The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 30, 2002
Filed:
Nov. 30, 1999
Fred Sugihwo, San Francisco, CA (US);
James S. Harris, Jr., Stanford, CA (US);
The Board of Trustees of The Leland Stanford Junior University, Stanford, CA (US);
Abstract
A light detector comprising a photodetector disposed within an etalon or microcavity. The light detector is sensitive to light having a wavelength resonant with the etalon. Preferably, the etalon is a solid state microcavity having distributed bragg reflectors. The photodetector may be a photodiode, phototransistor or the like. The etalon has a front reflector with reflectivity R and a back reflector with reflectivity R . The photodetector has a double-pass absorption of A. In the present invention, R , R , and A are selected such that R =R (1−A). The combination of the back reflector and absorbing photodetector is indistinguishable from a single reflector of reflectivity R . Therefore, the light detector behaves like an etalon with matched reflectors. Preferably, R is greater than 0.95 and R is greater than 0.98. The photodetector can have a relatively thin absorption layer, thereby providing high speed capability. Even with a low absorption, the photodetector provides high quantum efficiency since it is within the etalon. Preferably, the front reflector is movable such that an etalon cavity length is adjustable. This provides for adjustment of the wavelength at which the light detector is sensitive.