CN110109259A - The beam merging apparatus of semiconductor laser high light beam quality high-power output - Google Patents

Abstract

The invention discloses a semiconductor laser beam combining device with high beam quality and high power output, comprising: N beam combining subsystems and a grating pair for combining sub-beams output by the N beam combining subsystems; the beam combining subsystem includes The semiconductor laser stack and the fast axis collimating mirror, the slow axis collimating mirror, the conversion lens, the first grating and the output mirror arranged in sequence along the light path direction of the outgoing light of the semiconductor laser stack; the grating pair includes the second grating arranged in parallel. grating and third grating. In the present invention, the external cavity and the back cavity surface of the semiconductor laser are used to form an external cavity semiconductor laser, so that different beam combining units are locked at different wavelengths, and then the laser beams emitted by each semiconductor laser array are overlapped in space by using the dispersion effect of the grating. The output into one beam can maintain a good level of beam quality while increasing the output power. In this way, the beam quality after beam combining has been greatly improved, and the beam combining output with high power and high beam quality has been realized.

Description

Beam combining device with high beam quality and high power output of semiconductor laser

technical field

The invention relates to the technical field of high-power semiconductor laser applications, in particular to a beam combining device with high beam quality and high power output of semiconductor lasers.

Background technique

Semiconductor laser is a kind of electro-optical conversion device with rapid development and wide scientific penetration in the past fifty years. It has important applications in industrial processing, military defense, optical communication and other fields. However, due to the limitations of its waveguide structure and device packaging technology, the beam quality in the direction of the fast and slow axes is quite different. For example, for ordinary cm bar bars, the quality of the beam in the direction of the slow axis is thousands of times that of the direction of the fast axis. resulting in poor output beam quality. Although the stack structure can achieve higher power output, limited by the small cross-sectional area of the water channel in the microchannel heat sink and the water pressure drop, the number of laser layers in the laser stack cannot be superimposed infinitely, generally not exceeding 50 layers, thus limiting This makes it difficult to be directly applied as a hundred-watt or kilowatt-level light source. Therefore, how to simultaneously obtain high power and high beam quality semiconductor laser output has become a major technical bottleneck in the world.

Contents of the invention

The technical problem to be solved by the present invention is to provide a semiconductor laser beam combiner with high beam quality and high power output for the above-mentioned deficiencies in the prior art.

In order to solve the above technical problems, the technical solution adopted by the present invention is: a semiconductor laser beam combining device with high beam quality and high power output, including: N beam combining subsystems and a subsystem for outputting the N beam combining subsystems A pair of gratings for beam combining;

The beam combining subsystem includes a semiconductor laser stack and a fast-axis collimator, a slow-axis collimator, a conversion lens, a first grating, and an output mirror that are sequentially arranged along the optical path direction of the outgoing light of the semiconductor laser stack;

The pair of gratings includes a second grating and a third grating arranged parallel to each other;

The light emitted by the semiconductor laser stack passes through the fast-axis collimator and the slow-axis collimator in turn, and then is converted into different incident angles by the conversion lens and projected onto the first grating. After being diffracted by the first grating, the outgoing light is combined at the same diffraction angle to form a sub-beam, and then output to the second grating through the output mirror; the sub-beams output by the N beam combining subsystems are all incident on the The second grating is incident on the same position of the third grating to generate overlap, and after being diffracted by the third grating, the beams are combined and output at the same exit angle.

Preferably, the centers of the fast-axis collimating mirror, the slow-axis collimating mirror, the transformation lens and the first grating are all located on the same straight line as the center of the semiconductor laser stack.

Preferably, the output mirror is arranged perpendicular to the -1st order diffraction direction of the first grating.

Preferably, the emitted light from different stacks of the semiconductor laser stack is diffracted by the first grating and combined at the same angle as the -1st order diffraction direction of the first grating to form a sub-beam, and then passed through the first grating The above output mirrors the output.

Preferably, the output mirror reflects part of the incident sub-beams back to the semiconductor laser stack according to the original path, so as to lock the output wavelength of the semiconductor laser stack.

Preferably, the power of the semiconductor laser stack is adjustable, and the wavelength range of the emitted light is 400nm-1550nm.

Preferably, the beam combining device includes two beam combining subsystems, and the sub-beams output by the two beam combining subsystems are directly incident on the second grating.

Preferably, the beam combining device further includes N mirrors, configured to reflect the output sub-beams of each of the beam combining subsystems to the second grating.

The beneficial effects of the present invention are: the semiconductor laser beam combining device with high beam quality and high power output of the present invention first uses the external cavity and the back cavity surface of the semiconductor laser to form an external cavity semiconductor laser, so that different beam combining units can be locked at different wavelengths, Using the dispersion effect of the grating, the laser beams emitted by each semiconductor laser stack are superimposed into one output beam in space, which can maintain a good beam quality level while increasing the output power, so that the beam quality after beam combining has been greatly improved. Improvement, realizing the combined output of high power and high beam quality.

