CN114039269B - Method and system for suppressing amplified spontaneous emission in high-gain pulse laser amplifier - Google Patents
Method and system for suppressing amplified spontaneous emission in high-gain pulse laser amplifier Download PDFInfo
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- CN114039269B CN114039269B CN202111222053.4A CN202111222053A CN114039269B CN 114039269 B CN114039269 B CN 114039269B CN 202111222053 A CN202111222053 A CN 202111222053A CN 114039269 B CN114039269 B CN 114039269B
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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
- H01S3/10061—Polarization control
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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
- H01S3/10007—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers
- H01S3/10015—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by monitoring or controlling, e.g. attenuating, the input signal
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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
- H01S3/10007—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers
- H01S3/10023—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by functional association of additional optical elements, e.g. filters, gratings, reflectors
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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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Abstract
The invention provides a method and a system for inhibiting amplified spontaneous emission in a high-gain pulse laser amplifier, wherein the method comprises the following steps: obtaining a to-be-divided linear polarization short or ultra-short laser pulse sequence of seed laser output, screening the laser pulse sequence out of the sub-pulse sequence through an electro-optic polarization rotator, and rotating the polarization direction by 90 degrees; the first polarization beam splitter is used for carrying out polarization frequency division to obtain s polarized light reflected once and p polarized light transmitted once, and the second polarization beam splitter is used for reflecting the s polarized light twice; and injecting the s-polarized light after secondary reflection and the p-polarized light after transmission into the high-gain pulse laser amplifier in p-polarization mode from two opposite advancing directions through arranging advancing routes comprising a half-wave plate, a Faraday rotator combination and a plurality of plane reflectors respectively, so that the gain level in the laser amplifier after frequency division is kept unchanged. The invention realizes the effective suppression of amplified spontaneous emission in the high-gain pulse laser amplifier with frequency division requirement.
Description
Technical Field
The invention relates to the technical field of solid laser, in particular to a method and a system for inhibiting amplified spontaneous emission in a high-gain pulse laser amplifier.
Background
Currently, industrial picosecond lasers typically amplify seed laser light, having a pulse energy of only tens of nJ, to hundreds of μJ through a high gain traveling wave laser amplifier (10000 times). Such a high gain pulsed laser amplifier is very prone to generating Amplified Spontaneous Emission (ASE) light in the laser travel direction, which affects the pulse signal-to-noise ratio and beam quality of the output laser. Such ASE light can be suppressed by injecting seed laser light of sufficient power into the laser amplifier in combination with interstage filtering. When a picosecond laser is used for precision machining, the laser is required to have a frequency division function, i.e., to reduce the repetition frequency of the output laser while maintaining the pulse energy and beam quality unchanged. The current conventional approach to achieving the frequency division function is to use the 1 st order diffracted light of an acousto-optic switch (AOM) as the final output laser, which results in a power loss of about 15% of the laser beam as it passes through the AOM. If the frequency reduction is directly carried out at the seed end, the power of the seed injected into the laser amplifier is reduced, so that the original ASE inhibition mechanism is disabled.
Disclosure of Invention
The embodiment of the invention provides a method and a system for inhibiting amplified spontaneous emission in a high-gain pulse laser amplifier, which are used for solving the problems of large power loss or inhibition failure caused by power drop when the amplified spontaneous emission is inhibited in the conventional high-gain pulse amplifier.
In a first aspect, an embodiment of the present invention provides a method for suppressing amplified spontaneous emission in a high-gain pulse laser amplifier, including:
Obtaining a linear polarization short or ultra-short laser pulse output by seed laser, and rotating the polarization direction of the laser pulse screened by the linear polarization short or ultra-short laser pulse output by the seed laser by 90 degrees through an electro-optic polarization rotator;
Performing polarization frequency division on the laser pulse with the polarization direction rotated by 90 degrees through a first polarization beam splitter to obtain primarily reflected s-polarized light and transmitted p-polarized light, and secondarily reflecting the s-polarized light through a second polarization beam splitter;
And respectively arranging a traveling route comprising a half wave plate, a Faraday rotator combination and a plurality of plane reflectors, and injecting the secondary reflected s-polarized light and the transmitted p-polarized light into the high-gain pulse laser amplifier from two opposite traveling directions, so that the secondary reflected s-polarized light is converted into output laser and the transmitted p-polarized light is absorbed into a frequency division laser absorption tank.
