Optically buffered waveguide modulator

Claim 1

An infrared electro-optic modulator comprising: an optical waveguide slab having substantially parallel top and bottom surfaces, a predetermined waveguide index of refraction in a predetermined optical wavelength range that determines a waveguide phase velocity of light in said wavelength range, a predetermined waveguide dielectric constant, and a predetermined waveguide thickness along an axis perpendicular to said top and bottom surfaces; a top optical buffer layer adjacent said top surface, having a buffer index of refraction in said predetermined optical wavelength range that is less than said waveguide index of refraction, a predetermined buffer layer dielectric constant, and a predetermined buffer thickness; a top electrode, having a predetermined electrode width along a transverse direction perpendicular to said axis and a predetermined electrode length along a longitudinal direction perpendicular to both said axis and said transverse direction, disposed on said top optical buffer layer; and a bottom electrode disposed below said optical waveguide slab, characterized in that; a bottom optical buffer layer is formed adjacent said bottom surface and disposed above said bottom electrode, also having said buffer index of refraction, said buffer layer dielectric constant and said buffer thickness; and said waveguide thickness and said buffer thickness of said top and bottom optical buffer layers combine with said top and bottom electrodes to form a microwave transmission line having a predetermined phase velocity for traveling wave microwave signals that is substantially equal to said predetermined waveguide phase velocity of light.