Miniaturized laser coherent beam combining device based on polarization grating

Abstract

The utility model relates to a polarization grating-based miniaturized coherent laser beam combining device, which is characterized in that an MOPA (Metal Organic Power Amplifier) amplifying device, a light beam collimating device, a polarization adjusting device and a polarization coherent combining device are sequentially arranged on light paths of two paths of laser sub-beams, and the two paths of laser sub-beams are laser sub-beams with high coherence and complete polarization state; a beam splitting device is arranged on a light path of the coherent combined light beam, and a photoelectric detection device is arranged on one beam splitting light path of the beam splitting device; the polarization coherent combination device comprises a conversion mirror and a polarization grating, the polarization grating is located at the focus of the conversion mirror, the two MOPA amplification devices are symmetrically arranged, the polarization grating is located on the symmetry axis of the two MOPA amplification devices, and the near-field coherent combination system can solve the technical problems that in the prior art, a near-field coherent combination system is large in size and complex in light path.

Description

Technical Field

[0001] The utility model belongs to the technical field of semiconductor lasers, and particularly relates to a miniaturized laser coherent beam combining device based on a polarization grating. Background Art

[0002] When the potential for increasing the power of a single laser sub-beam is limited, laser synthesis technology can superimpose the powers of multiple laser sub-beams, which is an effective method for realizing a high-power and high-brightness laser light source. Among them, coherent beam combining technology uses the method of constructive interference to superimpose the powers of multiple highly coherent and highly polarized laser sub-beams, and has unique advantages such as not sacrificing the line width of the sub-beams, having strong scalability, and a low beam quality degradation rate in a group of laser synthesis technologies, and has been significantly developed in recent years. In terms of the beam combining method, coherent beam combining has two forms: near-field coherent beam combining and far-field coherent beam combining. Among them, compared with far-field coherent beam combining, near-field coherent beam combining has lower requirements for the accuracy of the array itself, no requirements for the transmission distance, and no side lobes in the far-field light spot, which is more conducive to the realization of a high-brightness laser integrated light source. However, the near-field coherent beam combining system is large in volume and the optical field is relatively complex. Even if the near-field coherent beam combining device has developed to the limit, it is still difficult to solve the problems of system enlargement and optical path complexity.

[0003] Therefore, there is an urgent need for a miniaturized laser coherent beam combining device. Summary of the Utility Model

[0004] In view of the various deficiencies of the prior art, a miniaturized laser coherent beam combining device based on a polarization grating is proposed to solve the technical problems of large volume and complex optical path of the near-field coherent beam combining system in the prior art.

[0005] To achieve the above object, the utility model provides the following technical solutions:

[0006] A miniaturized laser coherent beam combining device based on a polarization grating is provided, in which a MOPA amplification device, a beam collimation device, an adjustment polarization device, and a polarization coherent beam combining device are sequentially arranged on the optical paths of two laser sub-beams. The two laser sub-beams are laser sub-beams with high coherence and complete polarization states. A beam splitting device is arranged on the optical path of the coherent combined beam, and a photoelectric detection device is arranged on one of the split optical paths of the beam splitting device;

[0007] The polarization coherent beam combining device includes a transformation mirror and a polarization grating. The polarization grating is located at the focal point of the transformation mirror, and two MOPA amplification devices are symmetrically arranged. The polarization grating is located on the symmetry axis of the two MOPA amplification devices.

[0008] This technical solution is further configured such that the two laser sub-beams are lasers with single transverse mode, single longitudinal mode, and 100% polarization degree, and the wavelength is matched with the chip used in the MOPA amplification device.

[0009] This technical solution is further configured such that the two laser sub-beams are fiber lasers, semiconductor lasers, solid-state lasers, or chemical lasers.

[0010] This technical solution is further configured such that a fiber collimation device and a coupling device are sequentially arranged on the optical path before the MOPA amplification device. The two laser sub-beams output parallel beams after passing through the beam collimation device, and the parallel beams output circularly polarized light with different rotation directions of the optical vector after passing through the polarization adjustment device.

[0011] This technical solution is further configured such that a phase controller is also arranged between the MOPA amplification device and the photoelectric detection device, and the MOPA amplification device and the photoelectric detection device are respectively communicatively connected to the phase controller.

[0012] This technical solution is further configured such that the chip used in the MOPA amplification device has an on-chip phase modulation function for semiconductor chips, and its modulation range reaches more than 2π.

[0013] This technical solution is further configured such that the photoelectric detection device includes a photodetector and a signal sampling device, and the signal sampling device is an oscilloscope or a data acquisition card.

[0014] This technical solution is further configured such that the fiber collimation device is a fiber collimator, the coupling device is a coupling lens, the beam collimation device is a collimating lens, the polarization adjustment device is a polarization controller, the transformation mirror is a focusing lens, and the beam splitting device is a beam splitter.

