A Study On Photonic Crystal Waveguide Based Mach-Zehnder-Type All-Optical Switch

With the progress in wavelength division multiplexing and time division multiplexing technologies, efficiently handling a large amount of data at network nodes has become an important issue. Electrical switch is inferior due to the electronic speed bottleneck. As a result, all optical switch and all optical signal processing are attracting more and more attention and becoming a hot-debated issue. All-optical switch is critical device in ultra-high-speed all-optical network due to its ultrafast signal processing ability (up to Tb/s). In this paper, we proposed a novel two-dimensional photonic crystal waveguide based Mach-Zehnder-type ultrafast all-optical switch using Quantum Dot Semiconductor Optical Amplifier (QD-SOA). This scheme possesses the practical advantages of low power consumption, low latency, high speed data processing ability, and integration potential.The main contest of this paper is listed as follows:(1) Three-energy-state rate equations including wetting layer state, excited state, ground state for QD-SOA is established together with propagation equations for optical pulses in which dispersion is neglected. The method for simulation of our work is discussed;(2) The output signal properties, gain saturation properties, carrier distribution and their recovery properties, gain recovery properties are analyzed based on three-energy-state rate equations and propagation equations for optical pulses. The higher is the confinement factor, the less is the 3dB saturation power for QD-SOA;(3) The contrast ratio of our all optical switch is investigated by varying the peak power of the pump pulse, signal pulse, inject current and the length of the QD-SOA. It is indicated that the contrast ratio of the switch is significantly enhanced by photonic crystal waveguide;(4) The material, the structure and the fabrication processes of the proposed all optical switch is proposed.