Preferably, the left side of the first polarization beam splitter is inclined to form 45 degrees with the horizontal plane, the right side of the second polarization beam splitter is inclined to form 45 degrees with the horizontal plane, and the first polarization beam splitter and the second polarization beam splitter are arranged on the same vertical line.
Preferably, the half-wave plate comprises a first half-wave plate and a second half-wave plate; the Faraday rotator comprises a first Faraday rotator and a second Faraday rotator;
The s polarized light after secondary reflection and the transmitted p polarized light are respectively injected into the high gain pulse laser amplifier from two opposite advancing directions through arranging advancing routes comprising a half wave plate, a Faraday rotator combination and a plurality of plane reflectors, so that the s polarized light after secondary reflection is converted into output laser and the transmitted p polarized light is absorbed into a frequency division laser absorption pool, and the method comprises the following steps:
Before the secondary reflected s-polarized light is injected into the high-gain pulse laser amplifier, the s-polarized light enters from the first half wave plate and exits from the first Faraday rotator so that the polarization direction is rotated by 45 degrees to become p-polarized light, and the p-polarized light enters one side of the high-gain pulse laser amplifier after being reflected by a plane reflector; after passing through the high-gain pulse laser amplifier, the laser beam enters from the second half-wave plate and exits from the second Faraday rotator so that the polarization direction is rotated by 45 degrees to be changed into s-polarized light, and after passing through a plane reflector, the laser beam is reflected and output through the first polarization beam splitter.
Preferably, the step of injecting the s-polarized light after secondary reflection and the p-polarized light after transmission into the high-gain pulse laser amplifier from two opposite traveling directions through a traveling route including a half-wave plate, a faraday rotator combination and a plurality of plane mirrors, respectively, so that the s-polarized light after secondary reflection is converted into output laser light and the p-polarized light after transmission is absorbed into a frequency division laser absorption tank, and further comprises the steps of:
Before the transmitted p-polarized light is injected into the high-gain pulse laser amplifier, the p-polarized light enters the other side of the high-gain pulse laser amplifier after passing through a plurality of plane reflectors, enters from the second Faraday rotator and exits from the second half-wave plate, and the polarization direction rotation angle is unchanged; after the high-gain pulse laser amplifier, the high-gain pulse laser amplifier is reflected by a plane mirror, then enters the first Faraday rotator and exits from the first half-wave plate, so that the rotation angle of the polarization direction is unchanged and still becomes p-polarized light, and the p-polarized light is transmitted to the plane mirror through the second polarization beam splitter and then reflected to the frequency division laser absorption pool.
Preferably, the high gain pulsed laser amplifier comprises a gain medium; the gain medium is in any one of a rod shape, a strip shape or a sheet shape; the fluorescence lifetime of the gain medium is greater than the seed laser pulse interval.
In a second aspect, an embodiment of the present invention provides a system for suppressing amplified spontaneous emission in a high-gain pulse laser amplifier, including a high-gain pulse laser amplifier, a seed laser, an electro-optic polarization rotator, a first polarization beam splitter, a second polarization beam splitter, a half-wave plate, a faraday rotator combination, and a frequency-division laser absorption cell;
the seed laser is used for outputting polarized short or ultra-short laser pulses;
The electro-optic polarization rotator is used for rotating the polarization direction of the laser pulse screened from the linear polarization short or ultra-short laser pulse output by the seed laser by 90 degrees;
The first polarization beam splitter is used for carrying out polarization frequency division on the laser pulse with the polarization direction rotated by 90 degrees to obtain primarily reflected s-polarized light and transmitted p-polarized light;
the second polarization beam splitter is used for secondarily reflecting the s-polarized light;
the half wave plate and the Faraday rotator are combined, and are used for respectively passing the s-polarized light after secondary reflection and the p-polarized light after transmission on a travelling route comprising a plurality of plane reflectors, so that the high-gain pulse laser amplifier is injected from two opposite travelling directions, and the s-polarized light after secondary reflection is converted into output laser and the p-polarized light after transmission is absorbed into the frequency division laser absorption pool.
Preferably, the left side of the first polarization beam splitter is inclined to form 45 degrees with the horizontal plane, the right side of the second polarization beam splitter is inclined to form 45 degrees with the horizontal plane, and the first polarization beam splitter and the second polarization beam splitter are arranged on the same vertical line.
