CN115084990A - Optical amplifier and pulse laser device - Google Patents
Optical amplifier and pulse laser device Download PDFInfo
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- CN115084990A CN115084990A CN202210774544.8A CN202210774544A CN115084990A CN 115084990 A CN115084990 A CN 115084990A CN 202210774544 A CN202210774544 A CN 202210774544A CN 115084990 A CN115084990 A CN 115084990A
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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
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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
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
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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
- H01S3/10061—Polarization control
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Abstract
The invention discloses an optical amplifier and a pulse laser device. The optical amplifier comprises a pumping source, a laser crystal and a light beam modulation unit, wherein the light beam modulation unit comprises a plurality of reflecting surfaces; the light beam to be amplified is incident to the light beam modulation unit, changes the transmission direction when being reflected by the reflecting surface, and passes through the laser crystal for four times; the pump source is used for emitting pump light to the laser crystal, and the laser crystal absorbs the pump light to realize four-way amplification of the light beam to be amplified. According to the technical scheme, the seed light is amplified in four ways by using a simple amplification structure design, the generation of self-oscillation of the seed light is inhibited, meanwhile, the high-gain amplification of the seed light with different energy is realized, and the guarantee is provided for the high efficiency of subsequent further power amplification.
Description
Technical Field
The present invention relates to the field of optical technology, and in particular, to an optical amplifier and a pulsed laser device.
Background
The pulse laser has been widely used in the fields of material fine micromachining, semiconductor industry, solar photovoltaic, scientific research and the like due to its extremely high peak power and narrow pulse width.
High power pulsed lasers are typically generated by using a seed source to output seed pulses, which are then power amplified using an optical amplifier. For example, the picosecond laser technology that is now popular is: and a seed source is adopted to carry out traveling wave one-way or multi-way solid amplification to realize picosecond laser pulse output with high monopulse energy and controllable frequency. However, the mode of traveling wave amplification has low energy utilization rate and larger volume, and is not beneficial to the development of current structure miniaturization.
Disclosure of Invention
The invention provides an optical amplifier and a pulse laser device, wherein the optical amplifier realizes four-way amplification of seed light by using a simple amplification structure design, inhibits the self-oscillation generation of the seed light, realizes high-gain amplification of the seed light with different energy and guarantees the high efficiency of subsequent further power amplification.
According to an aspect of the present invention, there is provided an optical amplifier including a pump source, a laser crystal, and a beam modulation unit including a plurality of reflective surfaces;
the light beam to be amplified enters the light beam modulation unit, changes the transmission direction when being reflected by the reflecting surface, and passes through the laser crystal for four times;
the pump source is used for emitting pump light to the laser crystal, and the laser crystal absorbs the pump light to realize four-way amplification of the light beam to be amplified.
Optionally, when the light beam to be amplified passes through the laser crystal, paths of the light beam passing through the laser crystal at least twice coincide.
Optionally, the light beam paths passing through the laser crystal for four times coincide;
the light beam modulation unit comprises an isolator, a polarization spectroscope, a Faraday rotator, a half-wave plate and a first reflection surface which are arranged along a first direction and on the same optical axis, and the light beam modulation unit also comprises a second reflection surface which is arranged along a second direction and on the same optical axis with the polarization spectroscope, wherein the first direction is crossed with the second direction;
the light beam to be amplified in the first polarization direction enters the first end of the isolator, exits through the second end of the isolator, enters the polarization spectroscope for transmission, passes through the laser crystal for the first time after being transmitted by the Faraday rotator and the half-wave plate, passes through the laser crystal for the second time after being reflected by the first reflecting surface, and is converted into the light beam in the second polarization direction after being transmitted by the half-wave plate and the Faraday rotator again;
the light beam in the second polarization direction enters the polarization beam splitter to be reflected, is reflected by the second reflection surface and then enters the polarization beam splitter to be reflected, passes through the laser crystal for the third time after being transmitted by the Faraday rotator and the half-wave plate, passes through the laser crystal for the fourth time after being reflected by the first reflection surface, and is converted into the light beam in the first polarization direction after being transmitted by the half-wave plate and the Faraday rotator again;
and the light beam with the first polarization direction passes through the polarization beam splitter, is transmitted to the second end of the isolator, and is output from the third end of the isolator.