[0015] The beneficial effects of the present utility model are:

[0016] By setting a polarization grating to realize coherent beam combination of laser sub-beams, the optical path is simple, which is beneficial to the miniaturization of the laser coherent beam combination device; combining the semiconductor laser MOPA amplification technology with the polarization grating makes full use of the advantage of the miniaturization of semiconductor lasers; only one transformation mirror and one polarization grating are needed to achieve high-efficiency coherent synthesis of two-way MOPA amplification. Description of the Drawings

[0017] Figure 1 is a schematic diagram of the miniaturized laser coherent beam combination device based on a polarization grating in the embodiment of the present utility model;

[0018] Figure 2 is a graph of the amplified coherent synthesis output of sub-beam 1 and sub-beam 2 in the embodiment of the present utility model.

[0019] In the attached drawings: 1. Fiber collimation device; 2. Coupling device; 3. MOPA amplification device; 4. Beam collimation device; 5. Polarization adjustment device; 6. Transformation mirror; 7. Polarization grating; 8. Photoelectric detection device; 9. Phase controller; 10. Beam splitting device. Detailed implementation mode

[0020] In order to enable those skilled in the art to better understand the technical solution of the present utility model, the technical solution of the present utility model will be clearly and completely described below in conjunction with the attached drawings of the present utility model. Based on the embodiments in this application, other similar embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of this application. In addition, the directional terms mentioned in the following embodiments, such as "upper", "lower", "left", "right", etc., are only with reference to the directions in the attached drawings. Therefore, the directional terms used are for illustration rather than limitation of the present invention.

[0021] The present utility model will be further described below in conjunction with the attached drawings and preferred embodiments.

[0022] According to an embodiment of the present utility model, a miniaturized laser coherent beam combining device based on a polarization grating is provided. Please refer to Figure 1 , on the optical paths of two laser sub-beams, an MOPA amplification device 3, a beam collimation device 4, a polarization adjustment device 5, and a polarization coherent combination device are sequentially arranged. The two laser sub-beams are laser sub-beams with high coherence and complete polarization states. A beam splitting device 10 is arranged on the optical path of the coherent combined beam. An optoelectronic detection device 8 is arranged on one of the split optical paths of the beam splitting device 10;

[0023] The polarization coherent combination device includes a transformation mirror 6 and a polarization grating 7. The polarization grating 7 is located at the focal point of the transformation mirror 6. Two MOPA amplification devices 3 are symmetrically arranged. The polarization grating 7 is located on the symmetry axis of the two MOPA amplification devices 3.

[0024] It should be noted that by setting the polarization grating 7, the coherent beam combination of laser sub-beams is realized, the optical path is simple, which is beneficial to the miniaturization of the laser coherent beam combining device; the semiconductor laser MOPA amplification technology is combined with the polarization grating 7, making full use of the advantage of the semiconductor laser being miniaturizable; only one transformation mirror 6 and one polarization grating 7 are required to achieve high-efficiency coherent synthesis of two-way MOPA amplification.

[0025] In the miniaturized laser coherent beam combining device based on a polarization grating in this embodiment, please refer to Figure 1 , the two laser sub-beams are semiconductor lasers with single transverse mode, single longitudinal mode, and 100% polarization degree, and the wavelength matches the chip used in the MOPA amplification device 3. The two laser sub-beams are fiber lasers, semiconductor lasers, solid lasers, or chemical lasers.

[0026] It should be noted that the two laser sub-beams are sub-beam 1 and sub-beam 2 respectively. Sub-beam 1 and sub-beam 2 are not limited to semiconductor lasers only. Lasers with high coherence and complete polarization states can be fiber lasers, solid-state lasers, and chemical lasers with single transverse mode, single longitudinal mode, and a polarization degree of 100%. All of them can achieve miniaturization by using this structure.

[0027] In the miniaturized laser coherent beam combining device based on a polarization grating in this embodiment, please refer to Figure 1 , a fiber collimating device 1 and a coupling device 2 are sequentially arranged on the optical path before the MOPA amplification device 3. The two laser sub-beams output parallel beams after passing through the beam collimating device 4, and the parallel beams output circularly polarized light with different rotation directions of the optical vector after passing through the polarization adjustment device 5.

[0028] It should be noted that two polarization-maintaining laser sub-beams with high coherence pass through the fiber collimating device 1, the coupling device 2, the MOPA amplification device 3, the beam collimating device 4, the polarization adjustment device 5, the transformation mirror 6, and the polarization grating 7 respectively. The beam collimating device 4 evolves the beam amplified by the MOPA amplification device 3 into a parallel beam; the polarization adjustment device 5 evolves the parallel beam into left-handed circularly polarized light and right-handed circularly polarized light.

[0029] In the miniaturized laser coherent beam combining device based on a polarization grating in this embodiment, please refer to Figure 1 , a phase controller 9 is also arranged between the MOPA amplification device 3 and the photoelectric detection device 8, and the MOPA amplification device 3 and the photoelectric detection device 8 are respectively communicatively connected to the phase controller 9.

