CN111736356A - A variable multi-beam MOPA laser output system and method based on optical field control - Google Patents

Abstract

The present invention provides a variable multi-beam MOPA laser output system and method based on optical field control, comprising the following steps: expanding the emitted laser beam; modulating the beam-expanded laser with a hologram to obtain a preset light Multi-beam laser with field distribution; amplify the energy of multi-beam laser to obtain high-power multi-beam laser; can flexibly control the beam and perform power amplification, and can meet a variety of laser applications. High-quality laser technology can well meet the needs of flexible manufacturing.

Description

A variable multi-beam MOPA laser output system and method based on optical field control

technical field

The invention belongs to the technical field of laser amplification and laser application, and particularly relates to a variable multi-beam MOPA laser output system and method based on optical field regulation.

Background technique

Laser processing has many characteristics such as high precision, small heat affected zone, and wide range of processing materials, and is widely used in industrial processing fields. The laser is an indispensable key component in laser processing, which determines the precision level of laser processing. In the field of laser processing, it is often necessary to process large-area group holes of various shapes and quantities. These group holes have extremely high requirements on the precision and quality of micro holes, such as aspect ratio, roundness and taper, and also require high the overall processing efficiency. Moreover, studies have shown that different light field distributions, such as Bessel light, vector light, flat top light, and Gaussian light, have different processing effects on laser processing, which can further improve the accuracy and quality of laser processing. Therefore, using multi-beam lasers with different light field distributions for laser processing can achieve high-precision, high-quality, and high-efficiency laser processing.

At present, the lasers emitted by the lasers produced at home and abroad are all single-point Gaussian distribution beams. In the laser processing process, there are often problems such as low processing efficiency, low energy utilization rate and poor adaptability. Therefore, it is often necessary to add various complexes after the laser is emitted. Optical components are used for beam shaping and laser beam splitting, and due to the limited damage threshold of optical shaping components such as spatial light modulators and digital micromirror devices, installation outside the laser will limit the energy of the beam after shaping, so it is difficult to achieve high power, For high-efficiency and high-precision laser processing, it is of great significance to study the variable multi-beam MOPA laser output system and method based on optical field control.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a variable multi-beam MOPA laser output system and method based on optical field control, which solves the defects of single laser output mode, high modulation complexity and insufficient energy utilization in current laser technology.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A variable multi-beam MOPA laser output method based on optical field regulation provided by the present invention comprises the following steps:

Expand the emitted laser beam;

The beam-expanded laser is modulated with a hologram to obtain a multi-beam laser with a preset light field distribution;

Amplify the energy of the multi-beam laser to obtain a high-power multi-beam laser.

Preferably, the laser beam emitted by the seed laser is subjected to beam expansion and hologram modulation by the optical modulation module to obtain a multi-beam laser with a preset light field distribution; then the obtained multi-beam laser is incident on the laser amplifying module, and the laser amplifying module is used for The multi-beam laser performs energy amplification to obtain a high-power multi-beam laser.

Preferably, the optical modulation module includes a λ/2 wave plate, a beam expander, a diffractive optical element and a Fourier lens, wherein the laser output from the seed laser is incident on the beam expander through the λ/2 wave plate; the The expanded beam output by the beam expander is incident on the diffractive optical element; the multi-beam laser output by the diffractive optical element is incident on the laser amplifying module through the Fourier lens.

Preferably, the laser amplifying module includes a first polarization beam splitter, a laser amplifying unit and a pump source, wherein the multi-beam laser output from the optical modulation module is incident on the first polarization beam splitter; the first polarization beam splitter The multi-beam laser output from the mirror is incident on the connected laser amplifying unit; the laser output from the pump source is incident on the laser amplifying unit.

