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CN-121976295-A - Wave plate suitable for middle-far infrared wave band and application thereof

CN121976295ACN 121976295 ACN121976295 ACN 121976295ACN-121976295-A

Abstract

The invention relates to the technical field of optical devices. And more particularly to a wave plate suitable for mid-far infrared bands and applications thereof. The wave plate is prepared by using a cesium cadmium chloride optical crystal as a birefringent matrix material, wherein the chemical formula of the cesium cadmium chloride optical crystal is CsCdCl 3 , the space group of the cesium cadmium chloride optical crystal is P6 3 /mmc, the cesium cadmium chloride optical crystal belongs to a hexagonal crystal system, the unit cell parameters are a=b= 7.418 a, c=18.39 a, z=6, alpha=beta=90°, and gamma=120°. The cesium-cadmium-chlorine optical crystal has higher transmittance and smaller double refractive index in a long-wave infrared band, so that the prepared wave plate has larger thickness dimension, is convenient to process, is suitable for middle-far infrared band use, has important application prospect in the fields of optics and optical communication, and can be used for preparing various optical devices such as an optical attenuator, a polarization state generator, a polarization direction rotator and the like.

Inventors

  • WU QIAN
  • LI BING
  • XIA MINGJUN
  • TIAN HAOTIAN
  • LI RUKANG
  • WANG TIANYU

Assignees

  • 中国科学院理化技术研究所

Dates

Publication Date
20260505
Application Date
20260205

Claims (10)

  1. 1. The wave plate is characterized in that the wave plate is prepared by using cesium-cadmium-chlorine optical crystals as birefringent matrix materials, wherein the chemical formula of the cesium-cadmium-chlorine optical crystals is CsCdCl 3 , the space group of the cesium-cadmium-chlorine optical crystals is P6 3 /mmc, the cesium-cadmium-chlorine optical crystals belong to a hexagonal system, the unit cell parameters are a=b= 7.418 a, c=18.39 a, z=6, alpha=beta=90 degrees and gamma=120 degrees.
  2. 2. A waveplate according to claim 1, characterized in that the waveplate has an operating wavelength of 532nm, 633nm, 1064nm or 10 μm; preferably, the wave plate is a true zero-order wave plate or a multi-stage wave plate.
  3. 3. The wave plate of claim 2, wherein the wave plate is a zero-order half wave plate or a zero-order quarter wave plate; Preferably, the wave plate is a true zero-order wave plate, the working wavelength of the wave plate is 532nm, the thickness of the corresponding zero-order half wave plate is 17.8 mu m, and the thickness of the corresponding zero-order quarter wave plate is 8.9 mu m; Preferably, the wave plate is a true zero-order wave plate, the working wavelength of the wave plate is 633nm, the thickness of the corresponding zero-order half wave plate is 21.8 mu m, and the thickness of the corresponding zero-order quarter wave plate is 10.9 mu m; Preferably, the wave plate is a true zero-order wave plate, the working wavelength of the wave plate is 1064nm, the thickness of the corresponding zero-order half wave plate is 38.1 μm, and the thickness of the corresponding zero-order quarter wave plate is 19.1 μm; Preferably, the wave plate is a true zero-order wave plate, the working wavelength of the wave plate is 10 μm, the thickness of the corresponding zero-order half wave plate is 245.0 μm, and the thickness of the corresponding zero-order quarter wave plate is 122.5 μm.
  4. 4. The wave plate of claim 2, wherein the wave plate is a multi-stage half wave plate or a multi-stage quarter wave plate; Preferably, the wave plate is a multi-stage wave plate, the working wavelength of the wave plate is 532nm, the thickness of the corresponding multi-stage half wave plate is an odd multiple of 17.8 μm, and the thickness of the corresponding multi-stage quarter wave plate is an odd multiple of 8.9 μm.
  5. 5. The wave plate of claim 1, wherein the cesium cadmium chloride optical crystal has a transmittance of greater than 60% at 0.5-20 μm; Preferably, the cesium cadmium chloride optical crystal has a transmittance of greater than 80% at 1-21 μm.
  6. 6. The wave plate of claim 1, wherein the ultraviolet absorption cutoff wavelength of the cesium cadmium chloride optical crystal is 255-265nm; Preferably, the cesium cadmium chloride optical crystal has a birefringence delta n of 0.0012-0.0022@0.5-20 μm.
  7. 7. The wave plate according to claim 1, wherein the cesium cadmium chloride optical crystal is prepared by the following steps: Uniformly mixing CsCl and CdCl 2 according to the molar ratio of CsCl to CdCl 2 of 1:1, filling into a quartz tube, vacuumizing to 10 -3 -10 -5 Pa, sealing the tube, putting into a muffle furnace, heating to 510-550 ℃ at the speed of 10-40 ℃ per hour, keeping the temperature for 20-40 hours until the reaction is complete, and naturally cooling to room temperature to obtain powder CsCdCl 3 ; Placing the powder CsCdCl 3 into a quartz tube, vacuumizing to 10 -5 Pa, sealing the tube, placing into a crucible descending furnace, heating at a rate of 10-30 ℃ per hour, heating to the upper temperature of 560-600 ℃ and the lower temperature of 510-550 ℃ of the crucible descending furnace, keeping the temperature for 10-30 hours until the raw materials are completely melted, vertically descending the crucible descending furnace at a speed of 1-3mm per hour for crystal growth, and after the crystal growth is finished, cooling to room temperature at a rate of 10-40 ℃ per hour to obtain the cesium cadmium chloride optical crystal.
  8. 8. An optical attenuator comprising a waveplate as claimed in any one of claims 1 to 7.
  9. 9. A polarization state generator comprising a wave plate as claimed in any one of claims 1 to 7.
  10. 10. A polarization rotator comprising a wave plate according to any one of claims 1 to 7.