[0030] Specifically, the chip adopted by the MOPA amplification device 3 has an on-chip phase modulation function of a semiconductor chip, and its modulation range reaches more than 2π.

[0031] It should be noted that through the on-chip phase modulation technology and the active phase control algorithm, the miniaturized high-brightness laser coherent beam combining is finally realized, which well promotes the development of the high-brightness and high-coherence light source system.

[0032] In the miniaturized laser coherent beam combining device based on a polarization grating in this embodiment, please refer to Figure 1 , the photoelectric detection device 8 includes a photodetector and a signal sampling device, and the signal sampling device is an oscilloscope or a data acquisition card.

[0033] It should be noted that the coherently combined beam output by the polarization grating 7 is split by the beam splitting device 10. One split beam passes through the photoelectric detection device 8 and is fed back to the phase controller 9. Miniaturized laser coherent beam combination is completed through on-chip phase modulation technology. Specifically, the phases of the laser sub-beams are real-time regulated through a phase servo control algorithm, and the regulation results are obtained through the photoelectric detection device 8, thereby realizing a closed loop. The other split beam is used as the output of the coherently combined laser. By adjusting the transformation mirror 6 and the polarization grating 7, when the optical voltage signal collected by the photoelectric detection device 8 reaches the instantaneous maximum value, the coherent combination efficiency of the left-handed circularly polarized light and the right-handed circularly polarized light is the highest.

[0034] Preferably, the optical fiber collimation device 1 is an optical fiber collimator, the coupling device 2 is a coupling lens, the beam collimation device 4 is a collimation lens, the polarization adjustment device 5 is a polarization controller, which can be an optical fiber polarization controller or a combined structure of a λ / 2 glass sheet and a λ / 4 glass sheet. The transformation mirror 6 is a focusing mirror, the beam splitting device 10 is a beam splitter. The optical voltage value of sub-beam 1 is 0.873V, and the optical voltage value of sub-beam 2 is 0.894V. For the amplified coherent combination output curves of sub-beam 1 and sub-beam 2, please refer to Figure 2 , and its combined optical voltage value is 1.661V, and the combination efficiency is 94%.

[0035] The above has described the present invention in detail. The above description is only a preferred embodiment of the present invention and cannot limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the scope of this application should still fall within the scope covered by the present invention.

Claims

1. A miniaturized laser coherent beam combining device based on a polarization grating, characterized in that, An MOPA amplification device, a beam collimation device, an adjustment polarization device, and a polarization coherent combination device are sequentially arranged on the optical paths of two laser sub-beams. The two laser sub-beams are laser sub-beams with high coherence and complete polarization states. A beam splitting device is arranged on the optical path of the coherent combined beam, and a photoelectric detection device is arranged on one of the split optical paths of the beam splitting device. The polarization coherent combination device includes a transformation mirror and a polarization grating. The polarization grating is located at the focal point of the transformation mirror. Two MOPA amplification devices are symmetrically arranged, and the polarization grating is located on the symmetry axis of the two MOPA amplification devices.

2. The miniaturized laser coherent beam combining device based on a polarization grating according to claim 1, wherein The two laser sub-beams are lasers with a single transverse mode, a single longitudinal mode, and a polarization degree of 100%, and the wavelength matches the chip used in the MOPA amplification device.

3. The miniaturized laser coherent beam combining device based on a polarization grating according to claim 2, characterized in that, The two laser sub-beams are fiber lasers, semiconductor lasers, solid lasers, or chemical lasers.

4. The miniaturized laser coherent beam combining device based on a polarization grating according to claim 1, characterized in that, A fiber collimation device and a coupling device are also sequentially arranged on the optical path before the MOPA amplification device. The two laser sub-beams output parallel beams after passing through the beam collimation device, and the parallel beams output circularly polarized light with different rotation directions of the optical vector after passing through the adjustment polarization device.

5. The miniaturized laser coherent beam combining device based on a polarization grating according to claim 4, characterized in that, A phase controller is also arranged between the MOPA amplification device and the photoelectric detection device. The MOPA amplification device and the photoelectric detection device are respectively communicatively connected to the phase controller.

6. The miniaturized laser coherent beam combining device based on a polarization grating according to claim 5, characterized in that, The chip used in the MOPA amplification device has an on-chip phase modulation function for semiconductor chips, and its modulation range reaches more than 2π.

7. The miniaturized laser coherent beam combining device based on a polarization grating according to claim 1, characterized in that, The photoelectric detection device includes a photoelectric detector and a signal sampling device. The signal sampling device is an oscilloscope or a data acquisition card.

8. The miniaturized laser coherent beam combining device based on a polarization grating according to claim 4, characterized in that, The fiber collimation device is a fiber collimator, the coupling device is a coupling lens, the beam collimation device is a collimating lens, the adjustment polarization device is a polarization controller, the transformation mirror is a focusing mirror, and the beam splitting device is a beam splitter.

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