Patent ID: 7027703

Claim:
A method of forming a plurality of optical waveguides leading to at least one free space coupler region comprising the steps of: utilizing a single mask defining monotonically converging mask openings terminating at a interface region with a free space coupler region; forming a plurality of longitudinal optical waveguides as ridge waveguides by etching a groove between adjacent ridge waveguides to form them; and employing said mask to form the grooves with an anisothropic etch to a first depth where the cross-sectional width of a groove between adjacent ridge waveguides along their longitudinal length monotonically decreases up to the interface region and terminating at the interface region with the free space coupler region, followed by etching with the same mask with an isothropic etch to a second depth where the depth of a groove between adjacent ridge waveguides along their longitudinal length monotonically decreases in depth up to the interface region and terminating at the interface region with the free space coupler region.