LONG WAVE PASS INFRARED FILTER BASED ON POROUS SEMICONDUCTOR MATERIAL AND THE METHOD OF MANUFACTURING THE SAME
First Claim
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1. An infrared filter comprising:
- a substrate or host silicon wafer having a first surface and a second surface and further including plural holes defined at least partially therethrough, said holes having cross-sections within a selected range of sizes, said holes being spaced by distances within a selected range, wherein said host wafer is transparent over the substantial part of the infrared spectral range;
wherein light with wavelengths smaller than the characteristic size of the hole structure is effectively scattered thus forming a rejection spectral band while the light with wavelengths above said characteristic size of the pore structure is effectively transmitted through the filter thus forming a pass spectral band.
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Abstract
Scattering-type long wave pass filters for the infrared region of the spectrum offer high levels of suppression of the unwanted short-wave radiation, good levels of transmission of the desired long wave radiation combined with good control of the rejection edge position and shape and good mechanical stability of the filter layer. Such filters are well suited for the wide range of applications and can be used in various environments including cryogenic temperatures. Several methods of fabrication of such filters based on electrochemical etching of semiconductor materials in order to form porous layer are provided.
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24 Claims
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1. An infrared filter comprising:
a substrate or host silicon wafer having a first surface and a second surface and further including plural holes defined at least partially therethrough, said holes having cross-sections within a selected range of sizes, said holes being spaced by distances within a selected range, wherein said host wafer is transparent over the substantial part of the infrared spectral range;
wherein light with wavelengths smaller than the characteristic size of the hole structure is effectively scattered thus forming a rejection spectral band while the light with wavelengths above said characteristic size of the pore structure is effectively transmitted through the filter thus forming a pass spectral band.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
Specification