Preferably, the laser amplifying unit includes a gain medium, a λ/4 wave plate and a second reflection mirror, wherein the multi-beam laser output from the first polarization beam splitter is incident on the second through the gain medium and the λ/4 wave plate in sequence. a reflecting mirror; the laser light output by the second reflecting mirror is reflected to the first polarization beam splitter through the λ/4 wave plate and the gain medium in turn; the laser light output by the pump source is incident on the gain medium.

Preferably, the laser amplifying unit includes an optical parametric amplifier, a λ/4 wave plate and a second polarization beam splitter, wherein the laser output from the first polarization beam splitter is incident on the optical parametric amplifier and the λ/4 wave plate in sequence. The second polarization beam splitter; the laser output from the second polarization beam splitter is reflected to the first polarization beam splitter through the λ/4 wave plate and the optical parametric amplifier in turn; the laser output from the pump source is incident on the second polarization beam beam splitter.

A variable multi-beam MOPA laser output system based on light field regulation, comprising a seed laser, an optical modulation module and a laser amplification module, wherein the seed laser is used to generate laser light and incident on the beam modulation module; modulating the received laser light to generate a multi-beam laser with a preset light field distribution; and injecting the obtained multi-beam laser light into a laser amplifying module; the laser amplifying module is used to amplify the energy of the received multi-beam laser light, Get high power multi-beam laser output.

Preferably, the optical modulation module includes a λ/2 wave plate, a beam expander, a diffractive optical element and a Fourier lens, wherein the laser output from the seed laser is incident on the beam expander through the λ/2 wave plate; the The expanded beam output by the beam expander is incident on the diffractive optical element; the multi-beam laser output by the diffractive optical element is incident on the laser amplifying module through the Fourier lens.

Preferably, the laser amplifying module includes a first polarization beam splitter, a laser amplifying unit and a pump source, wherein the multi-beam laser output from the optical modulation module is incident on the first polarization beam splitter; the first polarization beam splitter The multi-beam laser output from the mirror is incident on the connected laser amplifying unit; the laser output from the pump source is incident on the laser amplifying unit.

Preferably, the laser amplifying unit includes an optical parametric amplifier, a λ/4 wave plate and a second polarization beam splitter, wherein the laser output from the first polarization beam splitter is incident on the optical parametric amplifier and the λ/4 wave plate in sequence. The second polarization beam splitter; the laser output from the second polarization beam splitter is reflected to the first polarization beam splitter through the λ/4 wave plate and the optical parametric amplifier in turn; the laser output from the pump source is incident on the second polarization beam beam splitter.

Compared with the prior art, the beneficial effects of the present invention are:

The present invention provides a variable multi-beam MOPA laser output system and method based on light field regulation. Through the change of the hologram loaded on the diffractive optical element, the light field distribution of the laser beam can be freely regulated, so as to realize the variable multi-beam laser output. ; Using a laser amplification module to amplify the multi-beam, thereby reducing the influence of the threshold value of the beam shaping element and the diffraction loss, and realizing high-power, high-quality multi-beam laser output; The user needs to output any light field distribution, which can be directly connected to the optical element behind the system for application. The invention can flexibly control the beam and perform power amplification, can meet various laser applications, is a laser technology with high flexibility, high power and high quality, and can well meet the needs of flexible manufacturing.

Description of drawings

Fig. 1 is a system overview diagram of an embodiment of the present invention;

FIG. 2 is a system structure diagram of Embodiment 1 of an embodiment of the present invention

FIG. 3 is a system structure diagram of Embodiment 2 of an embodiment of the present invention

FIG. 4 is a system structure diagram of Embodiment 3 of an embodiment of the present invention

5 is a 5 hologram generated by a computational holographic algorithm according to an embodiment of the present invention;

Among them, 1. Seed laser, 2. Optical modulation module, 3. Laser amplification module, 4. Computer, 6. Spatial light modulator, 8. Laser shaping beam splitter, 9. Gain medium, 10. Pump source, 11 , λ/2 wave plate, 12, beam expander, 13, first reflector, 14, Fourier lens, 15, first polarizing beam splitter, 16, λ/4 wave plate, 17, second laser reflection mirror, 18, optical parametric amplifier, 19, second polarizing beam splitter.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings.

