Patent ID: 8036499
Filing Date: 2011-10-11
Classification: G02F

Abstract:
1. An acousto-optic filter comprising: a substrate; an optical waveguide provided on the substrate; and a surface-acoustic-wave waveguide arranged to cross the optical waveguide; wherein the optical waveguide and the surface-acoustic-wave waveguide are spaced apart from one another in a direction parallel to a plane in which the optical waveguide extends at a starting portion and an ending portion of an operation area of the surface-acoustic-wave waveguide; a first thin film having a refractive index less than that of the optical waveguide is disposed above the optical waveguide and beneath the surface-acoustic-wave waveguide; the first thin film extends over the entire operation area of the surface-acoustic-wave waveguide; and the surface-acoustic-wave waveguide is arranged such that a difference in the speed of sound inside of the surface-acoustic-wave waveguide and the speed of sound outside of the surface-acoustic-wave waveguide is less than or equal to about 1.5%.