Cascaded Multimode Interference-Based 1x2 Light Splitter for Photonic Integrated Circuits

摘要

A new light splitter based on multimode interference is proposed and demonstrated. Its length is shorter that standard MMI 1x2 splitter for most practical waveguide platforms/dimensions in the InP material system. The difference in length becomes drastic for higher output waveguide spacings and lower access waveguide widths, and the cascaded splitter can be as much as 50% shorter. Furthermore, the cascaded splitter is about 50% narrower, therefore reducing the overall device size by more than 50%. This splitter can also be used to replace standard splitter-bend combinations on PICs, while having comparable length and lower scattering losses. Low losses are possible due to the fact that cascaded MMI splitter can be fabricated using selective wet crystalographic etching, as opposed to reactive ion etching used to create curved waveguides. These characteristics make the cascaded splitter suitable for realization of Mach Zehnder and Michelson interferometers for low cost wavelength converters and modulators, as well as for devices using heterodyne detection. Simulations show and preliminary measurements confirm that this device has large optical bandwidth (1 dB over 80 nm) and low inherent loss of 0.37dB.