| Optical nanostructured composites are manufactured devices composed of two or more constituent materials with characteristic size scales smaller than the optical wavelength. These composites can be engineered to provide the desired optical properties, such as birefringence, dispersion, enhanced nonlinearity, and so forth. As semiconductor fabrication technology advances, there is an increasing interest in using semiconductor heterostructure as a platform for nanostructured composite optical components to realize integrated optoelectronics. This dissertation describes the development of nanofabrication techniques to realize several GaAs- and GaAs/AlGaAs-based nanostructured elements for free-space applications, including two-dimensional three material photonic crystal nanocavity for optical filtering, subwavelength form birefringent structures for phase retardation, inhomogeneous media for polarization control, and subwavelength computer generated holograms for spot array generation. The fabrication techniques are developed using electron-beam lithography and chemically assisted ion beam etching, which provide high-aspect-ratio profiles for these elements as well as for large-area integrated nanophotonic circuits. The characterizations of the fabricated devices are described in detail, and we find the theoretical prediction and experiment measurement are in good agreement. |
