Optical directional couplers with weighted coupling

Abstract

We have fabricated optical directional couplers using titanium‐diffused waveguides for which the coupling strength is carefully weighted along the device. With a Hamming function weighting, −25‐dB transfer response sidelobes have been obtained, a 17‐dB reduction over the uniform coupling case. Sidelobe reduction results in a significant increase in the performance of directional coupler filters and switches.