Patent attributes
An optical coupler for processing radiation is described. The optical coupler comprises a first deep-shallow waveguide and a second deep-shallow waveguide for guiding radiation in a propagation direction. Each of the deep-shallow waveguides is a waveguide comprising a shallow etched portion and an unetched portion having a width substantially constant along the propagation direction. The width of the shallow etched portion is substantially larger than the width of the unetched portion. The shallow etched portion of the first deep-shallow waveguide and the shallow etched portion of the second deep-shallow waveguide are arranged sufficiently close for coupling radiation from the first deep-shallow waveguide to the second deep-shallow waveguide.