Description

Wave plate suitable for middle-far infrared wave band and application thereof Technical Field The invention relates to the technical field of optical devices. And more particularly to a wave plate suitable for mid-far infrared bands and applications thereof. Background In the optical field, optical crystals are used as a crystal material with special optical properties, and wave plates manufactured by using the optical crystals have important applications. The wave plate is an optical element capable of generating additional optical path difference (or phase difference) for two beams of light with mutually perpendicular polarization, and is regarded as a core optical element for adjusting laser polarization, and has irreplaceable application value in civil and military fields such as medical imaging, stress detection, laser radar and the like. Wave plates can be classified into zero-order plates and multi-order (phase shift greater than 2pi) plates according to the degree of optical phase shift. Zero-order waveplates have received much attention because of their lower wavelength sensitivity, higher temperature stability, and greater effective acceptance angle. It is known that as the wavelength becomes shorter, the birefringence in the crystal becomes larger. The birefringence of the crystal is critical to its optical function, and crystals with proper birefringence may become materials for preparing polarizing elements. The current high-quality wave plate is mostly made of crystal materials, for example, quartz crystals have lower birefringence, are the most common materials for manufacturing wave plates at present, have a transmission range of 165-4200nm and higher transmittance, and the ultraviolet cut-off edge of magnesium fluoride crystals can reach 110nm, so that the method is more suitable for manufacturing deep ultraviolet wave plate elements. The sapphire crystal and the quartz crystal have similar optical parameters, but the commercialization degree of the quartz wave plate is higher, and the cost is lower. However, the true zero-order thickness of the quartz wave plate, the magnesium fluoride wave plate and the sapphire wave plate is too thin to facilitate polishing, so that the quartz wave plate, the magnesium fluoride wave plate and the sapphire wave plate are generally designed into multi-stage wave plates in the deep ultraviolet region and the visible light region and cannot be used in the middle-far infrared band. With the development of new wavelength lasers, the application of zero-order waveplates with a band covering the deep ultraviolet and far infrared bands has received much attention. In recent years, many research teams have attempted to develop novel waveplate materials with smaller birefringence to increase the thickness of zero-order waveplates and solve the problem of fragility during preparation and use. However, the thickness of the zero-order waveplate is still thin due to the inherent birefringence properties of the existing waveplate materials, which presents significant difficulties in manufacturing and application. Therefore, there is an urgent need to develop new wave plate materials to overcome the problems of the prior art. Disclosure of Invention To solve the above problems, a first object of the present invention is to provide a wave plate suitable for the mid-far infrared band. The wave plate is prepared by taking cesium cadmium chloride optical crystals as birefringent matrix materials, has larger thickness dimension, is convenient to process, and is suitable for application in middle and far infrared wave bands. A second object of the present invention is to provide an optical attenuator. A third object of the invention is to provide a polarization state generator. A fourth object of the present invention is to provide a polarization direction rotator. In order to achieve the first object, the present invention adopts the following technical scheme: The invention discloses a wave plate suitable for a middle-far infrared band, which is prepared by using a cesium-cadmium-chlorine optical crystal as a birefringent matrix material, wherein the chemical formula of the cesium-cadmium-chlorine optical crystal is CsCdCl 3, the space group of the cesium-cadmium-chlorine optical crystal is P6 3/mmc, the cesium-cadmium-chlorine optical crystal belongs to a hexagonal crystal system, the unit cell parameter is a=b= 7.418 a, c=18.39 a, Z=6, alpha=beta=90 degrees and gamma=120 degrees. The cesium-cadmium-chlorine optical crystal selected by the invention has very wide transmission spectrum (0.25-25 μm) and excellent transmittance, the transmittance is more than 60% in the range of 0.5-20 μm, the transmittance is even more than 80% in the range of 1-21 μm, and the cesium-cadmium-chlorine optical crystal has smaller birefringence (delta n=0.0012-0.0022@0.5-20 μm) in the transmission range, and is a crystal material suitable for preparing wave plates, especially has high transmitta