Optionally, the light beam paths passing through the laser crystal for the first time and the second time coincide with each other, and the light beam paths passing through the laser crystal for the third time and the fourth time coincide with each other;
the light beam modulation unit comprises a first polarization spectroscope, a Faraday rotator, a half-wave plate and a first reflection surface which are arranged along a first direction coaxial axis, and further comprises a first reflection mirror and a second reflection mirror, wherein the first reflection mirror and the second reflection mirror are positioned on the same side of the first polarization spectroscope, and are positioned on two sides adjacent to the first polarization spectroscope together with the Faraday rotator;
the light beam to be amplified in the first polarization direction is emitted to the first polarization spectroscope from a first position to be transmitted, passes through the laser crystal for the first time after being transmitted by the Faraday rotator and the half-wave plate, passes through the laser crystal for the second time after being reflected by the first reflection surface, and is converted into the light beam in the second polarization direction after being transmitted by the half-wave plate and the Faraday rotator again;
the light beam in the second polarization direction enters the first polarization beam splitter to be reflected, is sequentially reflected by the first reflecting mirror and the second reflecting mirror and then enters the first polarization beam splitter to be reflected, passes through the laser crystal for the third time after being transmitted by the Faraday rotator and the half-wave plate, passes through the laser crystal for the fourth time after being reflected by the first reflecting surface, and is converted into the light beam in the first polarization direction after being transmitted by the half-wave plate and the Faraday rotator again;
and the light beam with the first polarization direction is transmitted through the first polarization beam splitter and is output from a second position.
Optionally, the polarization beam splitter is located between the half-wave plate and the laser crystal, and is on a beam path passing through the laser crystal for the first time and the second time.
Optionally, the beam paths passing through the laser crystal for the third time and the fourth time are overlapped;
the light beam modulation unit comprises a polarization beam splitter, a first one-half wave plate, a Faraday rotator, a second one-half wave plate, a converging lens and a first reflection surface, wherein the polarization beam splitter, the first one-half wave plate, the Faraday rotator, the second one-half wave plate, the converging lens and the first reflection surface are arranged along a first direction coaxial axis, the extension length of the first one-half wave plate is greater than that of the second one-half wave plate, the light beam modulation unit further comprises a third reflector and a fourth reflector, the third reflector and the fourth reflector are positioned on the same side of the polarization beam splitter, and the third reflector and the fourth reflector are positioned on two sides adjacent to the polarization beam splitter;
the light beam to be amplified in the first polarization direction is incident to the polarization beam splitter from a first position and is transmitted, is incident to the converging lens after being transmitted by the first one-half wave plate and the Faraday rotator, is obliquely incident at a first incident angle after being converged by the converging lens, passes through the laser crystal for the first time, is reflected by the first reflecting surface, passes through the laser crystal for the second time, is transmitted by the converging lens, the Faraday rotator and the first one-half wave plate again, and is converted into a light beam in the second polarization direction;
the light beam in the second polarization direction enters the polarization beam splitter to be reflected, is sequentially reflected by the third reflector and the fourth reflector and then enters the polarization beam splitter to be reflected, passes through the laser crystal for the third time after being transmitted by the Faraday rotator, the second half-wave plate and the converging lens, passes through the laser crystal for the fourth time after being reflected by the first reflecting surface, and is converted into the light beam in the first polarization direction after being transmitted by the converging lens, the second half-wave plate and the Faraday rotator again;
and the light beam with the first polarization direction is transmitted through the polarization beam splitter and is output from a second position.
Optionally, the beam paths passing through the laser crystal for the third time and the fourth time are overlapped;
the light beam modulation unit comprises a fifth reflector, a sixth reflector, an isolator and a first reflecting surface;
the light beam to be amplified obliquely enters the laser crystal at a second incident angle and passes through the laser crystal for the first time, after being reflected by the first reflecting surface, the light beam passes through the laser crystal for the second time, then enters the isolator from the first end after being reflected by the fifth reflecting mirror and the sixth reflecting mirror in sequence, passes through the laser crystal for the third time after being emitted from the second end, passes through the laser crystal for the fourth time after being reflected by the first reflecting surface, then enters the isolator from the second end, and is emitted from the third end.
