Abstract
Discussed are the light transmission and their characteristics in a leaky step-index planar waveguide. In this waveguiding structure, an input guided mode will couple to continuous radiation modes, located in the leaky section. The major contribution of this thesis is to introduce a new concept - the leaky bound mode - to analyze the previous problem. The methodology is as follows. We are visionally incident a light ray from one side of the cladding to the leaky waveguide. If we can obtain extreme reflection, this condition corresponds to a new kind of bound modes, namely the leaky bound mode. This new method is straightforward and simple. Knowing the familiar light transmission and reflection by a multilayered structure are sufficient while this new method is actually originated from the evanescent field excitation, proposed by our predecessors. In this thesis, we also investigate the light throughput in leaky waveguides. Two methods based on the leaky bound mode and a ray-optic approach are presented and compared. Excellent agreement between the two methods is found. Our method is very useful and efficient in analyzing multilayered structures and no numerical technique, e.g., finite element method, is required.