UW ME MEMS & EE Electromagnetic and Remote Sensing Joint SEMINAR

1. UW ME MEMS & EE Electromagnetic and Remote Sensing Joint SEMINAR TITLE: Semiconductor dielectric waveguides, basic theory and design principle SPEARKER: Hung-Wen Chang and Tuo-Lun Wu National Sun Yat-Sen University, Institute of Electro-Optical Engr, Kaohsiung , Taiwan DATE: OCT 14, 3:00PM PLACE: ME 134 ABSTRACT: Dielectric waveguides are important passive devices in optical communication systems. The dielectric ridge waveguide is the basic building block for integrated optics. By controlling the shape (width and depth, etc) of the ridge structure, one can also control the optical field concentration, propagation constant and even the polarization. Unlike the microwave waveguide, the field distribution is very complex and it is not confined entirely within the core as in the case of dielectric waveguides. Thus it is very hard to analyze and to design optical circuits. In this talk we will cover various optical devices made of passive dielectric waveguides such as the loss ARROW waveguide, Y-branch beam splitter/combiner, directional coupler, polarization converter, polarizer and optical filters made of arrayed waveguide grating (AWG) and micro-ring cavities. We will discuss the use of both scalar vectored theory and approximation method for obtaining effective mode index of the ridged waveguides. Various waveguide design concers including available materials index ranges, waveguide mode field distribution, mode field confinement (spot size, isolation), mode polarization (critical for active devices) and waveguide dispersion characteristics will be addressed. Example includes the complete design of a 64 channel AWG optical mask and optical circuit layout. MTL ERSL

2. UW ME MEMS & EE Electromagnetic and Remote Sensing Joint SEMINAR TITLE: Modal analysis of complex dielectric waveguides by rigorous transverse mode integral equation formulation SPEARKER: Hung-Wen Chang and Tuo-Lun Wu National Sun Yat-Sen University, Institute of Electro-Optical Engr, Kaohsiung , Taiwan DATE: OCT 13, 2:30PM PLACE: EE Room 303 ABSTRACT: Planar light wave circuits (PLC) holds great promise for the future of optical communication systems. There are many complex integrated photonic waveguide structures that are difficult for commercial software packages based on BPM, FD-TD and mode-matching method. While no single method will be able to address these problems independently, the coupled transverse-mode integral-equation method that we have been developing provides reliable analysis of general rectangular-like dielectric waveguides. The problem on hand is first separated into (or stair-case approximated by) slices of layered structures. Fields in each slice can be expanded by both TE to y and TM to y (1-D) layered waveguide modes within that particular slice. The expansion coefficient vectors are closely related to the y–component electric and magnetic fields on the slice boundaries. It can be shown these interfacial tangential fields obey a coupled transverse mode integral equation (CTMIE). These coupled integral equations are then converted into a homogeneous matrix equation via orthogonal projection. The nontrivial solutions for the matrix equation are used to construct the full-wave modes field distribution as well as the mode propagation constant for the structure under investigation. Among all the methods mentioned above CTMIE formulation is the most rigorous and most analytical in nature. Even though the CTMIE formulation is somewhat complex, it requires the least computational resources. This technique can be extended to study waveguides with more complex structures and can provide, up to eight accurate digits. MTL ERSL