Optionally, the light beam paths passing through the laser crystal for four times are not overlapped;
the light beam modulation unit comprises a polarization beam splitter, a third half wave plate, a Faraday rotator, a fourth half wave plate, a converging lens and a first reflection surface which are arranged along a first direction coaxial axis, wherein the extension length of the third half wave plate is greater than that of the fourth half wave plate, the light beam modulation unit further comprises a seventh reflector and an eighth reflector, the seventh reflector and the eighth reflector are positioned on the same side of the polarization beam splitter, and the seventh reflector and the eighth reflector are positioned on two sides adjacent to the polarization beam splitter;
the light beam to be amplified in the first polarization direction is incident to the polarization beam splitter from a first position and is transmitted, is incident to the converging lens after being transmitted by the third half-wave plate and the Faraday rotator, is obliquely incident at a third incident angle after being converged by the converging lens, passes through the laser crystal for the first time, is reflected by the first reflecting surface, passes through the laser crystal for the second time, is transmitted by the converging lens, the Faraday rotator and the third half-wave plate again, and is converted into a light beam in the second polarization direction;
the light beam in the second polarization direction enters the polarization beam splitter to be reflected, is sequentially reflected by the seventh reflector and the eighth reflector and then enters the polarization beam splitter to be reflected, obliquely enters at a fourth incidence angle after being transmitted by the Faraday rotator, the fourth half-wave plate and the converging lens, passes through the laser crystal for the third time, is reflected by the first reflection surface for the fourth time, passes through the converging lens, the fourth half-wave plate and the Faraday rotator again, and is converted into the light beam in the first polarization direction, wherein the fourth incidence angle is smaller than the third incidence angle;
and the light beam with the first polarization direction is transmitted through the polarization beam splitter and is output from a second position.
Optionally, the reflecting surface is a reflecting surface of a device in the beam modulation unit and/or a reflecting surface of a mirror.
Optionally, the laser device further comprises a pumping lens group located between the pumping source and the laser crystal, and the pumping lens group is configured to converge the pumping light to the laser crystal.
Optionally, the pump light is incident on the laser crystal from one end and/or at least one sidewall of the laser crystal.
According to another aspect of the present invention, there is provided a pulsed laser device comprising the above-described optical amplifier.
The technical scheme of the embodiment of the invention comprises a pumping source, a laser crystal and a light beam modulation unit, wherein the light beam modulation unit comprises a plurality of reflecting surfaces; the pump light is provided for the laser crystal through the pump source, the transmission direction of the light beam to be amplified is changed when the light beam to be amplified is reflected by the reflecting surface of the light beam modulation unit, and four-pass amplification of the light beam to be amplified is realized through the laser crystal for four times. The optical amplifier structure can realize high-gain amplification of seed light with different energies while inhibiting the generation of self-oscillation, thereby ensuring the high efficiency of subsequent further power amplification.
It should be understood that the statements in this section are not intended to identify key or critical features of the embodiments of the present invention, nor are they intended to limit the scope of the invention. Other features of the present invention will become apparent from the following description.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an optical amplifier according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another optical amplifier provided in an embodiment of the present invention;
fig. 3 and fig. 4 are schematic structural diagrams of another optical amplifier according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In order to solve the problems of low energy utilization rate and large volume of the conventional traveling wave amplifier, the embodiment of the invention provides an optical amplifier, which comprises a pumping source, a laser crystal and a light beam modulation unit, wherein the light beam modulation unit comprises a plurality of reflecting surfaces; the light beam to be amplified is incident to the light beam modulation unit, changes the transmission direction when being reflected by the reflecting surface, and passes through the laser crystal for four times; the pump source is used for emitting pump light to the laser crystal, and the laser crystal absorbs the pump light to realize four-way amplification of the light beam to be amplified.
The technical scheme of the embodiment of the invention can be suitable for picosecond pulse lasers, the pump light is provided for the laser crystal through the pump source, the transmission direction of the light beam to be amplified is changed when the light beam to be amplified is reflected by the reflecting surface of the light beam modulation unit, and the four-pass amplification of the light beam to be amplified is realized after the light beam to be amplified passes through the laser crystal for four times. The optical amplifier structure can realize high-gain amplification of seed light with different energies while inhibiting the generation of self-oscillation, thereby ensuring the high efficiency of subsequent further power amplification.
The structure of the optical amplifier provided by the embodiments of the present invention is described below with reference to specific embodiments and drawings, where the number of devices and the positional relationship shown in the drawings are only schematic, and in the case of achieving the same function, it is within the scope of the embodiments of the present invention to appropriately add or reduce some devices, adjust the relative positions of the devices, or combine the embodiments with each other.
Optionally, when the light beam to be amplified passes through the laser crystal, paths of the light beam passing through the laser crystal at least twice coincide.
Fig. 1 is a schematic structural diagram of an optical amplifier according to an embodiment of the present invention. Referring to fig. 1, the optical amplifier provided in this embodiment includes a pump source 10, a laser crystal 20, and a beam modulation unit 30, where the beam modulation unit 30 includes an isolator 31, a polarization beam splitter 32, a faraday rotator 33, a half-wave plate 34, and a first reflection surface 35 that are coaxially arranged along a first direction x, and the beam modulation unit 30 further includes a second reflection surface 36 that is coaxially arranged with the polarization beam splitter 32 along a second direction y, where the first direction x intersects the second direction y.