Preferably, the half-wave plate comprises a first half-wave plate and a second half-wave plate; the Faraday rotator comprises a first Faraday rotator and a second Faraday rotator;
The combination of the first half-wave plate and the first Faraday rotator is used for enabling the polarization direction to rotate 45 degrees to become p-polarized light after entering from the first half-wave plate and exiting from the first Faraday rotator before the s-polarized light after secondary reflection is injected into the high-gain pulse laser amplifier, and entering one side of the high-gain pulse laser amplifier after being reflected by a plane reflector;
The second half-wave plate and the second Faraday rotator are combined, after passing through the high-gain pulse laser amplifier, the second half-wave plate is incident from the second half-wave plate and is emergent from the second Faraday rotator, so that the polarization direction is rotated by 45 degrees to be changed into s-polarized light, and the s-polarized light is reflected by a plane reflector and then reflected by the first polarization beam splitter to output laser.
And injecting the transmitted second laser pulse sequence which passes through the plane reflector into the other side of the high-gain pulse laser amplifier, wherein the rotation angle of the polarization direction of the transmitted second laser pulse sequence is unchanged.
Preferably, the second half-wave plate and the second faraday rotator are combined, and the second half-wave plate and the second faraday rotator are further used for enabling the transmitted p-polarized light to enter the other side of the high-gain pulse laser amplifier after passing through a plurality of plane reflectors and being incident from the second faraday rotator and being emitted from the second half-wave plate, wherein the polarization direction rotation angle is unchanged;
The first half wave plate and the first Faraday rotator combination are further used for enabling the polarization direction rotation angle to be unchanged and still to be p-polarized light after the first half wave plate and the first Faraday rotator combination are reflected by the plane reflector and then enter the first Faraday rotator after the high-gain pulse laser amplifier passes through the plane reflector, and the p-polarized light is transmitted to the plane reflector through the second polarization beam splitter and then reflected to the frequency division laser absorption pool.
Preferably, the high gain pulsed laser amplifier comprises a gain medium; the gain medium is in any one of a rod shape, a strip shape or a sheet shape; the fluorescence lifetime of the gain medium is greater than the seed laser pulse interval.
According to the method and the system for inhibiting amplified spontaneous emission in the high-gain pulse laser amplifier, provided by the embodiment of the invention, useless seed laser pulses after frequency division are injected into the high-gain pulse laser amplifier along two opposite reverse light paths, so that the laser power density in the laser amplifier is ensured to be unchanged all the time to realize ASE inhibition of seed laser frequency division, meanwhile, the gain stability of the laser amplifier is ensured, and the pulse energy and the beam quality of output laser are further kept unchanged.
Drawings
In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to the present invention;
fig. 2 is a schematic diagram of a system for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to the present invention;
fig. 3 is a block diagram of a system for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The technical key point of the invention is that useless seed laser pulse after frequency division is still injected into the high-gain pulse laser amplifier along the reverse light path, thereby realizing ASE inhibition of seed laser frequency division by ensuring that the laser power density in the laser amplifier is always unchanged. Meanwhile, the technology ensures the stability of the gain of the laser amplifier, and further can keep the pulse energy and the beam quality of the output laser unchanged.
The following describes a method and a system for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to the present invention with reference to fig. 1 to 3.
The embodiment of the invention provides a method for inhibiting amplified spontaneous emission in a high-gain pulse laser amplifier. Fig. 1 is a flow chart of a method for suppressing amplified spontaneous emission in a high-gain pulse laser amplifier according to an embodiment of the present invention, as shown in fig. 1, the method includes:
step 110, obtaining linear polarization short or ultra-short laser pulses output by seed laser, and rotating the polarization direction of the laser pulses screened out by an electro-optic polarization rotator by 90 degrees;
Step 120, performing polarization frequency division on the laser pulse with the polarization direction rotated by 90 degrees through a first polarization beam splitter to obtain s polarized light and p polarized light which are reflected once, and secondarily reflecting the s polarized light through a second polarization beam splitter;
And 130, respectively arranging a traveling route comprising a half-wave plate, a Faraday rotator combination and a plurality of plane reflectors, and injecting the s-polarized light after secondary reflection and the p-polarized light after transmission into the high-gain pulse laser amplifier from two opposite traveling directions, so that the s-polarized light after secondary reflection is converted into output laser and the p-polarized light after transmission is absorbed into a frequency division laser absorption pool.
