Slowing and switching of light in semiconductor quantum wells

After light became a part of the telecommunication system, the manipulation of light, especially the control of the speed of light, became a focus of research. By using the different approaches of the interaction between light and matter, there have been many successful attempts to slow down the speed of light, even to several meters per second. In the first part of my thesis, I studied pulse propagation in absorptive media (GaAs/AlGaAs multiple quantum well structures-MQWs) to gain insight into the linear interaction between matter and light. Systematic and fundamental measurements of pulse propagation in GaAs/AlGaAs multiple quantum well structures will be presented. These measurements are simulated by treating MQWs as a slab. These measurements and simulations will be compared while using a newly introduced general formalism.

In the second part of my thesis, I will present another aspect of manipulating light: all-optical switching. Eric Gansen demonstrated all-optical switching in GaAs/AlGaAs MQWs at cryogenic temperatures. I will demonstrate that the same design of all-optical switch, which is based on polarized virtual carriers, can work without any serious loss of performance at near-room temperatures.

Another material used in all-optical switches is Bragg-spaced-quantum-well structures (BSQWs) which are grown by molecular beam epitaxy. The growth of BSQW is challenging because of the associated unusually long growth times. In the last part of this dissertation, I will discuss the challenges involved in MBE growth of 210 period long GaAs/InGaAs BSQWs. By presenting basic characterization measurements of the successful and unsuccessful attempts of BSQW growths, I will demonstrate the challenges of BSQW growth and how they can be addressed.