Simulation of optical switches using the Monte Carlo method

We have calculated the response of a sub-micron GaAs MSM optical switch to light pulses of wavelengths 799 nm, 734 nm and 633 nm. It was found that the response of the total current (including displacement) at 799 nm was characterized by an approximately exponentially decaying current, whilst at 633 nm the current first rose to a peak before falling exponentially again. For the intermediate wavelength, the response was broadly exponential, though interrupted by a peak corresponding to the peak electron photocurrent. The response of the electron photocurrent component was characterized by an initial rapid rise to a peak after about 2 picoseconds, followed by an exponential decay. The initial pulse reached its peak later and was broader for the higher energy radiation, the delayed response being explained by the larger population of electrons raised to the lower symmetry heavier bands at the higher creation energies. The hole response was largely unaffected by the energy of the incident radiation