Honeywell G.m.b.h.

Ronald E Peterson

William W Durand

Anil K Jain

Sau K Lo

A nonlinear tunable optical bandpass filter of the Fabry-Perot type is disclosed comprising an optically transparent substrate and a plurality of multilayer coatings deposited on a facing side of the substrate. One of the coating layers comprises a spacer being a nonlinear optical coating material having an externally-variable refractive index. The spacer is bounded on two ends by structures of multilayer stacks being alternating thin films of transparent, physically compatible materials. The filter of the invention can be tuned to pass various transmittance wavelengths through the application of external activation apparatus, such as heating by a laser acting on the spacer.

Nonlinear tunable optical bandpass filter

A tunable Fabry-Perot filter device including at least three low index substrates having a refractive index less than 2.4 and mounted in parallel relationship so as to present two pairs of facing sides to each other in an optical path and a high index, non-metallic or non-absorbing coating having a refractive index of at least 4.0, the high index coating being placed on the facing sides of each of said low index substrates with the thickness of the coating on at least one of the pairs of facing sides being less than the thickness of the coating on the other of the pairs of facing sides, and spacer means for mounting said low index substrates and adjusting the distance between said facing sides. Preferred substrates are potassium halides, cesium halides, and zinc selenide. High index, non-metallic or non-absorbing coatings are preferably from the group of lead telluride, bismuth telluride, germanium telluride and germanium. A high index coating normally has an optical thickness less than or equal to one-half of the minimum wavelength of light to be transmitted through the device. In a preferred embodiment, the spacer means is adapted to adjust one of said pairs of faces to pass the desired wavelength and the other of said pairs of faces is adjusted to pass a wide band width less than the separation between the multiple anharmonic bands. In another preferred embodiment, the spacer means is adapted to adjust one of said pairs to transmit a desired wavelength and the other of said pairs of faces is adjusted to transmit one of the multiple anharmonic bands at the desired wavelength such that only the desired wavelength is precisely tuned at said pairs.

Tunable Fabry-Perot filter

An optical filter comprising a first substance which is substantially transparent to light within a selected first frequency range and having a first index of refraction; and a second substance which has at least one resonance frequency within said first frequency range and having a second index of refraction which is substantially the same as said first index of refraction at all of the frequencies within said first frequency range except for frequencies near said resonance frequency.

Optical filter

A tunable Fabry-Perot filter for transmitting light in the wavelength range from 3-40 microns is disclosed wherein a pair of low index substrates of refractive index less than 2.4 and positioned between an adjustable spacer means have, on their facing sides, a non-metallic coating of refractive index of at least 4.0 and of optical thickness less than one-half the minimum wavelength to be transmitted. Preferred substrates are potassium halides, cesium halides, and zinc selenide, and preferred high index coatings are from the group of lead telluride, bismuth telluride, germanium telluride and germanium.

A Fabry-Perot filter device comprising a pair of low index substrates having a refractive index of less than 2.4 and mounted in parallel relationship so as to present facing sides to each other in an optical path. A coating is placed on the facing sides of each of said low index substrates, the coating having an increasing index of refraction away from the sides from about that of the substrate to above 4.0 such that the index increases in increments of from at least 2 steps to continuously. The total coating thickness is on the order of the light wavelength or more. Means are also provided to adjust the distance between the two faces, at least from a distance of from substantially less than a desired wavelength to at least one-half of the desired wavelength.

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Shoreview, MN, United States of America

Ronald E Peterson