Carrier-depletion-based optical modulator integrated in a lateral structure in a SOI waveguide

Abstract

A high speed and low loss silicon optical modulator based on carrier depletion has been made. It is based on carrier depletion and consists of a p-doped slit embedded in the intrinsic region of a lateral pin diode. This device has advantages such as a low capacitance and low optical insertion loss. Experimental results are reported. Using a Mach-Zehnder interferometer with 4 mm-long phase shifter, contrast ratio of 14 dB has been obtained with insertion loss of 5 dB. A 3 dB-bandwidth of 10 GHz has been measured at λ = 1.55μm. Driving electrical power is evaluated. For a 5 mm-long active region, driving power is 100 mW at a frequency of 10 GHz. A large contribution of the dissipated power comes from the 50 Ω load at the end of the device. By integrating the modulator and its driver on CMOS chip, the load value could be varied and driving power could be reduced to a few tens of mW.