Optical attenuation filter
AssigneeOptical Coating Laboratory, Inc.
InventorsRalf H. Erz, Scott McEldowney, Lauren R. Wendt
Life of this patent
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Abstract
An attenuation filter contains absorbing thin film layers, which comprise gray metals or metal compounds. The attenuation filter offers significant advantages when used in optical communication systems subjected to a relatively high flux of incident light. It was surprisingly discovered that particular thin film materials provide significant protection to the attenuating thin film layer thereby improving the temporal stability and power handling capacity over prior art devices.
Claims19
An optical attenuation filter comprising:
- a substrate having a first surface and a second surface;
- an optical attenuating layer formed on a first portion of said first surface of said substrate, wherein said optical attenuating layer has a variation in thickness across at least one dimension of said substrate, and wherein said first surface of said substrate has a second portion thereof, that is adjacent to said first portion of said first surface said substrate and is exclusive of said optical attenuating layer;
- and
- a first multilayer antireflective coating structure formed on said optical attenuating layer and also on said second portion of said first surface of said substrate, and including a first buffer layer of a refractive index less than 1.65, and one or more additional layers containing at least one layer of a refractive index greater than 1.65, and wherein said first multilayer antireflective coating structure formed on said optical attenuating layer and on said second portion of said first surface of said substrate has a layer arrangement such that said first buffer layer is closer to said optical attenuating layer and closer to said second portion of said substrate than any additional layer having a refractive index greater than 1.65.
A method of attenuating an optical signal comprising the steps of:
- (a) providing an optical attenuation filter that includes
- a substrate having a first and second surfaces,
- an optical attenuating layer formed on at least a first portion of said first surface of said substrate, wherein said optical attenuating layer has a variation in thickness across at least one dimension of said substrate, and wherein said first surface of said substrate has a second portion thereof, that is adjacent to said first portion of said first surface said substrate and is exclusive of said optical attenuating layer, and
- a first multilayer antireflective coating structure formed on said optical attenuating layer and also on said second portion of said first surface of said substrate, and including a first buffer layer of a refractive index less than 1.65, and one or more additional layers containing at least one layer of a refractive index greater than 1.65, and wherein said first multilayer antireflective coating structure formed on said optical attenuating layer and on said second portion of said first surface of said substrate has a layer arrangement such that said first buffer layer is closer to said optical attenuating layer and closer to said portion of said first surface of said substrate than any additional layer having a refractive index greater than 1.65;
- and
- (b) placing said optical attenuation filter provided in step (a) in the path of light to be attenuated.
Dependencies are inferred from the claim text.