Exploiting high-order phase-shift keying modulation and direct-detection in silicon photonic systems

Abstract

A computational approach to evaluate the bit-error ratio (BER) in silicon photonic systems employing high-order phase-shift keying (PSK) modulation formats is presented. Specifically, the investigated systems contain a silicon based optical interconnect, namely a strip silicon photonic waveguide or a silicon photonic crystal waveguide, and direct-detection receivers suitable to detect PSK and amplitude-shaped PSK signals. The superposition of a PSK signal and complex additive white Gaussian noise passes through the optical interconnect and subsequently through two detection-branch receivers. To model the signal propagation in the silicon optical interconnects we used a modified nonlinear Schrödinger equation, which incorporates all relevant linear and nonlinear optical effects and the mutual interaction between free-carriers and the optical field. Finally, the BER is calculated by applying a frequency-domain approach based on the Karhunen-Loève series expansion method. Our computational studies of the BER reveal that the optical power, type of PSK modulation, waveguide length, and group-velocity are key factors characterizing the system BER, their influence on BER being more significant in a photonic system with larger nonlinearity. In particular, our analysis shows that the system performance is affected to a much larger extent when the signal propagates in the slow-light regime, despite the fact that this regime allows for a significantly reduced length of optical interconnects.

Hybrid/Integrated Silicon Photonics Based on 2D Materials in Optical Communication Nanosystems

“…[14,15] In particular, the strong light confinement enables the dispersion engineering in silicon-on-insulator (SOI) WGs either by changing the transverse size of the WGs or by nanopatterning them. [16][17][18] Furthermore, the SOI WGs possess very large third-order nonlinearities, allowing for the implementation of key active and passive optical functionalities embracing Raman amplification, [19] four-wave mixing (FWM), [20] self-phase modulation, [21] cross-phase modulation, [22] two-photon absorption, [23] and pulse self-steepening. [24] In addition to the SOI WGs, SiO 2 , Si 3 N 4 , GeSi, and Ge-on-Si are also the materials frequently utilized in Si photonics.…”