Four-way coaxial laser amplifier

Abstract

The utility model discloses a four-way coaxial laser amplifier which comprises an isolator, two polarization splitting prisms, a Faraday rotator, two wave plates, a laser crystal, a dichroscope and two reflectors. And the light path passes through the laser crystal for four times and is amplified through components such as a plurality of wave plates, a plurality of reflectors and a Faraday rotator, and the light beam passes through the same part of the laser crystal. According to the four-way coaxial laser amplifier, the light beam passes through the laser crystal for four times through ingenious structural arrangement and is amplified, the utilization rate and the extraction efficiency of the pump light are effectively improved, meanwhile, the space occupation of the amplifier is reduced, and the quality of the output amplified laser is improved.

Description

Technical Field

[0001] The present application relates to the field of laser amplifiers, and in particular to a four-way coaxial laser amplifier. Background Art

[0002] The multi-pass amplifier uses a set of mirrors to repeatedly reflect the signal light, allowing it to pass through the laser crystal multiple times. This design makes more full use of the inversion population of the laser crystal, thereby improving the amplification efficiency.

[0003] However, existing multi-pass amplifiers have some problems. For example, there is a certain angle when each laser passes through the laser crystal, so the medium in a different part of the laser crystal is extracted each time; the overall structure is complex and large in size, which reduces the extraction efficiency; it usually does not exceed four passes, and there is a large amount of amplified spontaneous emission (ASE). Utility Model Content

[0004] The present application mainly provides a four-pass coaxial laser amplifier to solve the problem of low light utilization rate in existing multi-pass amplifiers.

[0005] To solve the above technical problems, a technical solution adopted in this application is to provide a four-way coaxial laser amplifier, comprising:

[0006] Isolator, first polarization beam splitter, Faraday rotator, half wave plate, second polarization beam splitter, laser crystal, dichroic mirror, quarter wave plate, first reflector and second reflector,

[0007] The external seed light is incident on the isolator and the first polarization beam splitter prism in sequence and becomes the first polarized light. The first polarization beam splitter prism deflects the polarization direction of the light beam. The first polarized light is then incident on the Faraday rotator and the half-wave plate in sequence and becomes the second polarized light. The second polarized light has the same polarization direction as the first polarized light. The second polarized light is then incident on the second polarization beam splitter prism and the laser crystal in sequence for amplification and becomes the third polarized light. The third polarized light is incident on the dichroic mirror and the quarter-wave plate in sequence and then reaches the first reflector. Thereafter, the light path is reflected along the original path and passes through the quarter-wave plate in sequence. The light is incident on the laser crystal, the dichroic mirror, the laser crystal and the second polarization beam splitter prism, is reflected by the second polarization beam splitter prism and reaches the second reflector, is reflected by the surface of the second reflector and returns to the second polarization beam splitter prism along the original optical path, is reflected and enters the laser crystal, the dichroic mirror, the quarter-wave plate again, and reaches the first reflector, is reflected and returns to the original path, passes through the quarter-wave plate, the dichroic mirror, the laser crystal, the second polarization beam splitter prism, the half-wave plate, the Faraday rotator, and the first polarization beam splitter prism in sequence, and is reflected by the first polarization beam splitter prism and then emitted.

[0008] In a possible implementation, the four-way coaxial laser amplifier further includes a laser shaping system, and the laser shaping system is provided between the isolator and the first polarization beam splitter prism.

[0009] In a possible implementation, the laser shaping system includes a beam expansion lens group and / or a beam reduction lens group.

[0010] In a possible implementation, the laser shaping system includes a focusing lens.

[0011] In a possible implementation, the four-way coaxial laser amplifier further includes a pumping system, which is disposed on a side of the dichroic mirror away from the laser crystal, and couples pumping light to the laser crystal.

[0012] In a possible implementation, the dichroic mirror coating is configured to totally reflect the seed light wavelength and to increase the transmittance of the pump light.

[0013] In a possible implementation, the four-way coaxial laser amplifier further includes a shaping mirror, which is disposed between the laser crystal and the dichroic mirror.

[0014] In a possible implementation, the laser crystal is a crystal without polarization characteristics.

[0015] In a possible implementation, the laser crystal is a Nd:YAG crystal.

[0016] In a possible implementation, the laser crystal is a Yb:YAG crystal.

[0017] The beneficial effect of the present application is that, different from the prior art, the present application discloses a four-way coaxial laser amplifier, which, through a clever structural arrangement, allows the light beam to pass through the laser crystal four times and be amplified, thereby effectively improving the utilization rate and extraction efficiency of the pump light, while reducing the space occupied by the amplifier and improving the quality of the output amplified laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0019] Figure 1 It is a structural diagram of an embodiment of a four-way coaxial laser amplifier in this application.

