The aim of this research is to investigate the performance of a bi-stable device using a single active element and to design a higher order all optical binary delta-sigma modulator (BΔΣM). A Delta sigma modulator has two important components that require enhancement to achieve robust modulation. The first component is the integrator which accumulates the error and at the same time leaks it. Here, the integrator is a single ring laser consisting of a semiconductor optical amplifier (SOA) and a filter to allow the light frequency of interest into the ring. The other component is the bi-stable device (called Schmitt trigger) that switches either ON (1) or OFF (0). There are different novel approaches to developing a bi-stable circuit. First, the coupled two ring lasers where each ring suppresses each other. Second, a novel idea that considered as a bi-stable device with single active element to achieve reduced power and reduce cost. This type of circuit is merged ring lasers with using single SOA. This system is modeled and its bistability hysteretic characteristics is investigated. The first bi-stable device is used to construct an all optical BΔΣM with 1st, 2nd and 3rd -order approaches. It performs better when the SOA bulk device is replaced by multi-quantum well (MQW) SOA.

This dissertation is a contribution toward developing all-optical binary delta sigma modulator (BDSM) [‎27] by changing its bistability to proteretic bistability in order to increase the modulator bandwidth frequency. An innovative delta sigma modulator called proteretic binary delta sigma modulator (PBDSM), which is optically compatible, is investigated theoretically and by modeling and simulation and its bandwidth superiority is proven. The time interval of PBDSM Δt calculation is driven and dynamic performance measure of PBDSM comparing to previous related work is computed, modeled and simulated. Modeling and simulations are based on Matlab-Simulink for ideal environment testing. The basic components of BDSM are the leaky integrator and the bi-stable device. Thus, the focus was on improving the bi-stable device to overcome the bandwidth limitation toward THz modulation frequency in optical domain. Consequently, proteresis bistability was investigated in semi-practical domain, using Matlab-Simulink function, for clear realization of its input-output characteristics and compared with the corresponding hysteresis bistability. The contribution in this research, regarding proteresis bi-stable device design, can be implemented in current technologies, both optical and electrical, of continuous-time delta sigma modulation. Furthermore, the new design showed capability and more flexibility in manipulating its output form and it showed more control on the way of conducting delta sigma modulator error correction.