title: Ultracompact directional couplers realized in InP by utilizing feature size dependent etching.
abstract: We present the design, fabrication, and measurement of an ultracompact directional coupler in InP/InGaAsP/InP. By utilizing the lag effect in the dry etching process, in one etch step, deeply etched asymmetric waveguides with a shallow groove in between are fabricated. This special property enhances the coupling efficiency for the directional coupler and thus makes the device ultracompact. We demonstrate directional couplers as short as 55 microm, which is only 1/30th the length of the conventional design.
authors.affiliation: Joint Research Center of Photonics of the Royal Institute of Technology, Kista, Sweden.
authors.forename: Yaocheng
authors.initials: Y
authors.lastname: Shi
authors.forename: Sailing
authors.initials: S
authors.lastname: He
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Anand