Abstract

Nonlinear Fabry-Perot étalons have been studied vigorously in recent years as potential all-optical decision-making elements. Fundamental physical and engineering tradeoffs have thus far prevented their use in real-world systems. Bistable devices can be cascaded at megahertz rates but require strong holding powers and fail to demonstrate useful gain for subnanosecond pulses. Two-wavelength logic-gate étalons can switch in picoseconds with picojoule energies but have thus far proved difficult to cascade. In this talk we propose a paired semiconductor étalon scheme that attempts to solve these problems, and we present the results of computer simulations of the device concept. In the envisioned architecture a two-wavelength NOR-gate étalon is operated in series with an "upconverter" étalon to allow cascadable operation on a picosecond timescale. The paired device is predicted to achieve a fan-out of at least 2 and good overall contrast, requiring about 75 pj to perform a single logic operation/upconversion. Related simulations indicate that the NOR-gate étalon itself requires a minimum of 28 pJ to achieve the same contrast and fan-out. Thus the price for cascadability is basically a threefold increase in input energy over the NOR-gate alone. The energy requirement might be reduced through the use of multiple-quantum-well materials. The computer simulations of the device behavior are based on a realistic model for the carrier-density-dependent optical nonlinearities of bulk GaAs.

© 1990 Optical Society of America