Ion implantation fabrication of gallium arsenide integrated optical components

Proton implantation of n-type GaAs produces compensation of the free carriers in the implanted region. This compensation leads to a change in the refractive index of the implanted layer, making it suitable for optical waveguiding. Based upon the solid-state theories criteria presented, low-loss single-mode optical waveguides were developed. The results of this work include cutoff conditions and a relation for propagation loss versus substitute doping for both planar and channel waveguides at three particular wavelengths of interest. The design techniques are applicable for obtaining waveguide designs for the entire infrared range of 1 to 12 μm. These waveguides can then be used to form the integrated optical building block in a variety of optoelectronic device applications, such as the parallel-channel directional coupler analyzed as part of this work. Excellent agreement between theory and experiment was obtained. Results indicate that optimum optical and electrical properties can be obtained in planar and channel waveguides through use of the design and analysis techniques developed, and through careful control of implantation and substrate parameters