R. Giller

The turbo-switch - a novel technique to increase the high-speed response of SOAs for wavelength conversion

A new scheme for wavelength conversion employing two semiconductor optical amplifiers (SOAs) results in substantially higher speed and reduced data-patterning effects. Error-free conversion at 170.4 Gbit/s is demonstrated.

Analysis of the dimensional dependence of semiconductor optical amplifier recovery speeds

We investigate the dependence of the speed of recovery of optically excited semiconductor optical amplifiers (SOAs) on the active region dimensions. We use a picosecond pump-probe arrangement to experimentally measure and compare the gain and phase dynamics of four SOAs with varying active region dimensions. A sophisticated time domain SOA model incorporating amplified spontaneous emission (ASE) agrees well with the measurements and shows that, in the absence of a continuous wave (CW) beam, the ASE plays a similar role to such a holding beam. The experimental results are shown to be consistent with a recovery rate which is inversely proportional to the optical area. A significant speed increase is predicted for an appropriate choice of active region dimensions.

Gain and phase recovery of optically excited semiconductor optical amplifiers

An investigation of the recovery dynamics of semiconductor optical amplifiers (SOAs) explains why the ultrafast component of the gain recovery is largely absent in the phase response. The time-resolved gain and phase dynamics of a bulk GaInAs SOA are measured using a pump-probe technique and differences between the gain and phase recoveries are highlighted and explained using Kramers-Kronig analysis. These have important implications for optical signal processing.

Pattern Effect Mitigation in the Turbo-Switch

By measuring cross-gain modulation in a turbo-switch, we demonstrate that appropriate control of the optical power in this high-speed all-optical switch results in greatly reduced dependence on the input data pattern. We further show that the non-linear patterning may even be reversed for high internal powers.

SOAs for All-Optical Switching-Techniques for Increasing the Speed

This paper reviews some of the most recent methods for increasing the speed of operation of all-optical switches based on semiconductor optical amplifiers (SOAs). We concentrate on two approaches; namely, methods to utilise the high-frequency tail of the nonlinear optical response of SOAs, and ways to reduce their gain recovery time.

Dimensional Dependence of Semiconductor Optical Amplifier Recovery Speeds

We investigate the dependence of the high-speed performance of bulk GalnAs semiconductor optical amplifiers (SOAs) on the dimensions of the active region. Corroborating experimental and modelling results predict a two-fold speed increase for optimised dimensions.

Dynamics of optically excited semiconductor optical amplifiers

For the first time, an investigation of the recovery dynamics of semiconductor optical amplifiers explains why the ultrafast component of the gain recovery is largely absent in the phase response. This has important implications for signal processing.

Error-free All-optical 40Gb/s Wavelength Conversion by Nonlinear Polarisation Rotation using SOA-based Turbo-switch

We demonstrate error-free all-optical 40Gb/s wavelength conversion using nonlinear polarisation rotation in semiconductor optical amplifiers (SOAs). The high speed of the device is achieved by incorporating an SOA-based turbo-switch. The switching energy is 10fJ/pulse.