Description of drawings

Fig. 1 is the structural representation of the beam combination device of high beam quality and high power output of semiconductor laser in embodiment 1 of the present invention;

FIG. 2 is a schematic structural diagram of a beam combining device with high beam quality and high power output of semiconductor lasers in Embodiment 1 of the present invention.

Explanation of reference signs:

1—semiconductor laser stack; 2—fast axis collimating mirror; 3—slow axis collimating mirror; 4—transformation lens; 5—first grating; 6—output mirror; 7—second grating; 8—third grating 9—beam combining laser; 10—sub-beam; 11—mirror; 12—beam combining laser.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments, so that those skilled in the art can implement it with reference to the description.

It should be understood that terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

As shown in Figure 1-2, a semiconductor laser beam combining device with high beam quality and high power output in this embodiment includes N beam combining subsystems and a beam combining sub-beams output by the N beam combining subsystems grating pair;

The beam combining subsystem includes a semiconductor laser stack 1 and a fast-axis collimating mirror 2, a slow-axis collimating mirror 3, a conversion lens 4, a first grating 5, and an output mirror that are sequentially arranged along the optical path direction of the outgoing light of the semiconductor laser stack 1. 6;

The grating pair includes a second grating 7 and a third grating 8 arranged parallel to each other;

The light emitted by the semiconductor laser stack 1 passes through the fast-axis collimating mirror 2 and the slow-axis collimating mirror 3 in turn, and is converted into different incident angles by the conversion lens 4 and projected onto the first grating 5. The outgoing light of different stacks passes through After the first grating 5 is diffracted, the sub-beams are combined at the same diffraction angle to form sub-beams, and then output to the second grating 7 through the output mirror 6; the output sub-beams of the N beam combining subsystems are all incident on the second grating 7, and then incident on the second grating 7. The overlapping occurs at the same position of the third grating 8 , and the beams are combined and output at the same output angle after being diffracted by the third grating 8 .

In the present invention, the grating-external cavity spectral beam combination technology is used to shape the laser output from the semiconductor array with poor beam quality, so as to achieve high beam quality output. Then N (N ≥ 2) shaped stacks are combined using common aperture technology. Since the double grating structure compensates for dispersion, the beam combining can maintain high beam quality and achieve high power output at the same time. In this way, the beam quality after beam combining has been greatly improved, thus achieving high beam quality output.

Wherein, the power of the semiconductor laser stack 1 is adjustable, and the wavelength range of the light emitted by it is 400nm-1550nm. The centers of the fast-axis collimating mirror 2, the slow-axis collimating mirror 3, the transformation lens 4 and the first grating 5 are all located on the same straight line as the center of the semiconductor laser stack. The fast-axis collimating mirror 2 and the slow-axis collimating mirror 3 respectively compress the divergence angles of the fast and slow axes to the milliradian level.

Wherein, the output mirror 6 is arranged perpendicular to the -1st order diffraction direction of the first grating 5 . The outgoing light from different stacks of the semiconductor laser stack 1 is diffracted by the first grating 5 and combined at the same angle as the -1st order diffraction direction of the first grating 5 to form sub-beams, and then output through the output mirror 6 . Due to the partial feedback effect of the output mirror 6, the output mirror 6 reflects part of the incident sub-beam according to the original path (passing through the first grating 5, the conversion lens 4, the slow axis collimator mirror 3, and the fast axis collimator mirror 2) back to the semiconductor The laser stack 1 is used to lock the output wavelength of the semiconductor laser stack 1 (even if different beam combining units are locked at different wavelengths). The rear end face of the stack and the output mirror 6 in the -1st order diffraction direction form an external resonant cavity, and the beam injected by feedback forms an oscillation in the external resonant cavity. Due to the effect of gain competition, different beam combining units operate at different wavelengths, and The output sub-beams will be spatially superimposed on the grating pair along the central unit, that is, power superposition. The output beams of each beam combining subsystem have the same beam quality, and the spatial brightness of the combined output beam will increase significantly compared with that before the beam combining, realizing superposition Improvement of the array output beam quality.

Due to the small cross-sectional area of the water channel in the heat sink and the water pressure drop, the number of layers of the laser stack cannot be increased indefinitely (generally less than 50 layers), so the increase in output power is limited. For this reason, the present invention uses double gratings to combine the sub-beams output by N subsystems with the same parameters (N (N≥2) subsystems can be selected according to actual needs). The double-grating beam combining technology not only reduces the laser line width, The control requirements of the phase and other aspects can also maintain a good level of beam quality while increasing the output power, thereby realizing the high-power and high-beam quality laser output of the entire system.

Specific examples are provided below to further illustrate the present invention.