[0020] Description of main component symbols:

[0021] 100-Four-way coaxial laser amplifier; 10-Isolator; 20-Laser shaping system; 31-First polarization beam splitter prism; 32-Second polarization beam splitter prism; 40-Faraday rotator; 51-Half-wave plate; 52-Quarter-wave plate; 60-Laser crystal; 70-Dichroic mirror; 81-First reflector; 82-Second reflector; 90-Shaping mirror; 110-Pump system. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] The terms "first", "second" and "third" in the embodiments of the present application are only used for descriptive purposes and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second" and "third" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally also include steps or units that are not listed, or may optionally also include other steps or units inherent to these processes, methods, products or devices.

[0024] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] See also Figure 1 , the present application proposes a four-way coaxial laser amplifier 100, comprising:

[0026] The isolator 10, the first polarization beam splitter prism 31, the Faraday rotator 40, the half-wave plate 51, the second polarization beam splitter prism 32, the laser crystal 60, the dichroic mirror 70, the quarter-wave plate 52, the first reflector 81 and the second reflector 82,

[0027] The external seed light is incident on the isolator 10 and the first polarization beam splitter prism 31 in sequence and becomes the first polarized light. The first polarization beam splitter prism 31 deflects the polarization direction of the light beam. The first polarized light is then incident on the Faraday rotator 40 and the half-wave plate 51 in sequence and becomes the second polarized light. The second polarized light has the same polarization direction as the first polarized light. The second polarized light is then incident on the second polarization beam splitter prism 32 and the laser crystal 60 in sequence for amplification and becomes the third polarized light. The third polarized light is incident on the dichroic mirror 70 and the quarter-wave plate 52 in sequence and then reaches the first reflector 81. This is the first optical path. After that, the light path is reflected along the original path and passes through the quarter-wave plate 52 and the dichroic mirror 70 in sequence. , laser crystal 60 and second polarization beam splitter prism 32, is reflected by the second polarization beam splitter prism 32 and reaches the second reflector 82, which is the second optical path. After being reflected by the surface of the second reflector 82, it returns to the second polarization beam splitter prism 32 along the original optical path, is reflected and enters the laser crystal 60, dichroic mirror 70, quarter-wave plate 52 again, and reaches the first reflector 81, which is the third optical path. After reflection, it returns to the original path, passes through the quarter-wave plate 52, dichroic mirror 70, laser crystal 60, second polarization beam splitter prism 32, half-wave plate 51, Faraday rotator 40, first polarization beam splitter prism 31 in sequence, and is reflected by the first polarization beam splitter prism 31 before being emitted.

[0028] In the four-way coaxial laser amplifier 100 of this embodiment, a light beam first enters the isolator 10, is filtered by the first polarization beam splitter prism 31 to be horizontally polarized first polarized light, and then passes through the Faraday rotator 40 and the half-wave plate 51. At this time, the polarization direction of the second polarized light is still horizontal. The second polarized light then passes through the second polarization beam splitter prism 32 and enters the laser crystal 60 for amplification. The amplification includes laser amplification or pulse amplification. The amplified third polarized light enters the dichroic mirror 70, undergoes anti-reflection, is rotated by the quarter-wave plate 52, is reflected by the first reflector 81, and is rotated again by the quarter-wave plate 52. At this time, the light beam is rotated exactly 90° and its polarization direction becomes vertical. It then returns along the optical path, passes through the dichroic mirror 70 and the laser crystal 60 in sequence, is amplified again, and then passes through the second polarization beam splitter prism 32. At this time, because the polarization direction has become vertical, it is reflected by the second polarization beam splitter prism 32 and enters the second reflector 82. After being reflected by the second reflector 82, it returns along the original optical path. After being reflected by the second polarization beam splitter prism 32, the light beam passes through the laser crystal 60 again and is amplified. It then passes through the dichroic mirror 70, the quarter-wave plate 52, and the first reflector 81 in sequence and enters the fourth optical path. After passing through the quarter-wave plate 52 and the first reflector 81, and then passing through the quarter-wave plate 52, the dichroic mirror 70, and the laser crystal 60 in sequence, it reaches the second polarization beam splitter prism 32. At this time, the light beam has undergone another 90° rotation and its polarization direction has returned to the horizontal direction. Therefore, it directly transmits the second polarization beam splitter prism 32 and passes through the half-wave plate 51 and the Faraday rotator 40. At this time, the polarization direction is changed to vertical polarization. Therefore, it reaches the first polarization beam splitter prism 31 again, is reflected, and is emitted from the four-way coaxial laser amplifier 100.

[0029] In the four-way coaxial laser amplifier 100 of this embodiment, the light beam is amplified four times in total, which greatly improves the utilization rate of the pump light, while making the device structure smaller, reducing space occupation, and improving the quality of the output laser.

[0030] In one embodiment, the four-way coaxial laser amplifier further includes a laser shaping system 20 , which is disposed between the isolator 10 and the first polarization beam splitter prism 31 and is used to shape and optimize the light beam so that the signal light can achieve maximum extraction efficiency in the crystal.

