High-gain extraction multi-pass oscillation intermediate infrared laser

Abstract

The invention discloses a high-gain extraction multi-pass oscillation mid-infrared laser. Belongs to the technical field of laser, and particularly relates to the technical field of multi-pass oscillation mid-infrared lasers. The technical problems that a laser is complex in structure and large in size due to the fact that oscillation light is subjected to multi-pass folding through a complex cavity type and reciprocates back and forth to a crystal for gain for multiple times, and the center position of the crystal cannot be fully utilized at present are solved. By adopting the high-gain extraction multi-pass oscillation mid-infrared laser based on the regular polygon crystal structure, oscillation light is subjected to turn-back oscillation in a polygonal star-awn light path form in the crystal around the center of the crystal, so that a gain acquisition area is homogenized, the gain extraction efficiency of the laser is improved, and the gain extraction efficiency of the laser is improved. And a conventional multi-pass gain cavity structure is simplified, and the structure is simple and compact.

Description

Technical Field

[0001] The invention belongs to the field of laser technology, and specifically relates to the technical field of multi-pass oscillation mid-infrared lasers. Background Art

[0002] Mid-infrared solid lasers based on rare earth ion doping Er:YSGG, Er:YAG, etc., have a self-termination effect and low resonant cavity gain, which makes it difficult to increase power and has low light-to-light conversion efficiency because the upper energy level lifetime is much shorter than the lower energy level lifetime. At the same time, due to the need for high pump energy excitation, lasers are often accompanied by serious thermal effects. At present, the technology of rod-shaped mid-infrared lasers using multi-dimensional side pumping is relatively mature. Multiple semiconductor Bar lasers are used to side-pump rod-shaped crystals, and the pump light field is homogenized to improve the damage threshold of the crystal. However, this method actually increases the output energy by increasing the pump energy, and the light-to-light conversion efficiency is not increased. However, the semiconductor pump source technology of mid-infrared lasers is not perfect, the thermal performance of the crystal itself is poor, and the damage threshold is low. An efficient thermal management system is required. These factors greatly affect the improvement of the energy conversion efficiency of mid-infrared lasers. The method of using complex cavity types to fold the oscillating light in multiple passes, so that it can go back and forth to the crystal for gain multiple times, and improve the output power and light-to-light conversion efficiency, has a complex structure and a large volume, and currently cannot fully utilize the center position of the crystal. Summary of the invention

[0003] In order to solve the technical problem that a complex cavity type is used in the past to perform multi-pass folding on the oscillating light so that the oscillating light can go back and forth to the crystal for gain multiple times, thereby resulting in a complex laser structure, a large volume, and currently the center position of the crystal cannot be fully utilized, the present invention provides a high-gain extraction multi-pass oscillation mid-infrared laser, comprising a semiconductor pump source, a coupling mirror group, a total reflection mirror, an output mirror and a regular polygonal crystal; the regular polygonal crystal has an odd number of sides, one of which is an output side, and the surface where the side is located is plated with a laser anti-reflection film, and the other sides are reflection sides, and the surfaces where the other sides are located are plated with laser reflection films, each reflection side receives corresponding pumping light emitted by a semiconductor pump source, and a coupling mirror group is arranged between the reflection side and the semiconductor pump source, the total reflection mirror and the output mirror are arranged on one side of the output side, and the total reflection mirror and the output mirror are used to limit the laser beam in the regular polygonal crystal to form oscillation, and finally realize laser output at the output mirror.

[0004] Furthermore, the coupling mirror group is composed of two cross-placed cylindrical lenses, which are used to focus and couple the pump light emitted by the semiconductor pump source, and then pump the regular polygonal crystal.

[0005] Furthermore, the total reflection mirror is placed on a straight line which forms an angle of 90 / n° with the output edge of the regular polygonal crystal, where n represents the number of edges of the regular polygonal crystal.

[0006] Furthermore, the output mirror is placed on a straight line that forms an angle of 90 / n° with the output side of the regular polygonal crystal, where n represents the number of sides of the regular polygonal crystal, and the perpendicular bisector of the output mirror and the perpendicular bisector of the total reflection mirror form the same angle with the perpendicular bisector of the output side of the regular polygonal crystal.

[0007] Furthermore, when the mid-infrared laser is working, the regular polygonal crystal is placed between two water-cooled and polished copper heat sinks for cooling.

[0008] The beneficial effects of the mid-infrared laser of the present invention are: By adopting a high-gain extraction multi-pass oscillation mid-infrared laser based on a regular polygonal crystal structure, the oscillating light is made to oscillate in the form of a polygonal star-shaped light path inside the crystal around the center of the crystal, thereby homogenizing the area where gain is obtained, improving the laser gain extraction efficiency, and simplifying the conventional multi-pass gain cavity structure, which is simple and compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a structural diagram of a mid-infrared laser in an embodiment of the present invention; Figure 2 Schematic diagram of two cross-placed cylindrical lenses in an embodiment of the present invention; Figure 3 Schematic diagram of the optical path of a 7-pointed star corresponding to a regular 7-sided crystal in an embodiment of the present invention; Figure 4 Schematic diagram of the 9-pointed star light path corresponding to the regular 9-gon crystal in an embodiment of the present invention. DETAILED DESCRIPTION

[0010] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0011] Embodiment 1, In this embodiment, in order to solve the problem of low gain of rare earth ion-doped laser crystals such as Er:YSGG and Er:YAG, a high-gain extraction multi-pass oscillation mid-infrared laser based on a regular polygonal crystal structure is proposed, so that the oscillating light performs a return oscillation in the form of a polygonal star-shaped optical path inside the crystal and around the center of the crystal, thereby homogenizing the area where gain is obtained, improving the laser gain extraction efficiency, and simplifying the conventional multi-pass gain cavity structure, with a simple and compact structure.

