Ultra-compact high speed silicon modulators for photonic integrated circuits

The main scope of this work is to simulate, design and characterize high speed optical FP modulator based on the SOI platform with a high modulation depth and low power consumption. The modulator structure consists of a 1D PhC microcavity resonator integrated in a single mode nanoscale silicon rib waveguide acting as a FP resonator. Optical modulation is achieved through exploiting the PDE in the silicon cavity by an embedded p+-i-n+ junction lateral to the cavity. Chapter 2 introduces the waveguide and photonic crystals theory where analytically the light propagation within waveguides and 1D PhC structures is discussed. In this chapter, an optical simulation model based on the finite-difference time-domain (FDTD) method is utilized to calculate the behavior of the propagated light in nano-cavities numerically. Chapter 3 explains the electro-optical effects in semiconductors including the necessary mechanisms that may be used to modulate light in semiconductors. Therefore the carrier mobility and recombination processes involved are discussed. An electrical simulation module was used to calculate the static and dynamic states for different active devices. The carrier dynamic model and related required parameters in the electrical simulation model will be explained briefly. Chapter 4 includes the simulation, the design and the optical characterization of different FP resonator structures based on 1D PhC microcavities to meet the optimum resonance requirements. This chapter focuses on characterizing the optical properties of different resonator geometries as well as different waveguide types and material profiles. The results achieved in this chapter were considered in the design of a new generation of electro-optical modulator devices. In chapter 5, the principle of an electro-optical modulator device is introduced. This includes presenting the theoretical and experimental results of the spectral resonator characteristics, free-carrier dynamics and optical modulation capabilities of the electro-optical modulator structures. Improving the performance of a modulator based on a homogeneous diode by iterating the intrinsic region width of the p+-i-n+ diode is presented. A novel node-matched diode (NMD) geometry to build highly efficient modulators and a comparison with a modulator based on a homogeneous diode will also be introduced in this chapter. Chapter 6 includes the thesis conclusions and highlights the key points of this work. Suggestive remarks for future research to build up photonic integrated circuits PICs are given in this chapter.