Abstract

A nonlinear fibre loop mirror [1, 2] (NFLM) has recently been paid considerable attention as a fast optical switch for various applications. The use of the NFLM for optical signal processing [1-4], for optical pulse shaping [5] and in passively mode locked fibre lasers [6] have been demonstrated. In this paper , we investigate generation of a pulse train relaying on switching of a dual frequency optical beat signal in the NFLM. The idea of pulse train generation through optical beating is based on reshaping the half-periods of the sinusoidal beat signal into well-separated pulses [7]. The reshaping was previously achieved using nonlinear propagation in an optical fibre influenced by "slow" amplification or dispersion decreasing along the fibre length [8], or, alternatively, by exploiting the soliton Raman self-scattering effect [9]. Here, we demonstrate theoretically and experimentally how the nonlinear switching characteristics of the NFLM in conjuction with a dispersion delay line can provide a mechanism for the transformation of a beat signal into a train of well separated transform-limited pulses at multigigabit/s repetition rates.

© 1993 Optical Society of America