Hybrid optical integrator based on silicon-on-insulator platform

Abstract

Huh, TaewonA hybrid optical integrator is a recirculating loop that performs oversampling typically for analog input, using the cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA). The modulated input signal changes the gain of the loop through XGM and thus modifies the loop accumulation. This thesis presents hybrid optical integrator for an all-optical analog-to-digital converter based on a silicon photonics platform. The device consists of silicon waveguides of dimension 220 × 500 nm (thick × width) and approximately 5 m optical loop length including fiber length, input and output grating couplers for 1550 nm signal, directional couplers, and external components (SOA, optical isolator and band-pass filter). The silicon photonics devices are designed for fabrication on the SOI wafer using E-Beam lithography. Fiber-optic integrator and hybrid optical integrator are constructed to demonstrate and evaluate a theoretical model for the system. The system is characterized for square waves at Mega-Hertz input frequencies.Experimental results show a sampling period of 28 ns and free spectral range of 35.7 MHz with an optical loop length of five meters, which is in excellent agreement with the theoretical model of the leaky integrator.