parameters, and transmits the laser pulses to be amplified to the freeze vacuum amplifier 700 to amplify the laser pulses to be amplified. After the amplification process of the laser pulse to be amplified is completed, a laser pulse to be compressed is generated, and the pulse compressor 800 compresses the laser pulse to be compressed and generates a target laser pulse. The pulse compressor 800 reconverges the amplified second laser pulse according to the spectrum, and recovers the pulse width, thereby forming a femtosecond laser pulse with high instantaneous power.
The pulse selector selects laser pulses to be amplified in the pulse sequence according to preset parameters, and after the laser pulses to be amplified are amplified by a preset value through the regenerative amplifier, the laser pulses to be amplified are transmitted to the frozen vacuum amplifier, and the laser pulses to be amplified are amplified secondarily.
In some embodiments, the pulsed light source 100 may be a femtosecond pulsed light source 100 for providing femtosecond pulses. For example, the pulsed light source 100 is a mode-locked fiber femtosecond laser, which can output femtosecond laser pulses with a pulse power of about 1nJ, a pulse width of about 200fs, and a repetition rate of 40MHz.
The initial laser pulse of the femto-second order is supplied by the femto-second pulse light source 100, and pulse selection is performed on the initial laser pulse to perform amplification processing and compression processing on the target pulse to obtain the target laser pulse. The target laser pulse is an ultrashort pulse with high repetition frequency and super power.
In addition, the pump source 600 is used to provide energy to the laser crystals in the regenerative amplifier 500 and the freeze vacuum amplifier 700 to achieve population inversion.
In some embodiments, by setting the initial laser pulse and the device parameters, a high repetition rate ultrashort pulse with a pulse energy up to 25mJ, a pulse width less than 25fs, a peak power up to 1TW (1012W), and a repetition rate up to 1kHz can be provided.
In some embodiments, a laser isolator 200 is disposed between the pulse light source 100 and the stretcher 300, and a unidirectional pulse channel is constructed by the laser isolator 200, where the unidirectional pulse channel allows the initial laser pulse generated by the pulse light source 100 to be transmitted to the stretcher 300, and the super-high ultra-short pulse with high repetition frequency generated in the pulse laser cannot pass through the laser isolator 200, so that the pulse light source 100 is isolated and protected. The laser isolator 200 includes an isolation half-wave plate, an isolation polarizing plate disposed opposite to the isolation half-wave plate, and a Faraday rotator disposed between the isolation half-wave plate and the isolation polarizing plate. The isolation half wave plate is arranged opposite to the isolation polaroid, and the included angle is not 0. The protection of the pulse light source 100 is achieved by isolating the amplified laser pulses from reentering the pulse light source 100 while the initial laser pulses are made to enter the stretcher 300 by the laser isolator 200.
In some embodiments, stretcher 300 is a Martin stretcher 300, with a transmissive grating disposed within Martin stretcher 300 having a scribe line density of 1600 lines/mm. The pulse width of the initial laser pulse provided by the pulse light source 100 is stretched from about 200fs to about 0.5ns, i.e., the initial laser pulse is stretched from the femtosecond scale to the subnanosecond scale.
Further, the Martin stretcher 300 may be a standard non-dispersive Martin stretcher 300.
In some embodiments, the pulsed laser further comprises a pulse selection controller 410 coupled to the pulse selector 420 for controlling the pulse selector 420.
The pulse selector 420 sequentially selects a pulse sequence formed by the initial laser pulse stretching according to a preset switching frequency of the pulse selection controller 410, and only one sub-nanometer pulse is selected at a time. The second nanometer-level pulse may be the second laser pulse.
The regenerative amplifier 500 amplifies the second laser pulse of the sub-nanometer level. For example, the second laser pulse is transmitted back and forth between the pulse selector 420 and the regenerative amplifier 500 a plurality of times, the second laser pulse is increased in energy by the working medium and the pump source in the regenerative amplifier 500, and the pulse energy may be increased to 2mJ or more.