In order to solve the shortcomings of the current laser technology, such as single laser output mode, high modulation complexity and insufficient energy utilization, the present invention provides a variable multi-beam MOPA laser output system and method based on optical field control. Set the hologram of the light field distribution, use diffractive optical elements such as spatial light modulators, digital micromirror devices and laser shaping beam splitters to load the hologram to modulate the light beam, and then output a multi-beam laser that meets the preset light field distribution , and the multi-beam laser is amplified by the laser amplification module to achieve high-precision, high-quality and high-efficiency laser output.

As shown in FIG. 1 , a variable multi-beam MOPA laser output system based on optical field regulation provided by the present invention, the basic module includes a seed laser 1, an optical modulation module 2, a laser amplification module 3 and a computer 4, wherein the seed laser 1 is used to generate laser light and incident on the beam modulation module 2; the beam modulation module 2 is used to modulate the received laser light to generate a multi-beam laser with a preset light field distribution; and the obtained multi-beam laser is incident to the laser amplification module 3; the laser amplification module 3 is used to amplify the energy of the received multi-beam laser to obtain high-power multi-beam laser output; the computer 4 is respectively connected with the seed laser 1, the optical modulation module 2 and the laser amplification The module 3 is connected to control the generation of the laser, the regulation of the light field and the power of the laser amplification.

The pulse width of the seed laser 1 can be changed as required; continuous lasers, quasi-continuous lasers, nanosecond lasers, picosecond lasers and femtosecond lasers can be used as seed sources, and the energy and frequency of the seed lasers are adjustable.

The optical modulation module 2 includes a diffractive optical element, and the diffractive optical element is a spatial light modulator 6 , a digital micromirror device or a laser shaping beam splitter 8 .

The laser amplifying module 3 is mainly composed of a laser gain medium and a pump source, wherein the laser gain medium is mainly a laser crystal (such as Nd:YAG, Nd:YVO4, titanium-doped sapphire and other solid crystals), nonlinear crystals (LBO Crystal or KDP crystal, etc.) and fiber gain medium (such as Yb3+ gain fiber, Nd3+ gain fiber, etc.).

The pump source 10 is mainly semiconductor pump laser or flash lamp pump.

The pumping method of the laser amplifying module 3 can be end-pumped or side-pumped according to the beam quality and energy requirements. The end-pump is used to output multi-beam high-quality lasers, and the side-pump is used to output multi-beam high-energy lasers.

The optical modulation module 2 includes a λ/2 wave plate 11, a beam expander 12, a diffractive optical element and a Fourier lens 14, wherein the laser light output from the seed laser 1 is incident on the beam expander through the λ/2 wave plate 11. 12 ; the beam expander 12 outputs the expanded beam and enters the diffractive optical element; the multi-beam laser output from the diffractive optical element enters the laser amplifying module 3 through the Fourier lens 14 .

The diffractive optical element is a spatial light modulator 6, a digital micromirror device or a laser shaping beam splitter 8, wherein both the spatial light modulator 6 and the digital micromirror device are loaded with holograms; when the diffractive optical element is When the spatial light modulator 6 or the digital micromirror device is used, when the diffractive optical element is the spatial light modulator 8 or the digital micromirror device, the beam output by the beam expander 14 is incident on the spatial light through the first reflecting mirror 13 Modulator 8 or digital micromirror device.

The laser amplifying module 3 includes a first polarization beam splitter 15, a laser amplifying unit and a pump source 10, wherein the multi-beam laser output from the optical modulation module 2 is incident on the first polarization beam splitter 15; the first polarization beam splitter 15 The multi-beam laser output from the beam splitter 15 is incident on the connected laser amplifying unit; the laser output from the pump source 10 is incident on the laser amplifying unit.

