Low-loss and broadband 2 x 2 silicon thermo-optic Mach-Zehnder switch with bent directional couplers

A low-loss and broadband silicon thermo-optic switch is proposed and demonstrated experimentally by using a Mach-Zehnder Interferometer with 2 x 2 3 dB power splitters based on bent directional couplers (DCs). The bent DCs are introduced here to replace the traditional 2 x 2 3 dB power splitters based on multimode interferometers or straight DCs, so that one achieves a coupling ratio of similar to 50%: 50%, as well as low excess loss over a broadband. The demonstrated Mach-Zehnder switch (MZS) has a similar to 140 nm bandwidth for an excess loss of <1 dB and an extinction ratio of >20 dB. The present MZS also shows excellent reproducibility and good fabrication tolerance, which makes it promising for realizing N x N optical switches. (C) 2016 Optical Society of America