When the pulse energy of the second laser pulse is increased to a preset value, the second laser pulse is transmitted to the freeze vacuum amplifier 700 and amplified to form a laser pulse to be compressed. The pulse energy of the second laser pulse is amplified to 40mJ by the freeze vacuum amplifier 700. Wherein the portion of the first laser pulse not selected by the pulse selector 420 will be reflected outside the pulsed laser and not enter the freeze vacuum amplifier 700.
Compressing the amplified second laser pulse to compress the second laser pulse width to within a preset width.
In some embodiments, the cryovacuum amplifier 700 comprises a first laser window 701, a third laser crystal 702 coupled to the first laser window 701, a cryogenic controller 704 coupled to the third laser crystal 702 for controlling the temperature of the third laser crystal 702, a third pumping device 710 coupled to the third laser crystal 702 for exciting the third laser crystal 702, a second laser window 703 coupled to the third laser crystal 702, wherein the first laser window 701 is disposed opposite the second laser window 703 to define an amplifying cavity.
A vacuum chamber is constructed by the first laser window 701, the second laser window 703 to form an enlarged cavity. The temperature of the third laser crystal 702 is controlled by the low temperature controller 704 to switch the energy level of the third laser crystal 702, thereby adjusting the thermal conductivity of the third laser crystal 702.
In some embodiments, third laser crystal 702 is a Yb: KGW crystal. The vacuum chamber constructed by the first laser window 701 and the second laser window 703 can reach at least 10-2Pa level, and the low-temperature controller 704 adjusts the temperature of the third laser crystal 702 to 77K-200K, so that the Yb/KGW crystal is converted from a three-energy level structure to a four-energy level structure at normal temperature.
Referring to fig. 1 and 2, in some embodiments, the pulse selector 420 includes a first polarizer 421 for receiving a first laser pulse, a first half-wave plate 422 coupled to the first polarizer 421 for performing phase adjustment on the first laser pulse and forming a first polarized pulse, a polarization rotator 423 coupled to the first half-wave plate 422 for performing polarization processing on a polarization state of the first polarized pulse and generating a second laser pulse, and a second polarizer 424 coupled to the polarization rotator 423 for adjusting a polarization state and/or a propagation direction of the second laser pulse. The first polarizer 421 is coupled to the stretcher 300 to receive the first laser pulses obtained by pulse stretching via the stretcher 300.
The first laser pulse and the first polarizer 421 have the same polarization angle, the first laser pulse is adjusted by the first half-wave plate 422 and the polarization rotator 423, and the second laser pulse and the first laser pulse have different polarization angles. For example, the first laser pulse is matched with the polarization angle of the first polarizer 421, the first laser pulse is transmitted to the first half wave plate 422 through the first polarizer 421, the second laser pulse is not matched with the polarization angle of the first polarizer 421, and the second laser pulse is reflected to the fourth high reflection mirror 511 through the first polarizer 421.
The pulse sequence of the first laser pulse is selected by the pulse selection controller 410, the pulse selector 420 to obtain the second laser pulse. The first laser pulse enters the pulse selector 420, the first laser pulse is consistent with the polarization direction of the first polarizer 421, the first half-wave plate 422 adjusts the phase of the first laser pulse and forms a first polarized pulse, and the polarization state rotator 423 polarizes the polarization state of the first polarized pulse and generates a second laser pulse.
The polarization state and/or propagation direction of the second laser pulse is adjusted by the second polarizer 424 so that the second laser pulse enters the regenerative amplifier 500. Wherein the polarization state rotator 423 may be a faraday rotator.
In some embodiments, the pulse selector 420 further comprises a first quarter wave plate 425 coupled to the second polarizer 424 for phase adjusting the second laser pulse, a pockels cell 426 coupled to the first quarter wave plate 425 for phase adjusting the second laser pulse, and a first high reflection mirror 427 coupled to the pockels cell 426 for reflecting the second laser pulse.
