Tailoring of low-temperature-grown gallium arsenide for all-optical device applications

Future communications and computing systems will require advanced capabilities to handle the increasing requirements for ever-faster and higher-bandwidth operation. To move beyond the system limits imposed by electronic components, researchers are investigating the use of all-optical components for ultrafast operations such as switching, and time-division multiplexing and demultiplexing. The requirement for operating times to be significantly faster than those possible with electronics means that the optical components must operate in the picosecond or sub-picosecond range. We can also project further desirable features of this new ultrafast technology. All-optical devices require a material with an optical nonlinearity so that one optical beam can control another. Compact devices will require large nonlinearities, so that switching can be effected at modest power levels. Another desirable feature relates to the integrability of these ultrafast switching components with other optoelectronic components such as lasers and detectors. This clearly favors a III-V semiconductor based device. Although normal III-V semiconductor materials exhibit large optical nonlinearities near the band edge, they have a relatively slow (nanosecond) response due to the slow recombination times for the optically-excited carriers. This paper reports our new findings on how the nonlinear optical properties of low temperature-grown GaAs can be tailored via growth and subsequent annealing conditions to yield a material with the desired characteristics for a specific ultrafast device.