[0031] In one embodiment, the laser shaping system 20 includes a beam expansion lens group and / or a beam reduction lens group, and the beam expansion lens group and the beam reduction lens group are used to change the diameter and divergence angle of the light beam.

[0032] In one embodiment, the laser shaping system 20 includes a focusing lens for adjusting the focal length of the light beam.

[0033] In one embodiment, the quad coaxial laser amplifier 100 further includes a pumping system 110 . The pumping system 110 is disposed on a side of the dichroic mirror away from the laser crystal. The pumping system 110 couples pump light to the laser crystal. Figure 1 Schematic diagram shows the coupling lens group part in the pump system 110, which is used to couple the semiconductor pump laser output from the optical fiber into the laser crystal 60.

[0034] The pump laser passes through the dichroic mirror 70 and is incident along the same optical path as the seed light until it reaches the laser crystal 60 , inputting energy into the laser crystal 60 to excite the laser crystal 60 .

[0035] In one embodiment, the dichroic mirror 70 is coated to fully reflect the seed light wavelength and enhance the transmittance of the pump light, thereby reflecting the seed light beam while allowing the pump light from the other side to transmit to the laser crystal 60, thereby achieving excitation of the laser crystal 60.

[0036] In one embodiment, the quad coaxial laser amplifier 100 further includes a shaping mirror 90 . The shaping mirror 90 is disposed between the laser crystal 60 and the dichroic mirror 70 . The shaping mirror 90 is used to prevent parasitic laser oscillation.

[0037] In one embodiment, the laser crystal 60 is a non-polarization crystal, such as Nd:YAG crystal, Yb:YAG crystal, etc.

[0038] In one embodiment, the dichroic mirror 70 is coated to provide total reflection at the seed light wavelength and anti-reflection at the pump light wavelength.

[0039] In one embodiment, the first polarized light is in a horizontal polarization direction.

[0040] In one embodiment, the incident angle of the light beam entering the first reflector 81 and the second reflector 82 is 0°, so as to ensure that the light beam can accurately return along the original optical path and enter various components after being reflected.

[0041] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A four-way coaxial laser amplifier, characterized in that: include: Isolator, first polarization beam splitter, Faraday rotator, half wave plate, second polarization beam splitter, laser crystal, dichroic mirror, quarter wave plate, first reflector and second reflector, The external seed light is incident on the isolator and the first polarization beam splitter prism in sequence and becomes the first polarized light. The first polarization beam splitter prism deflects the polarization direction of the light beam. The first polarized light is then incident on the Faraday rotator and the half-wave plate in sequence and becomes the second polarized light. The second polarized light has the same polarization direction as the first polarized light. The second polarized light is then incident on the second polarization beam splitter prism and the laser crystal in sequence for amplification and becomes the third polarized light. The third polarized light is incident on the dichroic mirror and the quarter-wave plate in sequence and then reaches the first reflector. Thereafter, the light path is reflected along the original path and passes through the quarter-wave plate in sequence. The light is incident on the laser crystal, the dichroic mirror, the laser crystal and the second polarization beam splitter prism, is reflected by the second polarization beam splitter prism and reaches the second reflector, is reflected by the surface of the second reflector and returns to the second polarization beam splitter prism along the original optical path, is reflected and enters the laser crystal, the dichroic mirror, the quarter-wave plate again, and reaches the first reflector, is reflected and returns to the original path, passes through the quarter-wave plate, the dichroic mirror, the laser crystal, the second polarization beam splitter prism, the half-wave plate, the Faraday rotator, and the first polarization beam splitter prism in sequence, and is reflected by the first polarization beam splitter prism and then emitted.

2. The four-way coaxial laser amplifier according to claim 1, characterized in that: The device further comprises a laser shaping system, which is arranged between the isolator and the first polarization beam splitter prism.

3. The four-way coaxial laser amplifier according to claim 2, characterized in that: The laser shaping system includes a beam expansion lens group and / or a beam reduction lens group.

4. The four-way coaxial laser amplifier according to claim 2, characterized in that: The laser shaping system includes a focusing lens.

5. The four-way coaxial laser amplifier according to claim 1, characterized in that: The invention also includes a pumping system, which is arranged on a side of the dichroic mirror away from the laser crystal, and couples pumping light to the laser crystal.

6. The four-way coaxial laser amplifier according to claim 5, characterized in that: The dichroic mirror coating is for total reflection of the seed light wavelength and for enhancing the transmittance of the pump light.

7. The four-way coaxial laser amplifier according to claim 1, characterized in that: It also includes a shaping mirror, which is arranged between the laser crystal and the dichroic mirror.

8. The four-way coaxial laser amplifier according to claim 1, characterized in that: The laser crystal is a crystal without polarization characteristics.

9. The four-way coaxial laser amplifier according to claim 8, characterized in that: The laser crystal is a Nd:YAG crystal.

10. The four-way coaxial laser amplifier according to claim 8, characterized in that: The laser crystal is a Yb:YAG crystal.

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