Laser output coupler
The invention pertains to a laser apparatus which includes a laser cavity containing a laser medium, such as methyl fluoride or formic acid, which has a characteristic wavelength in the far infrared region of the spectrum. The laser cavity has first and second opposing mirrors which also respectively serve as an input mirror for the pumping radiation and an output coupling mirror. The invention is an improved output coupler which serves as one of the first and second opposing mirrors. A metal layer having a multiplicity of apertures therein is provided. At least one layer of dielectric material is disposed over the metal layer. The dielectric material is selected to be substantially reflective of infrared radiation (at least 80% reflective) and substantially transmitting of far infrared radiation (at least 80% transmissive). The reflectivity of the output coupler to far infrared radiation is selected by choosing the aperture size and shape of the metal layer. Applicant has discovered that a quarter wave stack of layers of germanium and calcium fluoride provide a high degree of reflectance of the infrared pump radiation while being highly transmissive of the far infrared. Accordingly, these dielectric materials, in conjunction with a metallic grid of, for example, aluminum or nickel, provide a highly efficient output coupler.
- Assignee:
- Univ. of Illinois Foundation
- Patent Number(s):
- US 4023119
- OSTI ID:
- 7324331
- Country of Publication:
- United States
- Language:
- English
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