The laser amplifying unit includes a gain medium 9, a λ/4 wave plate 16 and a second mirror 17, wherein the multi-beam laser output from the first polarizing beam splitter 15 is incident through the gain medium 9 and the λ/4 wave plate 16 in turn. to the second mirror 17; the laser output from the second mirror 17 is reflected to the first polarization beam splitter 15 through the λ/4 wave plate 16 and the gain medium 9 in turn; the laser output from the pump source 10 is incident on the Gain Medium 9.

The laser amplifying unit includes an optical parametric amplifier 18, a λ/4 wave plate 16 and a second polarization beam splitter 19, wherein the laser output from the first polarization beam splitter 15 sequentially passes through the optical parametric amplifier 18 and the λ/4 wave plate 16 is incident on the second polarization beam splitter 19; the laser output from the second polarization beam splitter 19 is reflected to the first polarization beam splitter 15 through the λ/4 wave plate 16 and the optical parametric amplifier 18 in turn; the pump source The laser light output from 10 is incident on the second polarizing beam splitter 19 .

Example 1

As shown in FIG. 2 , a variable multi-beam MOPA laser output method based on optical field regulation provided by the present invention includes the following steps:

Step 1, use the computational holography algorithm in the computer to generate a hologram of the specified target light field distribution, as shown in Figure 5, and load the hologram on the spatial light modulator 6 or the digital micromirror device;

The computational holography algorithm shown in step 1 is an iterative Fourier transform algorithm, such as the GS algorithm, the GSW algorithm, the ORA algorithm, and the MRAF algorithm.

In step 1, the spatial light modulator 6 loaded with the hologram can control the amplitude, phase and polarization state of the light beam; the digital micromirror device loaded with the hologram can control the amplitude and phase of the light beam.

Step 2, the laser beam emitted by the seed laser 1 is incident on the beam expander 12 after passing through the λ/2 wave plate 11 for beam expansion, and the beam diameter after beam expansion is not larger than the spatial light modulator 6 or the working panel of the digital micromirror device. Then, the expanded beam is incident on the spatial light modulator 6 or the digital micromirror device at an appropriate angle, and the incident laser beam can generate a preset light field distribution after being modulated by the hologram. The hologram on the light modulator 6 or the digital micromirror device can realize other arbitrary target light field distribution;

Step 3, the modulated multi-beam is incident into the gain medium 9, the first polarizing beam splitter 15 and the second mirror 17 act as resonators, and the pump source 10 is used to generate population inversion or output with the seed laser 1 The phase matching of the laser is completed, the λ/4 wave plate 16 is used to change the polarization state of the laser, and the multi-beam is continuously folded in the polarization beam splitter 15 and the second reflecting mirror 17, thereby producing a high-quality, high-power multi-beam laser.

Example 2

As shown in FIG. 3 , a method for outputting a variable multi-beam MOPA laser based on optical field control provided by the present invention includes the following steps:

Step 1, use the computational holography algorithm to generate a hologram of the specified target light field distribution, as shown in Figure 5, use the laser direct writing method to process the hologram into the corresponding laser beam splitter 8, different holograms can be processed into different targets The laser shaping beam splitter 8 of the light field distribution, the computational holography algorithm of this embodiment is generated by the computer 4;

Step 2, the laser beam emitted by the seed laser 1 is incident on the beam expander 12 for beam expansion, the beam diameter after beam expansion is not greater than the size of the laser shaping beam splitter 8, and then the beam after beam expansion is incident on the laser beam at an appropriate angle Shaping beam splitter 8, the incident laser beam can generate a preset light field distribution after being modulated by the laser shaping beam splitter 8;

Step 3, the modulated multi-beam is incident into the gain medium 9, the first polarizing beam splitter 15 and the second mirror 17 act as resonators, and the pump source 10 is used to generate population inversion or output with the seed laser 1 The laser is phase-matched, the λ/4 wave plate 16 is used to change the polarization state of the laser, and the multi-beams are continuously folded in the first polarizing beam splitter 15 and the second reflecting mirror 17, thereby generating high-quality, high-power multi-beams laser.

