Patent ID: 6774348
Filing Date: 2004-08-10
Classification: G01J,H04B

Abstract:
A detector for detecting a light beam having a first wavelength of light and a second wavelength of light, and for providing an indication of a change in power in the first wavelength of light and/or the second wavelength of light, the detector comprisinga first absorbing layer for absorbing a first portion of the first wavelength of light and a second portion of the second wavelength of light, the first absorbing layer having a first conductivity type; a second absorbing layer situated below the first absorbing layer for absorbing a third portion of the second wavelength of light and a fourth portion of the first wavelength of light, the second absorbing layer having the first conductivity type; an intermediate layer situated between the first absorbing layer and the second absorbing layer, the intermediate layer having a second conductivity type; and providing means for providing an indication of a change in power in the first wavelength of light and/or the second wavelength of light using a measure of the light absorption in the first absorbing layer and a measure of the light absorption in the second absorbing layer.