The pump source 10 may be a semiconductor laser diode LD, for example, an LD having an output wavelength of 880nm, 888nm, or 914nm and a power of 120W, and may output light from an optical fiber having a core diameter of 200 μm and a numerical aperture NA of 0.22. The laser crystal 20 may be doped with Nd: YV04 at 0.3% or doped with Nd: YAG at 1%. The isolator 31 is a one-way transmission device for ensuring one-way transmission of the light beam, which allows only light to propagate from the entrance port (first end) to the exit port (second end), and prevents light propagating from the exit port (second end) to the entrance port (first end) from being output from the side (third end). The polarizing beamsplitter 32 transmits light of one polarization direction (e.g., horizontally polarized light) and reflects light of the other polarization direction (e.g., vertically polarized light), for example, UVFS material, which may be 25.4mm by 25.4mm, with a clear aperture greater than 80%, using a polarizing beamsplitter PBS with a wavelength of 1064 nm. The faraday rotator 33 has an optical rotation function for rotating the polarization direction by 45 ° when the light beam is transmitted, and the half-wave plate 34 is used for making the light perform axial symmetry transformation to the polarization direction of the light according to the optical axis of the wave plate, and in the specific implementation, the positions of the faraday rotator 33 and the half-wave plate 34 can be interchanged. The first reflection surface 35 and the second reflection surface 36 shown in fig. 1 are both reflection surfaces in a mirror, which is only schematic, and in a specific implementation process, the reflection surface is optionally a reflection surface of a device in the light beam modulation unit and/or a reflection surface of a mirror. For example, in other embodiments, the right surface of the laser crystal 20 may be a first reflection surface, and the lower surface of the polarization beam splitter 32 may be a second reflection surface, that is, at least one of the first reflection surface and the second reflection surface may be a reflection surface of a separately disposed mirror, or a device surface at a corresponding position may be a reflection surface. In the following embodiments, the reflective surface is taken as an example of a reflective surface of a mirror provided separately.
FIG. 1 also schematically illustrates a light transmission diagram, with continued reference to FIG. 1, with the beam paths through the laser crystal 20 four times coincident; a light beam to be amplified in a first polarization direction (for example, a horizontal polarization direction) enters a first end a of the isolator 31, exits through a second end b of the isolator 31, enters the polarization beam splitter 32, is transmitted, passes through the laser crystal 20 for the first time after being transmitted by the faraday rotator 33 and the half-wave plate 34, is reflected by the first reflection surface 35, passes through the laser crystal 20 for the second time, is transmitted by the half-wave plate 34 and the faraday rotator 33 again, and is converted into a light beam in a second polarization direction (for example, a vertical polarization direction);
the light beam in the second polarization direction enters the polarization beam splitter 32 to be reflected, is reflected by the second reflection surface 36 and then enters the polarization beam splitter 32 to be reflected, passes through the laser crystal 20 for the third time after being transmitted by the faraday rotator 33 and the half-wave plate 34, passes through the laser crystal 20 for the fourth time after being reflected by the first reflection surface 35, and is converted into the light beam in the first polarization direction after being transmitted by the half-wave plate 34 and the faraday rotator 33 again;
the light beam with the first polarization direction is transmitted to the second end b of the isolator 31 through the polarization beam splitter 32 and is output from the third end c of the isolator 31.
Most of the devices of the optical amplifier provided by this embodiment are located on the same optical axis, and the light beam paths passing through the laser crystal 20 for four times coincide, so that the optical amplifier has a compact structure, and is beneficial to reducing the volume of the optical amplifier.
Fig. 2 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention. Referring to fig. 2, the light beam modulation unit 30 includes a first polarization beam splitter 32, a faraday rotator 33, a half-wave plate 34, and a first reflection surface 35 arranged along the first direction x coaxial axis, and the light beam modulation unit 30 further includes a first reflection mirror 361 and a second reflection mirror 362, the first reflection mirror 361 and the second reflection mirror 362 being located on the same side of the first polarization beam splitter 32 and located on two sides adjacent to the first polarization beam splitter 32 with the faraday rotator 33.