The second laser pulse passes through the first quarter wave plate 425, the pockels cell 426, the first high reflecting mirror 427 and reflects on the surface of the first high reflecting mirror 427 in sequence, and the second laser pulse passes through the pockels cell 426, the first quarter wave plate 425 again and reflects via the second polarizing plate 424 and is transmitted into the regenerative amplifier 500.
In some embodiments, the pulse voltage is generated by the pulse selection controller 410 to control the operating state of the prack ear box 426, for example, the pulse selection controller 410 generates about 4KV high voltage pulses to control the polarization state of the prack ear box 426 such that the optical properties of the prack ear box 426 are equivalent to a quarter wave plate.
When the pulse selection controller 410 has no voltage output, the second laser pulse enters the pulse selector 420 and then is reflected by the second high-reflection mirror 512 and the third high-reflection mirror 513 to enter the regenerative amplifier 500. The second laser pulse is amplified by the regenerative amplifier 500 and then enters the pulse selector 420 again. At this time, the pulse selection controller 410 outputs a high voltage pulse such that the second laser pulse is again introduced into the regenerative amplifier 500, and the laser pulse subsequently introduced is reflected or absorbed by the pulse selector 420. Since the subsequently incoming laser pulse is absorbed or reflected, the regenerative amplifier 500 amplifies only the second laser pulse.
The third high-reflection mirror 513 and the fourth high-reflection mirror 514 can construct a resonant cavity to make the second laser pulse stably transmitted in the intermediate regenerative amplifier 500.
In some embodiments, the second high mirror 512 is the same multiplexed mirror as the first cavity mirror 711 to adjust the transmission path of the laser pulses.
The second laser pulse enters the regenerative amplifier 500 and is amplified twice, so that the energy of the second laser pulse is increased to a preset power.
In some embodiments, the regenerative amplifier 500 further comprises a first pumping device for performing a first amplification process on the second laser pulse, and a second pumping device coupled to the first pumping device for performing a second amplification process on the second laser pulse.
The second laser pulse enters the pulse of the regenerative amplifier 500 and is coupled out to the corresponding laser crystal by the optical fiber to perform pulse amplification. The first pumping device and the second pumping device are symmetrically arranged.
In some embodiments, the first pumping device comprises a first laser crystal 505, a first dichroic mirror 504 coupled to the first laser crystal 505, a first convex lens group 503 coupled to the first dichroic mirror 504 and disposed on a side of the first dichroic mirror 504 away from the first laser crystal 505, a first pumping optical fiber 502 coupled to the first convex lens group 503, and a first semiconductor pumping source 501 coupled to the first pumping optical fiber 502 for exciting the first laser crystal 505. The second pumping device comprises a second laser crystal 510, a second dichroic mirror 509 coupled with the second laser crystal 510, a second convex lens group 508 coupled with the second dichroic mirror 509 and arranged on two sides of the second dichroic mirror 509 far away from the second laser crystal 510, a second pumping optical fiber 507 coupled with the second convex lens group 508, and a second semiconductor pumping source 506 coupled with the second pumping optical fiber 507 for exciting the second laser crystal 510.
The first laser crystal 505 and the second laser crystal 510 are tangent to each other in Ng direction, and axes of the first laser crystal 505, the second laser crystal 510 and the second laser pulse in parallel to each other in polarization direction are Nm and Np, respectively.
The first laser crystal 505 and the second laser crystal 510 are pumped by corresponding pumping sources, so that the particle numbers in the laser crystals are reversed.
When the second laser pulse is amplified to the preset power, the pulse selection controller 410 stops outputting the high voltage pulse signal so that the amplified second laser pulse is transmitted to the freeze vacuum amplifier 700 via the pulse selector 420. The output pulse energy of the amplified second laser pulse in this embodiment is about 2mJ, and the pulse selection controller 410 outputs a square wave high voltage signal of about 4KV with a frequency of 1000Hz.
