High-efficiency strip-loaded waveguide based silicon Mach-Zehnder modulator with vertical p-n junction phase shifter

We demonstrate a silicon Mach-Zehnder modulator (MZM) based on hydrogenated amorphous silicon (a-Si: H) strip-loaded waveguides on a silicon on insulator (SOI) platform, which can be fabricated by using a complementary metal-oxide semiconductor (CMOS) compatible process without half etching of the SOI layer. Constructing a vertical p-n junction in a flat etchless SOI layer provides superior controllability and uniformity of carrier profiles. Moreover, the waveguide structure based on a thin a-Si: H strip line can be fabricated easily and precisely. Thanks to a large overlap between the depletion region and optical field in the SOI layer with a vertical p-n junction, the MZM provides 0.80-to 1.86-Vcm modulation efficiency and a 12.1-to 16.9-dBV loss-efficiency product, besides guaranteeing a 3-dB bandwidth of about 17 GHz and 28-Gbps high-speed operation. The aVpL is considerably lower than that of conventional high-speed modulators. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement