Silicon-based Integrated Electro-optic Modulator

Modern optical communication technology has been making significant progress toward integration of high-speed, high-capacity all-optical network on-chip. There has been a recent trend to generate, transmit, detect, control and apply light on a high-density integrated chip. The most important part is integration. Silicon has unique advantages as a photonic medium. It is transparent in the range of optical telecommunications wavelengths and has a high index of refraction, which allows for the fabrication of high-index-contrast structures. In addition, the mature Si integrated circuit (complementary metal-oxide semiconductor, CMOS) technology enables the implementation of dense silicon-based integrated optics and electronics on-chip. Compact photonic waveguide devices with superior performance and lower costs are required for large-scale integrated photonic integrated circuits. For this purpose, silicon-on-insulator (SOI) waveguide technology can be employed. Reducing the size of photonic waveguide devices for enabling high-density integration in silicon photonic integrated circuits is the subsequent trend. Researches on transmission characteristics of sub-micron SOI-based optical waveguides and related devices become international academic difficulties and hot issues. Micro-ring resonator is one of the most important devices in integrated optical networks. The micro-ring can perform a variety of functions such as filter, switch, and modulator and so on. It is the basic component in Optical Add/Drop Multiplexer (OADM). Electro-optical modulators and optical switches are key components in all-optical networks. Therefore, the research based on integrated SOI electro-optical modulator is essential for the entire optical communication networks.A simple model of submicron scaled SOI waveguides for modal and polarization analyzing was proposed in this thesis. Characteristics for both rectangular and ridge waveguides were calculated strictly based on 3 Dimensional Full-Vectorial Imaginary distance Beam Propagation Method (3D FV IDBPM). The simulation agrees well with existing experimental data. The scattering matrix and finite-difference time-domain (FDTD) methods were applied to analyze micro-ring resonators. With the analysis of sub-micrometer scaled SOI rib waveguide and micro-ring resonator, a high-quality micro-ring resonator was designed. The free spectral range, extinction ratio,3dB bandwidth and Q are 9.86nm,11.43dB,0.11nm and 14,061 separately, which agrees well with analysis and the simulation data. In order to obtain electro-optic modulator by changing effective refractive index of the waveguide, a PIN diode was employed in the micro-ring resonator to activate plasma dispersion effect in Si material. Modulation extinction ratio is 11.43dB, modulation depth is 92.8% and the wavelength has 0.51nm blue shifted with 1.2V positive bias voltage. The switching rise time is 0.29μs.The research demonstrates that SOI sub-micron ridge waveguides can be applied for optical communication networks with single mode low loss transmission. Integrated electro-optical modulators based on silicon microring resonator are compact, simple structured, which can be maturely processed. It is essential device for modern integrated optical communication networks.