In some embodiments, the first laser crystal 505 and the second laser crystal 510 are Yb/KGW crystals, and the first pumping device and the second pumping device are symmetrically arranged to construct the dual-crystal regenerative amplifier 500, so as to secondarily amplify the laser pulse. Particles in the activated Yb: KGW crystal are pumped from the ground state to a high energy level by using a semiconductor pump source to excite the Yb: KGW crystal to achieve population inversion. For example, the semiconductor pump source is a multimode fiber coupled semiconductor laser, the transmission fiber is a multimode fiber, the working mode is Continuous (CW) or quasi-continuous (QCW), and the output wavelength is 806 nm-985 nm.
In some embodiments, pulse compressor 800 includes a first pulse compressor 801 coupled to freeze vacuum amplifier 700 for compressing the second laser pulse and generating a first target pulse, and a second pulse compressor 802 coupled to first pulse compressor 801 for non-linearly compressing the first target pulse and generating a second target pulse.
The first pulse compressor 801 is Treacy pulse compressors, the first pulse compressor 801 can compress the laser pulse to be compressed amplified by the freeze vacuum amplifier 700 to generate a first target pulse of about 28mJ, and the second pulse compressor 802 can compress the first target pulse in a nonlinear manner to obtain a second target pulse. The first target pulse is a femtosecond pulse with the pulse width smaller than 300fs, and the second target pulse is a femtosecond pulse with the pulse width smaller than 25 fs.
In some embodiments, treacy pulse compressor is a standard Treacy pulse compressor for compressing the pulse width of the second laser pulse to the limit width and obtaining the first target pulse. For example, a standard Treacy pulse compressor is provided with a transmissive grating that can compress the pulse width of a sub-nanosecond high-energy laser pulse to about 280fs. The second laser pulse is a chirped pulse.
In some embodiments, the second pulse compressor 802 is a nonlinear pulse compressor 800, the nonlinear pulse compressor 800 compressing the second laser pulse (femtosecond pulse) that has reached the compression limit to a second target pulse (ultrashort pulse) through a nonlinear crystal, for example, non-linearly compressing the second laser pulse or the first target pulse through a Herriott-type multi-vent chamber. Specifically, the first target pulse of hundred femtoseconds is transmitted to the Herriott type multi-pass chamber filled with inert gas, and spectrum expansion is performed by using a nonlinear effect (self-phase modulation effect) to perform dispersion compensation compression on the first target pulse, so that the pulse width of the first target pulse is compressed to be less than or equal to one tenth of the initial pulse width.
The above embodiments are combined to provide an adaptive description of a specific embodiment.
Referring to fig. 1,2 and 3, the pulsed light source 100 generates an initial laser pulse of the femtosecond order, and the laser isolator 200 is used as a unidirectional pulse transmission channel, and the initial laser pulse can be transmitted to the stretcher 300 through the laser isolator 200. The stretcher 300 pulse stretches the first laser pulse of the femtosecond order by the second nanosecond order. The laser isolator 200 prevents the ultra-short pulse with high repetition frequency from being applied to the inside of the pulse light source 100 to isolate and protect the pulse light source 100.
The first laser pulse is transmitted to the pulse selector 420, and the pulse selector 420 selects a pulse sequence of the first laser pulse according to a control signal of the pulse selection controller 410 to obtain a second laser pulse according to a preset parameter.
For example, the pulse selection controller 410 includes a first polarizer 421, a first half-wave plate 422, a polarization rotator 423, a second polarizer 424, a first quarter-wave plate 425, a pockels cell 426, and a first high-reflection mirror 427, which are coupled in this order. Wherein the polarization state rotator 423 may be a faraday rotator.
The second laser pulse has the same polarization angle as the first polarizer 421, and the second laser pulse passes through the first half-wave plate 422 to adjust the phase and the polarization state rotator 423 to adjust the polarization angle, thereby obtaining the second laser pulse. The second laser pulse is aligned with the polarization angle of the second polarizer 424. When the second laser pulse passes through the first quarter wave plate 425, the pockels cell 426 and the first high reflection mirror 427 for the first time, the pulse selection controller 410 outputs no control signal, and the second laser pulse passes through the regenerative amplifier 500 for the first time for pulse amplification and is transmitted to the pulse selector 420 again.