Example 1

With reference to Fig. 1, in the present embodiment, the beam combining device of high beam quality and high power output of semiconductor lasers includes 2 beam combining subsystems: beam combining subsystem I and beam combining subsystem II with the same structure, and the output sub-beams of the 2 beam combining subsystems are directly incident on the second grating 7. The sub-beams output by the output mirror 6 of the beam combining subsystem I and the sub-beams output by the output mirror 6 of the beam combining subsystem II are both directly incident on the second grating 7 in the grating pair. In order to obtain higher diffraction efficiency of the sub-beam, the incident angle of the sub-beam should be as close as possible to the Littrow angle of the second grating 7 at the blaze wavelength. The second grating 7 and the third grating 8 are placed in parallel, and the third grating 8 will effectively compensate the dispersion generated by the second grating 7 . The dispersion of the second grating 7 makes the first-order diffracted beams of sub-beams of different wavelengths incident on the same position of the third grating 8 with identical parameters to overlap, and after diffraction by the third grating 8, the beams of sub-beams of different wavelengths are combined The final output beams have the same exit angle, and the combined laser beam 9 is obtained, which finally realizes the common-aperture spectral synthesis output of two sub-beams with different wavelengths, which greatly improves the total output power of the system. The dispersion compensation effect of the third grating 8 on the second grating 7 ensures that the combined beams of the system can obtain a higher quality level, thus realizing the beam combining output of the whole system with high power and high beam quality.

Since the power of stacked arrays is limited by the number of stacked layers, the power of a single stacked array is difficult to meet high-power applications. In order to increase the power, the subsystem II with the same structure as the subsystem I is combined with double gratings to achieve power superposition, thereby increasing the total output power. This solution not only reduces the control requirements on the laser linewidth and phase used for beam combining, but also can maintain a good beam quality level while increasing the output power.

Example 2

Referring to Fig. 2, in the present embodiment, the number N of beam combining subsystems is greater than 2 (the structures of the N beam combining subsystems are all the same, and are also the same as those in the above-mentioned embodiments, as shown in the oval dotted line box), and the semiconductor laser The beam combining device with high beam quality and high power output also includes N reflectors 11, and the N mirrors 11 correspond to the N beam combining subsystems one by one, and are used to reflect the output sub-beam 10 of each beam combining subsystem to the first Two gratings7. That is, the sub-beams 10 output by each beam combining subsystem are reflected to the second grating 7 by a mirror 11, and the dispersion of the second grating 7 makes the first-order diffracted beams of the sub-beams 10 of different wavelengths incident on the third third grating with the same parameters. Overlap occurs at the same position of the grating 8, and after diffraction by the third grating 8, the combined output beams of different wavelength sub-beams 10 have the same output angle, and the combined beam laser 12 is obtained, and finally N channels of different wavelength sub-beams are realized. The common-aperture spectral synthesis output of the beam 10 greatly improves the total output power of the system.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details without departing from the general concept defined by the claims and their equivalents.

Claims (8)

1. A beam combining device with high beam quality and high power output of a semiconductor laser, comprising: N beam combining subsystems and a grating pair for combining the sub-beams output by the N beam combining subsystems; The beam combining subsystem includes a semiconductor laser stack and a fast-axis collimator, a slow-axis collimator, a conversion lens, a first grating, and an output mirror that are sequentially arranged along the optical path direction of the outgoing light of the semiconductor laser stack; The pair of gratings includes a second grating and a third grating arranged parallel to each other; The light emitted by the semiconductor laser stack passes through the fast-axis collimator and the slow-axis collimator in turn, and then is converted into different incident angles by the conversion lens and projected onto the first grating. After being diffracted by the first grating, the outgoing light is combined at the same diffraction angle to form a sub-beam, and then output to the second grating through the output mirror; the sub-beams output by the N beam combining subsystems are all incident on the The second grating is incident on the same position of the third grating to generate overlap, and after being diffracted by the third grating, the beams are combined and output at the same exit angle. 2. the beam combiner of semiconductor laser high beam quality high power output according to claim 1, is characterized in that, the center of described fast axis collimating mirror, slow axis collimating mirror, conversion lens, the first grating is all with The centers of the semiconductor laser stacks are located on the same straight line. 3. The semiconductor laser beam combiner with high beam quality and high power output according to claim 2, characterized in that the output mirror is arranged perpendicular to the -1st order diffraction direction of the first grating. 4. The beam combining device of high beam quality and high power output of semiconductor laser according to claim 3, characterized in that, the outgoing light of different stacks of the semiconductor laser stack is diffracted by the first grating to be compatible with the The -1 order diffraction directions of the first grating are combined at the same angle to form sub-beams, which are then output through the output mirror. 5. The beam combining device of high beam quality and high power output of semiconductor lasers according to claim 4, wherein the output mirror reflects part of the incident sub-beams back to the stack of semiconductor lasers according to the original path, so that The locking of the output wavelength of the semiconductor laser stack is realized. 6 . The semiconductor laser beam combiner with high beam quality and high power output according to claim 5 , wherein the power of the semiconductor laser stack is adjustable, and the wavelength range of the light emitted by it is 400nm-1550nm. 7. The beam combining device of high beam quality and high power output of semiconductor laser according to any one of claims 1-6, characterized in that, the beam combining device comprises 2 beam combining subsystems, and the output subsystems of the 2 beam combining subsystems All light beams are directly incident on the second grating. 8. The beam combining device of high beam quality and high power output of semiconductor lasers according to any one of claims 1-6, characterized in that, the beam combining device also includes N reflectors for combining each of the combined beams The output sub-beams of the beam subsystem are reflected to the second grating.