Aluminum Gallium Arsenide Waveguide Switching Devices: Experimental Techniques and Theoretical Analysis

The objectives of this research were (1) to develop experimental techniques to form the technical basis for the realization of successful waveguide switching devices, and (2) to theoretically analyze a new nonlinear asymmetric directional coupler. A new planar waveguide mode index measurement technique was developed. It is simple to set up, easy to use, and is noncontacting and nondestructive. It can also be used to measure the mode index of buried waveguides which are difficult to measure by conventional methods. A new waveguide alignment technique was developed, which uses Lloyd's mirror fringes to align a waveguide parallel to a line light source. The angular sensitivity of the interferometric technique provides an angular magnification of 800. Conventional waveguide fabrication and characterization techniques were also developed in this research. These include cleave-and-break, etching, end-fire coupling, and Fabry-Perot loss measurement techniques. The analysis of a nonlinear asymmetric directional coupler consisting of a pair of linear and nonlinear waveguides for all-optical switching was the major thrust of the theoretical analysis. Applications of Jacobian elliptic functions for the solutions of nonlinear waveguides were also studied. Similarities between linear and nonlinear dispersion equations were compared. Spurious roots were found in the most-used nonlinear dispersion equation, and a new format for the nonlinear waveguide dispersion equation was derived. A new numerical approach: the mode mixing method and the overlap integral were used for the analysis of nonlinear couplers. The combination of the two numerical methods simplified the analysis for nonlinear couplers and improved the physical understanding of the directional coupler. It was shown that if the coupler was set up to be synchronous, a high switching contrast, 20 dB, was obtained at lower power by choosing the nonlinear waveguide as the input guide. However, if the coupler was initially set up to be asynchronous, it could not be used as an all-optical switch. A new waveguide beam steering device that has a steering angle of 16^circ was also developed. This device, consisting of a pair of asynchronous waveguides, should result in a simpler implementation for optical sensors, beam steering devices, and optical switching devices.