Specifically, the pair of half-wave plates are used in combination with a pair of faraday rotators FR1 and FR2, respectively. After combination, the polarization direction of the linearly polarized laser light incident from the half-wave plate direction and emitted from the Faraday rotator can be rotated by 90 degrees; and for the linear polarized laser emitted from the half-wave plate, the rotation angles of the half-wave plate and the Faraday rotator to the polarization direction are mutually offset, and the polarization direction is unchanged. Thus, both lasers are injected into the laser amplifier with the same polarization.
That is, after the seed laser is divided by the electro-optical polarization rotator and the PBS1 and PBS2, two groups of laser pulse sequences are respectively injected into the laser amplifier from two opposite traveling directions of the laser amplifier, and amplification is obtained at the same time. The optical path structure ensures that the laser power density in the laser amplifier is unchanged all the time, so that ASE (amplified spontaneous emission) generation caused by the reduction of the laser power injected into the amplifier after seed laser frequency reduction is avoided. Therefore, the technical scheme of the invention ensures the gain stability of the laser amplifier and outputs the pulse energy of laser.
Based on any of the above embodiments, the left side of the first polarizing beam splitter is inclined to form 45 ° with the horizontal plane, and the right side of the second polarizing beam splitter is inclined to form 45 ° with the horizontal plane, and the first polarizing beam splitter and the second polarizing beam splitter are disposed on the same vertical line.
Specifically, the polarization beam splitter shown in fig. 2 is a pair of polarization beam splitters PBS1 and PBS2, wherein PBS1 is disposed above PBS2 and on the same vertical line, the left side of PBS1 is inclined at 45 ° to the horizontal, and the right side of PBS2 is inclined at 45 ° to the horizontal.
Based on any of the above embodiments, the half-wave plate includes a first half-wave plate and a second half-wave plate; the Faraday rotator comprises a first Faraday rotator and a second Faraday rotator;
specifically, the half-wave plate shown in fig. 2 is a pair of half-wave plates, and the faraday rotator is a pair of faraday rotators FR1 and FR2.
The s polarized light after secondary reflection and the transmitted p polarized light are respectively injected into the high gain pulse laser amplifier from two opposite advancing directions through arranging advancing routes comprising a half wave plate, a Faraday rotator combination and a plurality of plane reflectors, so that the s polarized light after secondary reflection is converted into output laser and the transmitted p polarized light is absorbed into a frequency division laser absorption pool, and the method comprises the following steps:
Before the secondary reflected s-polarized light is injected into the high-gain pulse laser amplifier, the s-polarized light enters from the first half wave plate and exits from the first Faraday rotator so that the polarization direction is rotated by 45 degrees to become p-polarized light, and the p-polarized light enters one side of the high-gain pulse laser amplifier after being reflected by a plane reflector; after passing through the high-gain pulse laser amplifier, the laser beam enters from the second half-wave plate and exits from the second Faraday rotator so that the polarization direction is rotated by 45 degrees to be changed into s-polarized light, and after being reflected by the plane reflector, the laser beam is reflected and output through the first polarization beam splitter.
Based on any of the above embodiments, the injecting the s-polarized light after the secondary reflection and the p-polarized light after the transmission into the high-gain pulse laser amplifier from two opposite traveling directions through setting traveling routes including a half-wave plate, a faraday rotator combination and a plurality of plane mirrors, respectively, so that the s-polarized light after the secondary reflection is converted into output laser light and the p-polarized light after the transmission is absorbed into a frequency division laser absorption pool, further includes:
Before the transmitted p-polarized light is injected into the high-gain pulse laser amplifier, the p-polarized light enters the other side of the high-gain pulse laser amplifier after passing through a plurality of plane reflectors, enters from the second Faraday rotator and exits from the second half-wave plate, and the polarization direction rotation angle is unchanged; after the high-gain pulse laser amplifier, the high-gain pulse laser amplifier is reflected by a plane mirror, then enters the first Faraday rotator and exits from the first half-wave plate, so that the rotation angle of the polarization direction is unchanged and still becomes p-polarized light, and the p-polarized light is transmitted to the plane mirror through the second polarization beam splitter and then reflected to the frequency division laser absorption pool.
