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CN-121995558-A - Long wave infrared laser reflector with three-medium structure

CN121995558ACN 121995558 ACN121995558 ACN 121995558ACN-121995558-A

Abstract

The invention provides a long-wave infrared laser reflector with a three-medium structure, which comprises a substrate Sub, a transition layer B, a metal layer G, a medium film system C and an air layer A from bottom to top. The dielectric film system C is characterized by being formed by alternately stacking one or more groups of materials with high, medium and low refractive indexes. The purpose of the invention is to achieve high reflection in the long-wave infrared band. By careful design, three distributions of materials with high, medium, and low different refractive indices are reasonably arranged in the mirror. This strategy effectively reduces mirror absorption by balancing the low absorption of the chalcogenide with the low refractive index of the fluoride, and significantly reduces the temperature rise due to the absorbed heat while increasing the reflectivity. Thus, the continuous laser damage threshold of the reflector is greatly enhanced in theory, so that the reflector exhibits higher stability and tolerance in the face of continuous laser irradiation.

Inventors

  • GUO MENG
  • JIANG JIANWEN
  • JIANG JING
  • SHAO YUCHUAN

Assignees

  • 中国科学院上海光学精密机械研究所

Dates

Publication Date
20260508
Application Date
20241105

Claims (8)

  1. 1. The long-wave infrared laser reflector with the three-medium structure is characterized by sequentially comprising a substrate Sub, a transition layer B, a metal layer G, a medium film system C and an air layer A from bottom to top, wherein the medium film system C is formed by alternately depositing a group of medium materials with high, medium and low refractive indexes, and the design optimization is completed on the basis of an initial film system structure; The dielectric film system C structure is (xLyMzH)/(n), wherein L is a low refractive index material with optical thickness of lambda/4, M is a medium refractive index material with optical thickness of lambda/4, H is a high refractive index material with optical thickness of lambda/4, n is a period number, and x, y and z are thickness coefficients of film layers of the low refractive index, the medium refractive index and the high refractive index materials respectively.
  2. 2. The three-medium structure long wave infrared laser reflector of claim 1, wherein the medium film period number n is 1-10, and the film thickness coefficients x, y and z are 0.1-3.
  3. 3. The long wave infrared laser mirror of claim 1 or 2, wherein the substrate material is Cu, mo, ge, si, chalcogenide glass, znSe, znS.
  4. 4. The long wave infrared laser mirror of claim 1 or 2, wherein the transition layer material is Cr or inconel.
  5. 5. The long wave infrared laser mirror of claim 1 or 2, wherein the metal layer material is Au, ag, al.
  6. 6. The long wave infrared laser mirror of claim 1 or 2, wherein the high refractive index dielectric material is Ge or PbTe.
  7. 7. The long wave infrared laser mirror of claim 1 or 2, wherein the medium refractive index dielectric material is ZnSe or ZnS.
  8. 8. The long wave infrared laser mirror of claim 1 or 2, wherein the low refractive index dielectric material is BaF 2 、YF 3 、YbF 3 .

Description

Long wave infrared laser reflector with three-medium structure Technical Field The invention relates to the technical field of laser, in particular to a long-wave infrared laser reflector with a three-medium structure, and belongs to the technical field of film optics. Background The long-wave infrared laser reflector is a key for laser transmission, is applied to the inside and outside of a laser tube, and is used for promoting laser oscillation, shortening the tube length, optimizing the light path and improving the design efficiency and the laser efficiency. Metal or dielectric coatings are often used. In a radio frequency slab laser, a mirror is paired with an electrode to form a gain region where the laser is circularly amplified to form a stable output. Currently, the preparation of the long-wave infrared laser reflector mostly adopts single metal coating, pure medium coating or traditional molybdenum mirror polishing and other processes. However, as technology advances, research into optimization of mirror performance is also continually in progress. For example, patent application (CN 111505753 a) discloses a carbon dioxide laser reflective film based on a silicon carbide substrate, which is designed by a multilayer structure, comprising a silicon carbide substrate layer, a diamond-like film layer, a nichrome bonding layer, a metal film, and alternately arranged Ge layer and ZnS layer, and alternately arranged YbF 3 layer and ZnSe layer, to achieve a reflectivity of 99.8% in the far infrared 10.6 μm band. The patent application (CN 115508930A) explores a preparation method of an infrared high-reflectivity film, wherein the film is formed by stacking a gold film and ZnS and Ge alternating dielectric films, and the average reflectivity of the reflecting mirror is over 99.7 percent in a wavelength range of 3-5 mu m. The patent application (CN 116413844 a) proposes an innovative carbon dioxide laser mirror design consisting of a silicon substrate, a nichrome transition layer, a metallic silver reflective layer, alternating ZnS and Ge layers, and an outer boron carbide layer. By precisely controlling the thickness of each film, the mirror achieves an average reflectivity of over 99.5% in the long wavelength interval of 8-12 μm. The patent realizes the remarkable improvement of the reflectivity of the long-wave infrared laser reflector by overlapping high-low refractive index medium layers on the metal film, however, the reflection effect is still limited, and the 99.9% reflectivity standard in the extreme environment cannot be fully achieved. Particularly in continuous laser applications, the problem of significant temperature rise due to too high absorption results in a decrease in the mirror damage threshold. Disclosure of Invention Aiming at the problems that the reflectivity is still insufficient in the prior art and the performance characteristics that the chalcogenide is generally low in absorption but the fluoride is relatively low in refractive index, the invention provides a long-wave infrared laser reflector with a three-medium structure. The reflecting mirror aims to effectively reduce the absorption of the reflecting mirror to laser and remarkably improve the laser reflectivity by skillfully combining the low absorption characteristic of the chalcogenide compound and the low refractive index characteristic of fluoride, so that the temperature rise effect of the reflecting mirror is reduced. The technical scheme of the invention is as follows: The infrared laser reflector with the three-medium structure comprises a substrate Sub, a transition layer B, a metal layer G, a medium film system C and an air layer A from bottom to top, wherein the medium film system C is formed by alternately depositing a group of medium materials with high, medium and low refractive indexes, and the design optimization is completed on the basis of an initial film system structure, and the infrared laser reflector with the three-medium structure is mainly characterized in that the medium film system C is (xLyMzH)/(n), wherein L is a low refractive index material with the optical thickness of lambda/4, M is a medium refractive index material with the optical thickness of lambda/4, H is a high refractive index material with the optical thickness of lambda/4, n is a period number, and x, y and z are respectively film layer thickness coefficients of the low refractive index, the medium refractive index and the high refractive index material. The medium film period number n is 1-10, and the film thickness coefficients x, y and z of the low refractive index, the medium refractive index and the high refractive index materials are 0.1-3. The substrate material is Cu, mo, ge, si, chalcogenide glass, znSe or ZnS. The transition layer is made of Cr or chrome-nickel alloy. The metal layer is made of Au, ag and Al. The high refractive index dielectric material is Ge or PbTe. The medium refractive index medium material is ZnSe or