Bandpass switching based on a nonlinear optical loop mirror and an in-fibre grating reflector

Abstract

The potential of the nonlinear optical loop mirror (NOLM)1 as a device for all optical switching applications has already been demonstrated at multigigabit repetition rates. Self switching of optical pulses within the NOLM requires breaking the loop symmetry to enable the counter propagating pulses to acquire a differential π phase shift. This is achieved with either an asymmetric fused fibre coupler at the input1 or by the inclusion of an asymmetrically located gain or loss element within the loop.2,3 By introducing a frequency selective loss element, non linear switching may be confined to a narrow band of wavelengths or multiple wavelengths. This configuration may have applications in time-wavelength demultiplexing. We demonstrate this technique of bandpass switching in the soliton regime using a fibre-Bragg grating reflector as the wavelength dependent loss.