FIG. 2 also schematically illustrates a light transmission diagram, with continued reference to FIG. 2, where the beam paths for the first and second passes through laser crystal 20 coincide, and the beam paths for the third and fourth passes through laser crystal 20 coincide; the light beam to be amplified in the first polarization direction enters the first polarization beam splitter 32 from the first position d to be transmitted, passes through the laser crystal 20 for the first time after being transmitted by the faraday rotator 33 and the half-wave plate 34, passes through the laser crystal 20 for the second time after being reflected by the first reflection surface 35, and is converted into the light beam in the second polarization direction after being transmitted by the half-wave plate 34 and the faraday rotator 33 again;
the light beam in the second polarization direction enters the first polarization beam splitter 32 to be reflected, is sequentially reflected by the first reflecting mirror 361 and the second reflecting mirror 362 and then enters the first polarization beam splitter 32 to be reflected, passes through the laser crystal 20 for the third time after being transmitted by the faraday rotator 33 and the half-wave plate 34, passes through the laser crystal 20 for the fourth time after being reflected by the first reflecting surface 35, and is converted into the light beam in the first polarization direction after being transmitted by the half-wave plate 34 and the faraday rotator 33 again;
the light beam with the first polarization direction is transmitted through the first pbs 32 and output from the second position e.
The optical amplifier provided by the embodiment is provided with the superposition of the light beam paths passing through the laser crystal 20 for the first time and the second time, and the superposition of the light beam paths passing through the laser crystal 20 for the third time and the fourth time, so that the position of the light beam to be amplified passing through the laser crystal 20 can be increased on the basis of compact structure of the optical amplifier, and the amplification efficiency can be improved.
Fig. 3 and fig. 4 are schematic structural diagrams of another optical amplifier according to an embodiment of the present invention, and referring to fig. 3 and fig. 4, based on the embodiment shown in fig. 2, the optical amplifier further includes a second polarization beam splitter 38 located between the half-wave plate 34 and the laser crystal 20 and on the beam path passing through the laser crystal 20 for the first time and the second time, the second polarization beam splitter 38 can prevent the light from returning to the broken optical path, and improve the performance of the optical amplifier.
Fig. 5 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention. Referring to fig. 5, the light beam modulation unit 30 includes a polarization beam splitter 32, a first half wave plate 341, a faraday rotator 33, a second half wave plate 342, a converging lens 37, and a first reflection surface 35 arranged along a first direction x coaxial axis, wherein an extension length of the first half wave plate 341 is greater than an extension length of the second half wave plate 342, an extension direction of the first half wave plate 341 and the second half wave plate 342 is perpendicular to the first direction x, the light beam modulation unit 30 further includes a third mirror 363 and a fourth mirror 364, the third mirror 363 and the fourth mirror 364 are located on the same side of the polarization beam splitter 32, and are located on two sides adjacent to the polarization beam splitter 32 with the first half wave plate 341.
FIG. 5 also schematically illustrates a light transmission diagram, with continued reference to FIG. 5, where the beam paths for the third and fourth passes through laser crystal 20 coincide; the light beam to be amplified in the first polarization direction enters the polarization beam splitter 32 from the first position d and is transmitted, enters the converging lens 37 after being transmitted by the first half-wave plate 341 and the faraday rotator 33, obliquely enters the laser crystal 20 at the first incident angle alpha after being converged by the converging lens 37, passes through the laser crystal 20 for the second time after being reflected by the first reflecting surface 35, and is transmitted by the converging lens 37, the faraday rotator 33 and the first half-wave plate 341 again and then is converted into the light beam in the second polarization direction;
the light beam in the second polarization direction enters the polarization beam splitter 32 to be reflected, and then sequentially reflected by the third reflector 363 and the fourth reflector 364 and then enters the polarization beam splitter 32 to be reflected, and then passes through the laser crystal 20 (vertical incidence) for the third time after being transmitted by the faraday rotator 33, the second half-wave plate 342 and the converging lens 37, and then passes through the laser crystal 20 for the fourth time after being reflected by the first reflecting surface 35, and is converted into the light beam in the first polarization direction after being transmitted by the converging lens 37, the second half-wave plate 342 and the faraday rotator 33 again;
the light beam with the first polarization direction is transmitted through the polarization splitting prism 32 and output from the second position e.
Fig. 6 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention, and referring to fig. 6, different from fig. 5, in this embodiment, an isolator 31 is added to change an emitting direction of emitted light, and other structures are the same as those of the embodiment in fig. 5.
