Contents 1. Introduction
Fundamental bottleneck bandwidth issue of metallic interconnects within the electronic chips (due to the interconnect delay with further scaling) limits the data rate capability of the existing electronic modulator [1]. Direct modulation in optical regime controlled by the external information carrying electrical signal removes this limitation due to high bandwidth operation (in THz) of the optical signal. In the past few decades, researchers have put significant efforts to achieve efficient optical modulation, especially for high-speed communication. Among the various reported work, Si-based optical modulator has attracted much attention due to its fabrication compatibility with preexisting CMOS platform [2]. Phase modulation of optical signal caused by change in material index (due to the plasma dispersion effect in p-n junction embedded structure is widely studied [3]. Injection type p-n junction based modulator have shown its potential to achieve truly high modulation efficiency () but at the cost of poorer speed performance (due to high diffusion capacitance and carrier lifetime), whereas depletion mode of operation is preferred when high data rate is our primary objective (due to low RC time constant) [4].
