The energy-limiting characteristics of a polarization-maintaining Sagnac interferometer with an intraloop compressively strained quantum-well saturable absorber

An experimental demonstration of an energy limiter for short pulses at 1550 nm is reported. The limiter is based on an optical fiber Sagnac loop with an intraloop dichroic saturable absorber based on an InGaAsP-based waveguide with compressively strained multiple quantum wells. The saturable absorber is placed asymmetrically in the loop and is used as a Kerr-like nonlinear phase shifter. The device is operated in a novel dual polarization scheme, which offers some unique advantages. Excellent limiting for noise reduction purposes is demonstrated with the device.