Example 3

As shown in FIG. 4 , a variable multi-beam MOPA laser output method based on optical field regulation provided by the present invention includes the following steps:

Step 1, use the computational holography algorithm to generate a hologram of the specified target light field distribution, as shown in Figure 5, and load the hologram on the spatial light modulator 6 or the digital micromirror device; The light modulator 6 or the digital micromirror device is controlled by the computer 4;

Step 2, the laser beam emitted by the seed laser 1 is incident on the beam expander 12 for beam expansion, and the beam diameter after beam expansion is not larger than the size of the working panel of the spatial light modulator 6 or the digital micromirror device, and then the expanded beam is The light beam is incident on the spatial light modulator 6 or the digital micromirror device at an appropriate angle. The incident laser beam can be modulated by the hologram to generate a preset light field distribution. By changing the load on the spatial light modulator 6 or the digital micromirror device On the hologram, other target light field distributions can be realized;

Step 3, the modulated multi-beam is incident on the optical parametric amplifier 18, the first polarizing beam splitter 15 and the second polarizing beam splitter 19 act as resonators, and the pump source 10 and the seed laser are generated in the optical parametric amplifier 18 Phase matching is used for power amplification, λ/4 wave plate 16 is used to change the polarization state of the laser, and multiple beams are continuously folded in the first polarization beam splitter 15 and the second polarization beam splitter 19, thereby generating high-quality, high-power multi-beam laser.

Although the seed laser 1, the optical modulation module 2, the laser amplification module 3, the computer 4, the spatial light modulator 6, the laser shaping beam splitter 8, the gain medium 9, the pump source 10, the λ/ 2 wave plate 11, beam expander 12, first reflecting mirror 13, Fourier lens 14, first polarizing beam splitter 15, λ/4 wave plate 16, second laser reflecting mirror 17, optical parametric amplifier 18, Two polarization beamsplitters 19, but does not exclude the possibility of using other terms, which are only used to describe the nature of the present invention more conveniently, and it is consistent with the spirit of the present invention to interpret them as any kind of additional limitation violated.

It should be understood that the parts not described in detail in this specification belong to the prior art.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, All simplifications should be equivalent substitutions, which are all included in the protection scope of the present invention.

Claims (10)

