A leaky waveguide all-optical analog-to-digital converter

In this thesis we describe a novel all-optical analog-to-digital converter (AOADC) based on a leaky waveguide deflector. The principle of the spatial sampling AOADC is to convert an electrical signal to its corresponding optical deflection angle and then sample and quantize this angle in the spatial domain, instead of the amplitude domain. This AOADC is designed for broadband digital receivers working at frequencies above 20 GHz (a minimum 40 GS/s sampling rate) and provides a resolution higher than 6 bits. An original design based on GRISM (Grating and pRISM) is investigated for a high-resolution ADC implementation; and its challenges have been identified. The investigation provides a general model of spatial sampling AOADCs and highlights their advantages of immunity to optical intensity fluctuation. Later we proposed an AOADC that employs a leaky waveguide structure that is different from any other optical ADC. The AOADC consists of a sampler based on a mode-locked laser and a leaky waveguide deflector driven by traveling wave electrodes, a quantizer based on an integrated optical collector array and broadband photodetectors. These components provide the AOADC with a higher deflection angle and angular resolution resulting in high bit resolution without consuming significant power. The quantization of the deflection angle is done by a simple spatial quantizer that digitizes as well as encodes the signal simultaneously. A detailed design of the E-O deflector and the spatial quantizer has been analyzed and simulated; and some preliminary tests have been conducted. This thesis summarizes our contributions in designing and modeling this novel spatial sampling AOADC.