Similar to the structure shown in fig. 5, in another embodiment, it can be designed that the beam paths passing through the laser crystal for the third time and the fourth time do not coincide, that is, the beam paths passing through the laser crystal for the fourth time do not coincide. Fig. 7 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention. Referring to fig. 7, the beam modulation unit 30 includes a polarization beam splitter 32, a third half-wave plate 343, a faraday rotator 33, a fourth half-wave plate 344, a converging lens 37, and a first reflection surface 35 arranged along the first direction x coaxial axis, the third half-wave plate 343 having an extended length greater than that of the fourth half-wave plate 344, and the beam modulation unit 30 further includes a seventh mirror 367 and an eighth mirror 368, the seventh mirror 367 and the eighth mirror 368 being located on the same side of the polarization beam splitter 32 and on both sides adjacent to the polarization beam splitter 32 as the third half-wave plate 343.
Fig. 7 further schematically shows a light transmission diagram, and with reference to fig. 7, a light beam to be amplified in the first polarization direction enters the polarization beam splitter 32 from the first position d and is transmitted, and then enters the converging lens 37 after being transmitted by the third half-wave plate 343 and the faraday rotator 33, and then obliquely enters the first laser beam passing through the laser crystal 20 at the third incident angle γ after being converged by the converging lens 37, and after being reflected by the first reflection surface 35, the first laser beam passes through the laser crystal 20 for the second time, and after being transmitted by the converging lens 37, the faraday rotator 33 and the third half-wave plate 343 again, the first laser beam is converted into a light beam in the second polarization direction;
the light beam in the second polarization direction enters the polarization beam splitter 32 to be reflected, and then sequentially reflected by the seventh reflecting mirror 367 and the eighth reflecting mirror 368 and further enters the polarization beam splitter 32 to be reflected, and then obliquely enters the laser crystal 20 at a fourth incident angle δ after being transmitted by the faraday rotator 33, the fourth half-wave plate 344 and the converging lens 37, and then passes through the laser crystal 20 for the fourth time after being reflected by the first reflecting surface 35, and is converted into the light beam in the first polarization direction after being transmitted by the converging lens 37, the fourth half-wave plate 344 and the faraday rotator 33 again, wherein the fourth incident angle δ is smaller than the third incident angle γ;
the light beam with the first polarization direction is transmitted through the polarization splitting prism 32 and output from the second position e.
In specific implementation, a reflecting mirror may be further disposed on the left side of the polarization beam splitter 32 to change the transmission direction of the light beam, or an isolator may be disposed, which may be designed according to actual situations in specific implementation, and the embodiment of the present invention is not limited.
Fig. 8 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention. Referring to fig. 8, the beam modulation unit includes a fifth mirror 365, a sixth mirror 366, an isolator 31, and a first reflection surface 35; wherein the beam paths passing through the laser crystal 20 for the third and fourth times coincide.
The light beam to be amplified obliquely enters the laser crystal 20 at a second incident angle β, passes through the laser crystal 20 for the first time after being reflected by the first reflecting surface 35, enters the isolator 31 from the first end a after being reflected by the fifth reflecting mirror 365 and the sixth reflecting mirror 366 in sequence, passes through the laser crystal 20 (vertical incidence) for the third time after exiting from the second end b, passes through the laser crystal 20 for the fourth time after being reflected by the first reflecting surface 35, enters the isolator 31 from the second end b, and exits from the third end c.
In a specific implementation, the light beam to be amplified obliquely incident on the laser crystal 20 at the second incident angle β may change a light beam transmission path by reflection of a mirror, which is not limited in the embodiment of the present invention.
Fig. 9 is a schematic structural diagram of another optical amplifier according to an embodiment of the present invention. Referring to fig. 9, optionally, the optical amplifier further includes a pumping lens group 40 located between the pumping source 10 and the laser crystal 20, and the pumping lens group 40 is configured to focus the pumping light to the laser crystal 20.
The pumping lens group 40 may include at least one lens having a light converging function, and by disposing the pumping lens group 40, the efficiency of coupling the pumping light to the laser crystal 20 may be improved. In practical implementation, the relative position relationship between the pump source 10 and the laser crystal 20 can be designed according to practical situations, and optionally, the pump light is incident on the laser crystal 20 from one end and/or at least one side wall of the laser crystal 20. For example, referring to fig. 1 to 8, the pump light may be incident from one end of the laser crystal 20, or as shown in fig. 9, the pump light may be incident from one sidewall of the laser crystal 20, and in other embodiments, two or more pump sources 10 may be further provided, which is not limited in this embodiment of the present invention.
The embodiment of the invention also provides a pulse laser device which comprises any one of the optical amplifiers provided by the embodiment.
Since the pulsed laser device provided by the embodiment of the present invention includes any one of the optical amplifiers provided by the above embodiments, the same or corresponding technical effects as those of the optical amplifier are achieved, and detailed descriptions thereof are omitted here.
