Monolithic Semiconductor Waveguide Device Concept for Picosecond Pulse Amplification, Isolation, and Spectral Shaping

In this paper, a waveguide device concept, named IRIS, is presented. The device consists of a monolithic array of concatenated semiconductor optical amplifiers and saturable absorbers. We have theoretically investigated picosecond pulse transmission through these devices. The parameters used in the simulation are representative for InP-InGaAsP bulk gain material, operating in the 1550-nm region. Operated as an optical amplifier for picosecond pulses, the simulation results show increased pulse peak amplification and decreased temporal broadening of the pulses for the IRIS devices as compared to a semiconductor optical amplifier of equivalent length. Used as a nonlinear element to increase the optical bandwidth of a picosecond pulse, the spectra obtained with IRIS devices show an increased broadening and smoothness as compared to a semiconductor optical amplifier. Finally the feasibility for using the IRIS device as an optical isolator is shown. It is operated in a regime where the device is transparent for a picosecond pulse train, while it is absorbent for lower power reflections.