Based on any of the above embodiments, the high gain pulsed laser amplifier includes a gain medium; the gain medium is in any one of a rod shape, a strip shape or a sheet shape; the fluorescence lifetime of the gain medium is greater than the seed laser pulse interval.
Specifically, solid state laser amplifiers are high gain, and thus when no seed laser is injected, amplified Spontaneous Emission (ASE) light of higher power is generated along the laser amplification path.
The high gain pulsed laser amplifier may be polarization dependent (requiring the polarization direction of the injected laser light, e.g., nd: YVO 4) or polarization independent (requiring no polarization direction of the injected laser light, e.g., nd: YAG).
The high gain pulse laser amplifier can be single-stage or multi-stage; the gain medium can be in the shape of one of a bar, a strip and a sheet.
The pulse interval of the seed laser is far smaller than the fluorescence lifetime of the gain medium used by the high-gain pulse laser amplifier.
The system for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to the present invention will be described below, and the method for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier described below and the method for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier described above will be referred to in correspondence with each other.
Fig. 3 is a schematic structural diagram of a system for suppressing spontaneous emission of a high-gain pulse laser amplifier according to an embodiment of the present invention, and as shown in fig. 3, the system includes a high-gain pulse laser amplifier 310, a seed laser 320, an electro-optic polarization rotator 330, a first polarization beam splitter 3401, a second polarization beam splitter 3402, a half-wave plate 350, a faraday rotator 360, and a frequency-division laser absorption cell 370;
The seed laser 320 is used for outputting polarized short or ultra-short laser pulses;
the electro-optic polarization rotator 330 is configured to rotate the polarization direction of the laser pulse selected from the linear polarization short or ultra-short laser pulses outputted from the seed laser by 90 °;
The first polarization beam splitter 3401 is configured to divide the polarization of the laser pulse with the polarization direction rotated by 90 ° to obtain s-polarized light and p-polarized light that are reflected once;
The second polarization beam splitter 3402 is configured to secondarily reflect the s-polarized light;
The half-wave plate 350 and the faraday rotator 360 are combined to enable the s-polarized light after secondary reflection and the p-polarized light after transmission to respectively pass through a traveling route including a plurality of plane mirrors, so that the high-gain pulse laser amplifier 310 is injected from two opposite traveling directions, and the s-polarized light after secondary reflection is converted into output laser light and the p-polarized light after transmission is absorbed into the frequency-division laser absorption pool 370.
Based on any of the above embodiments, as shown in fig. 2, the left side of the first polarizing beam splitter is inclined at 45 ° to the horizontal, the right side of the second polarizing beam splitter is inclined at 45 ° to the horizontal, and the first polarizing beam splitter and the second polarizing beam splitter are disposed on the same vertical line.
Based on any of the above embodiments, the half-wave plate includes a first half-wave plate and a second half-wave plate; the Faraday rotator comprises a first Faraday rotator and a second Faraday rotator;
The combination of the first half-wave plate and the first Faraday rotator is used for enabling the polarization direction to rotate 45 degrees to become p-polarized light after entering from the first half-wave plate and exiting from the first Faraday rotator before the s-polarized light after secondary reflection is injected into the high-gain pulse laser amplifier, and entering one side of the high-gain pulse laser amplifier after being reflected by a plane reflector;
The second half-wave plate and the second Faraday rotator are combined, after passing through the high-gain pulse laser amplifier, the second half-wave plate is incident from the second half-wave plate and is emergent from the second Faraday rotator, so that the polarization direction is rotated by 45 degrees to be changed into s-polarized light, and the s-polarized light is reflected by a plane reflector and then reflected by the first polarization beam splitter to output laser.
And injecting the transmitted second laser pulse sequence which passes through the plane reflector into the other side of the high-gain pulse laser amplifier, wherein the rotation angle of the polarization direction of the transmitted second laser pulse sequence is unchanged.
Based on any of the above embodiments, the combination of the second half-wave plate and the second faraday rotator is further configured to, before the transmitted p-polarized light is injected into the high-gain pulse laser amplifier, pass through a plurality of plane mirrors, and enter the other side of the high-gain pulse laser amplifier from the second faraday rotator, where the polarization direction rotation angle is unchanged after the p-polarized light exits from the second half-wave plate;
The first half wave plate and the first Faraday rotator combination are further used for enabling the polarization direction rotation angle to be unchanged and still to be p-polarized light after the first half wave plate and the first Faraday rotator combination are reflected by the plane reflector and then enter the first Faraday rotator after the high-gain pulse laser amplifier passes through the plane reflector, and the p-polarized light is transmitted to the plane reflector through the second polarization beam splitter and then reflected to the frequency division laser absorption pool.
