Design And Research Of Mode Characteristics Of Submicron Optical Waveguide In Silicon-on-Insulator

In the past several years, silicon photonics has become a hot research topic for the demands of optical telecommunications, optical interconnections, optical computers and optical biosensors. With the powerful support of silicon photonics, electronic circuits and photonic components can be integrated on a single chip to create highly advanced functions in optical information receiving/proceesing and transmission.Silicon-on-Insulator (SOI) is recently widely acceptable and standardable platform of silicon-based photonic-integrated-circuit (PIC), and will find broad applications in the near future. Through the successive optimizations of waveguide size,device design and fabrication process, SOI based PIC devices and modules are playing dominant roles in optical telecommunications, sensors and information processing and destined to become core parts in future optical networks and optical computers.Miniaturization of waveguides is very important for reducing the dimensions of optoelectronics devices and improving the integration of discrete devices. The mode characteristics of SOI submicron rib waveguides are very sensitive to the profile and the dimension of waveguide cross-section.In this paper, we studied and analyzed the single-mode and polarization-independent conditions of rib-waveguides with height and width of less than 500nm, then studied and simulated the influence of the concentration of free-carries on the optical refractive index and absorption of silicon core of submicron waveguides and the influence of outside electric field on the distribution of free-carriers, further we obtimized the optical propagation loss and polarization dependence of both linear waveguides and curved waveguides, and finaly we fabricated some waveguide samples and obtained some experimental results, which are agreeable with the correspeonding simulation values.Our research shows the mode characteristics of sub-micrometer rib-waveguide are different from those of micrometer-sized ones. Conventional analyzing methods such as effective index method have their deficiency, here we have adopted a fast and accurate three-dimensional imaginary beam propagation method (BPM) algorithm, and found there exist a few overlap parameters of waveguide cross-section between single-mode and polarization-independent conditions. Especially, the significantly different single-mode conditions are found between two rib waveguide height values:300nm and 400nm. All the above results are sustainable for constructing high-performance optoelectronic devices based on sub-micrometer nano-wire waveguides.