When the second laser pulse passes through the first quarter wave plate 425, the pockels cell 426 and the first high reflection mirror 427 again, the pulse selection controller 410 outputs a high voltage signal, the transient state of the pockels cell 426 corresponds to the quarter wave plate, and the second laser pulse is turned back again into the regenerative amplifier 500 and amplified for the second pulse. And when the pulse selection controller 410 outputs a high voltage signal, the laser pulse subsequently entering the pulse selector 420 is reflected or absorbed, and cannot enter the regenerative amplifier 500 for amplification.
Wherein the second laser pulse is amplified to a preset power, the pulse selection controller 410 stops outputting the high voltage signal, and the second laser pulse amplified to the preset power is transmitted to the freeze vacuum amplifier 700 through the pulse selector 420. The three-level structure of Yb/KGW crystal (third laser crystal 702) is converted into a four-level structure from the normal temperature by the low temperature and vacuum conditions.
The working temperature of the freezing vacuum amplifier 700 is 77K-200K, and the working pressure is 10-2 Pa.
The frozen vacuum amplifier 700 comprises a first laser window 701, a third laser crystal 702 and a second laser window 703 which are sequentially arranged, wherein a low-temperature controller 704 is connected with the third laser crystal 702 to control the temperature of the third laser crystal 702, and a third pumping device 710 is coupled with the third laser crystal 702 to excite the third laser crystal 702.
The amplifying cavity is constructed by the first cavity mirror 711 and the second cavity mirror 707, and the Yb: KGW crystal which is in a vacuum low-temperature state and has four energy levels is used as a gain medium. The first cavity mirror 711 may be coupled to the pulse selector 420, and a third quarter wave plate 706 and a third dichroic mirror 705 are sequentially disposed between the second cavity mirror 707 and the frozen vacuum amplifier 700.
The first cavity mirror 711, the second polarizer 424, the frozen vacuum amplifier 700, the third dichroic mirror 705, the third quarter wave plate 706, and the second cavity mirror 707 are sequentially arranged to construct a complete amplifying cavity. The third pumping means 710 is coupled to the third laser crystal 702 in the cryopump volume 700 by a third dichroic mirror 705, thereby achieving population inversion of the third laser crystal 702.
Wherein a convex lens group 708 may be provided between the third pumping means 710 and the third dichroic mirror 705 to optimize the pumping performance. The operating power of the third pumping means 710 is about 200W. The second laser pulse is subjected to four times of amplification treatment by Yb: KGW crystal to increase the pulse energy to 40mJ.
In some embodiments, a laser system includes a pulsed laser in any of the embodiments described above. By using the pulse laser, ultra-short pulses with high repetition rate and ultra-high power are provided to the laser system. The laser system can provide an experiment environment with ultra-strong electromagnetic field, ultra-high energy density and ultra-strong light pressure for experimental research.
The above described apparatus embodiments are merely illustrative, wherein the units illustrated as separate components may or may not be physically separate, i.e. may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.
Claims (7)
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| CN1916746A (en) * | 2006-09-04 | 2007-02-21 | 中国科学院上海光学精密机械研究所 | Device and method for generating high repetition frequency ultrashort ultrastrong laser pulse train |
| CN102201644A (en) * | 2011-04-07 | 2011-09-28 | 中国科学院上海光学精密机械研究所 | Low-temperature Yb: YAG regenerative amplifier |
| CN212485789U (en) * | 2020-07-28 | 2021-02-05 | 深圳技术大学 | Pulsed Lasers and Laser Systems |
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| ES2664470T3 (en) * | 2009-11-26 | 2018-04-19 | Spherea Gmbh | Miniaturized arrangement of laser amplifier with pump source |
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| CN1916746A (en) * | 2006-09-04 | 2007-02-21 | 中国科学院上海光学精密机械研究所 | Device and method for generating high repetition frequency ultrashort ultrastrong laser pulse train |
| CN102201644A (en) * | 2011-04-07 | 2011-09-28 | 中国科学院上海光学精密机械研究所 | Low-temperature Yb: YAG regenerative amplifier |
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