Square pulse amplification using nonlinear loop mirror incorporating saturable gain

A nonlinear fibre loop mirror is described that comprises an 8.8 km length of dispersion shifted fibre and an erbium doped fibre amplifier. The low calculated switching powers ( approximately milliwatts peak) afforded by the high gain ( approximately 20 dB) and long loop length have been confirmed by measurements of the square pulse response. As experimental and theoretical study of the effect of gain saturation on the device characteristics has also been conducted.