[0012] The mid-infrared laser comprises a semiconductor pump source 1, a coupling mirror group 2, a total reflection mirror 3, an output mirror 4 and a regular polygonal crystal 5; the regular polygonal crystal 5 has an odd number of sides, one of which is an output side, and the surface where the side is located is coated with a laser anti-reflection film to reduce the light energy loss when the oscillating light enters and emits the crystal; the remaining sides are reflection sides, and the surfaces where the remaining sides are located are coated with a laser reflection film to make the laser reflect multiple times in the crystal, each reflection side corresponds to receiving a pump light emitted by a semiconductor pump source 1, and a coupling mirror group 2 is arranged between the reflection side and the semiconductor pump source 1, the total reflection mirror 3 and the output mirror 4 are arranged on one side of the output side, and the total reflection mirror 3 and the output mirror 4 are used to limit the laser beam in the regular polygonal crystal 5 to form oscillation, and finally realize laser output at the output mirror 4.

[0013] The coupling lens assembly 2 is composed of two cross-placed cylindrical lenses, which are placed at the following positions: Figure 2 As shown, it is used to perform focusing coupling on the pump light emitted by the semiconductor pump source 1, and then pump the regular polygonal crystal 5 to increase the overlap rate between the pump light and the resonant cavity laser mode.

[0014] The total reflection mirror 3 is placed on a straight line which forms an angle of 90 / n° with the output edge of the regular polygonal crystal 5, where n represents the number of edges of the regular polygonal crystal.

[0015] The output mirror 4 is placed on a straight line that forms an angle of 90 / n° with the output side of the regular polygonal crystal 5, wherein n represents the number of sides of the regular polygonal crystal, and the perpendicular bisector of the output mirror 4, the perpendicular bisector of the total reflection mirror 3 and the perpendicular bisector of the output side of the regular polygonal crystal 5 form the same angle.

[0016] When n=7, the placement positions of the total reflection mirror 3 and the output mirror 4 are as follows Figure 3 shown.

[0017] When the mid-infrared laser is working, the regular polygonal crystal 5 is placed between two water-cooled and polished copper heat sinks for cooling.

[0018] Embodiment 2, This embodiment is a further example of the embodiment 1. The regular polygon crystal 5 is a regular polygon lath structure with an odd number of sides. If the number of sides of the regular polygon is n, then n-1 faces are reflection faces and 1 face is the laser incident and exit face. The laser enters the crystal from the incident and exit faces of the regular n-gon lath crystal. The laser undergoes n-1 reflections in the crystal, forms an n-angled star-shaped light propagation path around the center of the crystal, and then exits the crystal from the same face.

[0019] The regular polygonal crystal structure and the corresponding optical path design provided in this embodiment are as follows: Figure 3 As shown, the regular 7-sided crystal corresponds to a 7-pointed star light path, such as Figure 4As shown, a regular 9-gon crystal corresponds to a 9-angled star optical path, and a regular n-gon crystal corresponds to an n-angled star optical path. Through a multi-angled star optical path design, each oscillation of the laser is closely surrounded by the center of the crystal, and the gain area in the crystal is efficiently and uniformly extracted.

Claims

1. A high-gain extraction multi-pass oscillation mid-infrared laser, characterized in that: The mid-infrared laser comprises a semiconductor pump source (1), a coupling mirror group (2), a total reflection mirror (3), an output mirror (4) and a regular polygonal crystal (5); the regular polygonal crystal (5) has an odd number of sides, one of which is an output side, the surface of which is coated with a laser anti-reflection film, the remaining sides are reflection sides, the surfaces of which are coated with laser reflection films, each reflection side correspondingly receives pump light emitted by a semiconductor pump source (1), and a coupling mirror group (2) is arranged between the reflection side and the semiconductor pump source (1), the total reflection mirror (3) and the output mirror (4) are arranged on one side of the output side, and the total reflection mirror (3) and the output mirror (4) are used to limit the laser beam within the regular polygonal crystal (5) to form oscillation, and finally realize laser output at the output mirror (4).

2. The high-gain extraction multi-pass oscillation mid-infrared laser according to claim 1, characterized in that: The coupling mirror group (2) is composed of two cross-placed cylindrical lenses and is used to perform focusing coupling on the pump light emitted by the semiconductor pump source (1) and then pump the regular polygonal crystal (5).

3. The high-gain extraction multi-pass oscillation mid-infrared laser according to claim 2, characterized in that: The total reflection mirror (3) is placed on a straight line at an angle of 90 / n° with the output edge of the regular polygonal crystal (5), wherein n represents the number of edges of the regular polygonal crystal.

4. The high-gain extraction multi-pass oscillation mid-infrared laser according to claim 3, characterized in that: The output mirror (4) is placed on a straight line that forms an angle of 90 / n° with the output side of the regular polygonal crystal (5), and the perpendicular bisector of the output mirror (4), the perpendicular bisector of the total reflection mirror (3) and the perpendicular bisector of the output side of the regular polygonal crystal (5) form the same angle.

5. The high-gain extraction multi-pass oscillation mid-infrared laser according to claim 4, characterized in that: When the mid-infrared laser is working, the regular polygonal crystal (5) is placed between two water-cooled polished copper heat sinks for cooling.

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