Numerical Study of Optical Delay in Semiconductor Multilayer Distributed Bragg Reflector and Tunable Microcavity Structures

The Air Force has a growing need for the greater bandwidth, speed, and flexibility offered by optical communication links. Future space systems and airborne platforms will most likely use optical signals for efficient power transmission and to minimize the possibility of spoofing and eavesdropping. Tunable optical delays play an important role in the implementation of free space optical communication links. The primary challenge in implementing these systems is the active maintenance of coherent wave fronts across the system's optical aperture. For space applications, this aperture may be hundreds of meters in diameter. Spatial segmentation of a large aperture into smaller elements is one approach that can be used to solve the problem of coherent waveform maintenance. In this research I explore three methods of achieving electrically tunable optical delay in a semiconductor structure. My first approach entails the use of multiple quantum wells inserted within the high index layers of a distributed Bragg reflector (DBR) to produce tunable optical delay when a transverse electric field is applied across the entire DBR. The second approach uses a cantilever mounted on top of a DBR structure. The cantilever is also a DBR and is used to vary the thickness of an air gap within the structure. A third approach relies on changing the angle of incidence of light on a DBR structure to produce a delay.