A Novel M-Z Modulator Based on Photonic Crystal and Nanowire Waveguide

A novel photonic crystal-based Mach-Zehnder electro-optic modulator is proposed. The modulator is mainly composed of silicon-based photonic crystal slab waveguide, nanowire waveguides and a photonic crystal multimode interference 1 × 2 couplers (MMI). Two phase modulation arms of the modulator are formed by photonic crystal slab waveguides. One arm act as an optical phase shifter. To achieve this, two electrodes, are placed parallel to the left and right sides of the photonic crystal slab waveguide to apply a reverse bias to the arm. The photonic crystal multimode interference 1 × 2 couplers act as the splitter and combiner of the modulator and connects these components through nanowire waveguides. The proposed MZI starts with a single mode rib waveguide which splits into two symmetric branches by means of a photonic crystal multimode interference 1 × 2 coupler (MMI). Hence, the two arms become parallels and are surrounded by a proper PhC structure to increase the propagating wave confinement in the waveguide core. At the output, light beams interfere between each other by means of a photonic crystal multimode interference 1 × 2 coupler (MMI). Two beams superimposed at the combiner when there is no modulation voltage. That is, the output light intensity is approximately equal to the input light intensity, the modulator is in the “on” state. When the modulation voltage is applied across the interference arm. The output light intensity is approximately equal to 0, the modulator is in the “off” state. The advantage of using photonic crystal multimode interference couplers as the splitter and combiner is that it not only can greatly reduce the size of the device, but also reduce the loss. The device is made of silicon with low price and mature technology. The simulation results show that the length of the proposed photonic crystal-based Mach-Zehnder electro-optic modulator is 40 μm, and the extinction ratios is 12.4 dB.