The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (12)
1. An optical amplifier is characterized by comprising a pumping source, a laser crystal and a beam modulation unit, wherein the beam modulation unit comprises a plurality of reflecting surfaces;
the light beam to be amplified enters the light beam modulation unit, changes the transmission direction when being reflected by the reflecting surface, and passes through the laser crystal for four times;
the pump source is used for emitting pump light to the laser crystal, and the laser crystal absorbs the pump light to realize four-way amplification of the light beam to be amplified.
2. The optical amplifier of claim 1, wherein the beam paths of the light beam to be amplified that pass through the laser crystal at least twice coincide as the light beam passes through the laser crystal.
3. The optical amplifier of claim 2, wherein the beam paths that pass four times through the laser crystal coincide;
the light beam modulation unit comprises an isolator, a polarization spectroscope, a Faraday rotator, a half-wave plate and a first reflection surface which are arranged along a first direction coaxial axis, the light beam modulation unit also comprises a second reflection surface which is arranged along a second direction coaxial axis with the polarization spectroscope, and the first direction is crossed with the second direction;
the light beam to be amplified in the first polarization direction enters the first end of the isolator, exits from the second end of the isolator, enters the polarization beam splitter for transmission, passes through the laser crystal for the first time after being transmitted by the Faraday rotator and the half-wave plate, passes through the laser crystal for the second time after being reflected by the first reflecting surface, and is converted into the light beam in the second polarization direction after being transmitted by the half-wave plate and the Faraday rotator again;
the light beam in the second polarization direction enters the polarization beam splitter to be reflected, is reflected by the second reflection surface and then enters the polarization beam splitter to be reflected, passes through the laser crystal for the third time after being transmitted by the Faraday rotator and the half-wave plate, passes through the laser crystal for the fourth time after being reflected by the first reflection surface, and is converted into the light beam in the first polarization direction after being transmitted by the half-wave plate and the Faraday rotator again;
and the light beam with the first polarization direction passes through the polarization beam splitter, is transmitted to the second end of the isolator, and is output from the third end of the isolator.
4. The optical amplifier of claim 2 wherein the beam paths of the first and second passes through the laser crystal coincide, and the beam paths of the third and fourth passes through the laser crystal coincide;
the light beam modulation unit comprises a first polarization spectroscope, a Faraday rotator, a half-wave plate and a first reflection surface which are arranged along a first direction coaxial axis, and further comprises a first reflection mirror and a second reflection mirror, wherein the first reflection mirror and the second reflection mirror are positioned on the same side of the first polarization spectroscope, and are positioned on two sides adjacent to the first polarization spectroscope together with the Faraday rotator;
the light beam to be amplified in the first polarization direction is incident to the first polarization spectroscope from a first position and is transmitted, passes through the laser crystal for the first time after being transmitted by the Faraday rotator and the half-wave plate, is reflected by the first reflecting surface, passes through the laser crystal for the second time, passes through the half-wave plate and the Faraday rotator again, and is converted into the light beam in the second polarization direction;
the light beam in the second polarization direction enters the first polarization beam splitter to be reflected, is sequentially reflected by the first reflecting mirror and the second reflecting mirror and then enters the first polarization beam splitter to be reflected, passes through the laser crystal for the third time after being transmitted by the Faraday rotator and the half-wave plate, passes through the laser crystal for the fourth time after being reflected by the first reflecting surface, and is converted into the light beam in the first polarization direction after being transmitted by the half-wave plate and the Faraday rotator again;
and the light beam with the first polarization direction is transmitted through the first polarization beam splitter and is output from a second position.
5. The optical amplifier of claim 4, further comprising a second PBS disposed in a beam path between the half-wave plate and the laser crystal and passing through the laser crystal for the first and second times.