Based on any of the above embodiments, the high gain pulsed laser amplifier includes a gain medium; the gain medium is in any one of a rod shape, a strip shape or a sheet shape; the fluorescence lifetime of the gain medium is greater than the seed laser pulse interval.
In summary, the present invention discloses a method and a system for suppressing spontaneous emission of a high-gain pulse laser amplifier, wherein the method adopts a technology for suppressing Amplified Spontaneous Emission (ASE) in a high-power solid-state short pulse/ultra-short pulse laser amplifier, and the system comprises: a high gain pulse laser amplifier, seed laser, electro-optic polarization rotator, a pair of polarization splitters (PBS 1 and PBS 2), a pair of Faraday rotators (FR 1 and FR 2), a pair of half-wave plates, a frequency-divided laser absorption cell, and plane mirrors. According to the embodiment of the invention, useless seed laser pulses after frequency division are injected into the high-gain pulse laser amplifier along two opposite reverse light paths, so that the laser power density in the laser amplifier is ensured to be unchanged all the time to realize ASE inhibition of seed laser frequency division, meanwhile, the gain stability of the laser amplifier is ensured, and the pulse energy and the beam quality of output laser can be kept unchanged. In the high-power solid short pulse/ultrashort pulse laser, the invention can be applied to occasions requiring the pulse energy and the beam quality of the output laser to be kept unchanged when the repetition frequency is reduced.
The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, 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. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A method of suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier, comprising:
Obtaining a linear polarization short or ultra-short laser pulse output by seed laser, and rotating the polarization direction of the laser pulse screened by the linear polarization short or ultra-short laser pulse output by the seed laser by 90 degrees through an electro-optic polarization rotator;
Performing polarization frequency division on the laser pulse with the polarization direction rotated by 90 degrees through a first polarization beam splitter to obtain primarily reflected s-polarized light and transmitted p-polarized light, and secondarily reflecting the s-polarized light through a second polarization beam splitter;
The s polarized light after secondary reflection and the transmitted p polarized light are respectively injected into the high-gain pulse laser amplifier from two opposite advancing directions through arranging advancing routes comprising a half wave plate, a Faraday rotator combination and a plurality of plane reflectors, so that the s polarized light after secondary reflection is converted into output laser and the transmitted p polarized light is absorbed into a frequency division laser absorption tank;
the half-wave plate comprises a first half-wave plate and a second half-wave plate; the Faraday rotator comprises a first Faraday rotator and a second Faraday rotator;
The step of injecting the s polarized light after secondary reflection and the p polarized light after transmission into the high gain pulse laser amplifier from two opposite traveling directions through the traveling route comprising a half wave plate, a Faraday rotator combination and a plurality of plane reflectors, respectively, so that the s polarized light after secondary reflection is converted into output laser and the p polarized light after transmission is absorbed into a frequency division laser absorption pool, and the step of including:
Before the s polarized light after secondary reflection is injected into the high-gain pulse laser amplifier, the s polarized light enters from the first half wave plate and exits from the first Faraday rotator so that the polarization direction is rotated by 45 degrees to become p polarized light, and the p polarized light enters one side of the high-gain pulse laser amplifier after being reflected by a first plane reflector; after passing through the high-gain pulse laser amplifier, the laser is incident from the second half-wave plate and emitted from the second Faraday rotator, so that the polarization direction is rotated by 45 degrees to be changed into s-polarized light, and the s-polarized light is reflected by the second plane reflector and the third plane reflector and then reflected by the first polarization beam splitter to output laser;
before the transmitted p-polarized light is injected into the high-gain pulse laser amplifier, the p-polarized light enters the other side of the high-gain pulse laser amplifier after passing through a third plane reflector and a second plane reflector, enters from the second Faraday rotator and exits from the second half-wave plate, and the polarization direction rotation angle is unchanged; after the high-gain pulse laser amplifier, the high-gain pulse laser amplifier is reflected by a first plane reflector, then enters the first Faraday rotator and exits from the first half-wave plate, so that the rotation angle of the polarization direction is unchanged and still becomes p polarized light, and the p polarized light is transmitted to a fourth plane reflector through the second polarization beam splitter and then reflected to the frequency division laser absorption pool.
