Temporal evolution of amplitude restoration and thresholding in an all-optical regenerative memory

Abstract

In this paper, we experimentally measure the temporal evolution of amplitude restoration and thresholding in an all-optical regenerative memory. The memory architecture comprises two coupled all-optical switching gates and different wavelength optical pulses are used for clock and data sources. The all-optical gates are nonlinear interferometers incorporating semiconductor optical amplifiers as the nonlinear optical material. The concatenated response of these nonlinear interferometers provides the required square top transmission function that allows the stored optical pulses to be equalized in amplitude. The edge of the transmission function forms the threshold for pulse storage in the memory. We input a variable amplitude data packet into the memory and record the temporal evolution of the pulses with a fast real-time digitizing oscilloscope. Complete amplitude restoration of the pulses occurs after ∼5 circulations of the optical fibre memory loop. This measurement is in good agreement with the theoretical prediction and indicates that the square top transmission response could also be achieved for data ‚on the fly’ with a linear concatenation of only a few all-optical switching gates.