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

In this paper, we experimentally measure the temporal evolution of amplitud e restoration and thresholding in an all-optical regenerative memory. The m emory architecture comprises two coupled all-optical switching gates and di fferent 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 res ponse of these nonlinear interferometers provides the required square top t ransmission 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 int o the memory and record the temporal evolution of the pulses with a fast re al-time digitizing oscilloscope. Complete amplitude restoration of the puls es occurs after similar to 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.