2. A method of suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to claim 1, wherein the left side of said first polarizing beam splitter is tilted at 45 ° to horizontal and the right side of said second polarizing beam splitter is tilted at 45 ° to horizontal, while said first polarizing beam splitter and said second polarizing beam splitter are disposed on the same vertical line.
3. The method of suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to claim 1, wherein the high-gain pulsed laser amplifier comprises a gain medium; the gain medium is in any one of a rod shape, a strip shape or a sheet shape; the fluorescence lifetime of the gain medium is greater than the seed laser pulse interval.
4. A system for inhibiting amplified spontaneous emission in a high-gain pulse laser amplifier is characterized by comprising the high-gain pulse laser amplifier, seed laser, an electro-optic polarization rotator, a first polarization beam splitter, a second polarization beam splitter, a half wave plate, a Faraday rotator combination and a frequency division laser absorption tank;
the seed laser is used for outputting polarized short or ultra-short laser pulses;
The electro-optic polarization rotator is used for rotating the polarization direction of the laser pulse screened from the linear polarization short or ultra-short laser pulse output by the seed laser by 90 degrees;
The first polarization beam splitter is used for carrying out polarization frequency division on the laser pulse with the polarization direction rotated by 90 degrees to obtain primarily reflected s-polarized light and transmitted p-polarized light;
the second polarization beam splitter is used for secondarily reflecting the s-polarized light;
the half wave plate and Faraday rotator combination is used for respectively passing the s-polarized light after secondary reflection and the p-polarized light after transmission through a travelling route comprising a plurality of plane reflectors, so that the high-gain pulse laser amplifier is injected from two opposite travelling directions, and the s-polarized light after secondary reflection is converted into output laser and the p-polarized light after transmission is absorbed into the frequency division laser absorption pool;
the half-wave plate comprises a first half-wave plate and a second half-wave plate; the Faraday rotator comprises a first Faraday rotator and a second Faraday rotator;
The combination of the first half-wave plate and the first Faraday rotator is used for enabling the polarization direction to rotate 45 degrees to become p-polarized light after entering from the first half-wave plate and exiting from the first Faraday rotator before the s-polarized light after the secondary reflection is injected into the high-gain pulse laser amplifier, and entering one side of the high-gain pulse laser amplifier after being reflected by the first plane reflector;
The second half-wave plate and the second Faraday rotator are combined, and are used for enabling p polarized light after passing through the high-gain pulse laser amplifier to be incident from the second half-wave plate and to be emitted from the second Faraday rotator so that the polarization direction is rotated by 45 degrees to be changed into s polarized light, and the s polarized light is reflected by the second plane reflector and the third plane reflector and then reflected by the first polarization beam splitter to output laser;
the second half-wave plate and the second Faraday rotator are combined, and are also used for leading the transmitted p-polarized light to enter the other side of the high-gain pulse laser amplifier after entering from the second Faraday rotator and exiting from the second half-wave plate after passing through a third plane reflector and a second plane reflector before the transmitted p-polarized light is injected into the high-gain pulse laser amplifier, wherein the polarization direction rotation angle is unchanged;
The first half wave plate and the first Faraday rotator are combined, and the p-polarized light after passing through the high-gain pulse laser amplifier is reflected by the first plane reflector, enters the first Faraday rotator and exits the first half wave plate, so that the rotation angle of the polarization direction is unchanged, and is still p-polarized light, and the p-polarized light is transmitted to the fourth plane reflector through the second polarization beam splitter and then reflected to the frequency division laser absorption pool.
5. The system for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to claim 4, wherein said first polarizing beam splitter is tilted to the left by 45 ° and said second polarizing beam splitter is tilted to the right by 45 ° and said first polarizing beam splitter and said second polarizing beam splitter are disposed on the same vertical line.
6. The system for suppressing amplified spontaneous emission in a high-gain pulsed laser amplifier according to claim 4, wherein said high-gain pulsed laser amplifier comprises a gain medium; the gain medium is in any one of a rod shape, a strip shape or a sheet shape; the fluorescence lifetime of the gain medium is greater than the seed laser pulse interval.
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