1. a variable multi-beam MOPA laser output method based on light field regulation, is characterized in that, comprises the following steps: Expand the emitted laser beam; The beam-expanded laser is modulated with a hologram to obtain a multi-beam laser with a preset light field distribution; Amplify the energy of the multi-beam laser to obtain a high-power multi-beam laser. 2. a kind of variable multi-beam MOPA laser output method based on light field regulation according to claim 1, is characterized in that, by optical modulation module (2), the laser beam that seed laser (1) sends is carried out beam expansion, holography Then, the obtained multi-beam laser is incident on the laser amplifying module (3), and the energy of the multi-beam laser is amplified by the laser amplifying module (3) to obtain a high-power multi-beam laser. beam laser. 3. a kind of variable multi-beam MOPA laser output method based on light field regulation according to claim 2, is characterized in that, described optical modulation module (2) is to comprise λ/2 wave plate (11), beam expander a mirror (12), a diffractive optical element and a Fourier lens (14), wherein the laser light output from the seed laser (1) is incident on a beam expander (12) through a λ/2 wave plate (11); the beam expander (12) The beams after beam expansion are output and are incident on the diffractive optical element; the multi-beam lasers output by the diffractive optical element are incident on the laser amplifying module (3) through the Fourier lens (14). 4. a kind of variable multi-beam MOPA laser output method based on light field regulation according to claim 2, is characterized in that, described laser amplifying module (3) comprises the first polarizing beam splitter (15), laser amplifying Unit and pump source (10), wherein the multi-beam laser output from the optical modulation module (2) is incident on a first polarization beam splitter (15); the multi-beam laser output from the first polarization beam splitter (15) incident on the connected laser amplifying unit; the laser output from the pump source (10) is incident on the laser amplifying unit. 5. a kind of variable multi-beam MOPA laser output method based on light field regulation according to claim 4, is characterized in that, laser amplifying unit comprises gain medium (9), λ/4 wave plate (16) and second a reflector (17), wherein the multi-beam laser light output by the first polarization beam splitter (15) is incident on the second reflector (17) through the gain medium (9) and the λ/4 wave plate (16) in sequence; The laser light output by the second reflection mirror (17) is reflected to the first polarization beam splitter (15) through the λ/4 wave plate (16) and the gain medium (9) in turn; the laser light output by the pump source (10) The laser light is incident on the gain medium (9). 6. a kind of variable multi-beam MOPA laser output method based on optical field regulation according to claim 4, is characterized in that, laser amplifying unit comprises optical parametric amplifier (18), λ/4 wave plate (16) and the first A two-polarization beam splitter (19), wherein the laser light output by the first polarization beam splitter (15) is incident on the second polarization beam splitter through an optical parametric amplifier (18) and a λ/4 wave plate (16) in sequence (19); the laser light output by the second polarization beam splitter (19) is reflected to the first polarization beam splitter (15) through a λ/4 wave plate (16) and an optical parametric amplifier (18) in turn; the pumping The laser light output by the source (10) is incident on the second polarizing beam splitter (19). 7. A variable multi-beam MOPA laser output system based on light field regulation, characterized in that it comprises a seed laser (1), an optical modulation module (2) and a laser amplification module (3), wherein the seed laser (1) for generating laser light and incident on the beam modulation module (2); the beam modulation module (2) is used for modulating the received laser light to generate a multi-beam laser with a preset light field distribution; and the obtained multi-beam laser Incident to the laser amplifying module (3); the laser amplifying module (3) is used to amplify the energy of the received multi-beam laser to obtain a high-power multi-beam laser output. 8. A variable multi-beam MOPA laser output system based on optical field regulation according to claim 7, wherein the optical modulation module (2) comprises a λ/2 wave plate (11), a beam expander a mirror (12), a diffractive optical element and a Fourier lens (14), wherein the laser light output from the seed laser (1) is incident on a beam expander (12) through a λ/2 wave plate (11); the beam expander (12) The beams after beam expansion are output and are incident on the diffractive optical element; the multi-beam lasers output by the diffractive optical element are incident on the laser amplifying module (3) through the Fourier lens (14). 9. A variable multi-beam MOPA laser output system based on optical field regulation according to claim 7, wherein the laser amplification module (3) comprises a first polarization beam splitter (15), a laser amplification A unit and a pump source (10), wherein the multi-beam laser output from the optical modulation module (2) is incident on a first polarization beam splitter (15); the multi-beam laser output from the first polarization beam splitter (15) Incident to the connected laser amplifying unit; the laser output from the pump source (10) is incident to the laser amplifying unit. 10. A variable multi-beam MOPA laser output system based on optical field regulation according to claim 9, wherein the laser amplifying unit comprises an optical parametric amplifier (18), a λ/4 wave plate (16) and a A two-polarization beam splitter (19), wherein the laser light output by the first polarization beam splitter (15) is incident on the second polarization beam splitter through an optical parametric amplifier (18) and a λ/4 wave plate (16) in sequence (19); the laser light output by the second polarization beam splitter (19) is reflected to the first polarization beam splitter (15) through a λ/4 wave plate (16) and an optical parametric amplifier (18) in turn; the pumping The laser light output by the source (10) is incident on the second polarizing beam splitter (19).

Images