6. The optical amplifier of claim 2, wherein the beam paths of the third and fourth passes through the laser crystal coincide;
the light beam modulation unit comprises a polarization beam splitter, a first one-half wave plate, a Faraday rotator, a second one-half wave plate, a converging lens and a first reflection surface, wherein the polarization beam splitter, the first one-half wave plate, the Faraday rotator, the second one-half wave plate, the converging lens and the first reflection surface are arranged along a first direction coaxial axis, the extension length of the first one-half wave plate is greater than that of the second one-half wave plate, the light beam modulation unit further comprises a third reflector and a fourth reflector, the third reflector and the fourth reflector are positioned on the same side of the polarization beam splitter, and the third reflector and the fourth reflector are positioned on two sides adjacent to the polarization beam splitter;
the light beam to be amplified in the first polarization direction is incident to the polarization beam splitter from a first position and is transmitted, is incident to the converging lens after being transmitted by the first one-half wave plate and the Faraday rotator, is obliquely incident at a first incident angle after being converged by the converging lens, passes through the laser crystal for the first time, is reflected by the first reflecting surface, passes through the laser crystal for the second time, is transmitted by the converging lens, the Faraday rotator and the first one-half wave plate again, and is converted into a light beam in the second polarization direction;
the light beam in the second polarization direction enters the polarization beam splitter to be reflected, is sequentially reflected by the third reflector and the fourth reflector and then enters the polarization beam splitter to be reflected, passes through the laser crystal for the third time after being transmitted by the Faraday rotator, the second half-wave plate and the converging lens, passes through the laser crystal for the fourth time after being reflected by the first reflecting surface, and is converted into the light beam in the first polarization direction after being transmitted by the converging lens, the second half-wave plate and the Faraday rotator again;
and the light beam in the first polarization direction is transmitted by the polarization beam splitter and is output from a second position.
7. The optical amplifier of claim 2, wherein the beam paths of the third and fourth passes through the laser crystal coincide;
the light beam modulation unit comprises a fifth reflector, a sixth reflector, an isolator and a first reflecting surface;
the light beam to be amplified obliquely enters the laser crystal at a second incident angle and passes through the laser crystal for the first time, after being reflected by the first reflecting surface, the light beam passes through the laser crystal for the second time, then enters the isolator from the first end after being reflected by the fifth reflecting mirror and the sixth reflecting mirror in sequence, passes through the laser crystal for the third time after being emitted from the second end, passes through the laser crystal for the fourth time after being reflected by the first reflecting surface, then enters the isolator from the second end, and is emitted from the third end.
8. The optical amplifier of claim 1, wherein the beam paths passing through the laser crystal four times do not coincide;
the light beam modulation unit comprises a polarization beam splitter, a third half wave plate, a Faraday rotator, a fourth half wave plate, a converging lens and a first reflection surface which are arranged along a first direction coaxial axis, wherein the extension length of the third half wave plate is greater than that of the fourth half wave plate, the light beam modulation unit further comprises a seventh reflector and an eighth reflector, the seventh reflector and the eighth reflector are positioned on the same side of the polarization beam splitter, and the seventh reflector and the eighth reflector are positioned on two sides adjacent to the polarization beam splitter;
the light beam to be amplified in the first polarization direction is incident to the polarization beam splitter from a first position and is transmitted, is incident to the converging lens after being transmitted by the third half-wave plate and the Faraday rotator, is obliquely incident at a third incident angle after being converged by the converging lens, passes through the laser crystal for the first time, is reflected by the first reflecting surface, passes through the laser crystal for the second time, is transmitted by the converging lens, the Faraday rotator and the third half-wave plate again, and is converted into a light beam in the second polarization direction;
the light beam in the second polarization direction enters the polarization beam splitter to be reflected, is sequentially reflected by the seventh reflector and the eighth reflector and then enters the polarization beam splitter to be reflected, obliquely enters at a fourth incidence angle after being transmitted by the Faraday rotator, the fourth half-wave plate and the converging lens, passes through the laser crystal for the third time, is reflected by the first reflection surface for the fourth time, passes through the converging lens, the fourth half-wave plate and the Faraday rotator again, and is converted into the light beam in the first polarization direction, wherein the fourth incidence angle is smaller than the third incidence angle;
and the light beam with the first polarization direction is transmitted through the polarization beam splitter and is output from a second position.
9. The optical amplifier according to claim 1, wherein the reflecting surface is a reflecting surface of a device and/or a reflecting mirror in the beam modulating unit.
10. The optical amplifier of claim 1, further comprising a pump lens group between the pump source and the laser crystal, the pump lens group configured to focus the pump light onto the laser crystal.
11. The optical amplifier of claim 1, wherein the pump light is incident on the laser crystal from one end and/or at least one sidewall of the laser crystal.
12. A pulsed laser device comprising the optical amplifier according to any one of claims 1 to 11.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210774544.8A CN115084990A (en) | 2022-07-01 | 2022-07-01 | Optical amplifier and pulse laser device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210774544.8A CN115084990A (en) | 2022-07-01 | 2022-07-01 | Optical amplifier and pulse laser device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115764530A (en) * | 2022-11-10 | 2023-03-07 | 上海频准激光科技有限公司 | Optical power amplifying system and control method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115764530A (en) * | 2022-11-10 | 2023-03-07 | 上海频准激光科技有限公司 | Optical power amplifying system and control method thereof |
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