Patent ID: 6661960
Filing Date: 2003-12-09
Classification: G02B

Abstract:
A photodetector for selectively passing and absorbing light based on wavelength, comprising:a substrate; a combined waveguide including a 1Ã—1 multi mode interference (MMI) waveguide on said substrate, a first single mode waveguide connected with an input end of said MMI waveguide and formed on said substrate and a second single mode waveguide connected with an output end of said MMI waveguide and formed on said substrate, and a substrate electrode, wherein a light of wavelength multiplexed signal having at least two wavelength components is incident onto the first single mode waveguide, transmitted therethrough and introduced into the MMI waveguide, and, the combined waveguide is constructed so that a composition in wavelength of a core layer of the MMI waveguide is shorter in wavelength than a first of the wavelength components which is transmitted through the MMI waveguide to be allowed to pass through the second single mode waveguide as single mode, while the composition in wavelength of the core layer is longer in wavelength than a second of the wavelength components which is absorbed by the MMI waveguide; and wherein said second of the wavelength components absorbed by the MMI waveguide is converted to an electrical output signal through said substrate electrode.