A Passive All-Optical Device for 2R Regeneration Based on the Cascade of Two High-Speed Saturable Absorbers

We discuss the design and realization of a passive all-optical device for 2R regeneration based on a dual-stage of high-speed microcavity saturable absorbers, one for noise reduction of digital zeros (SA-0), and the other for noise reduction of digital ones (SA-1). The numerical and experimental results showed that by using a simple combination of SA-0 and SA-1 devices, one can obtain an intensity transfer function with a large extinction ratio improvement of low power levels and a strongly nonlinear response reducing the noise of high power levels. The amplitude and phase characterization of a 40-GHz signal transmitted by this device, obtained by frequency-resolved optical gating measurements, reveals the intensity-dependant pulse-compression effect and the low chirp introduced by this device.