NONLINEAR SAGNAC INTERFEROMETER SWITCH AND ITS APPLICATIONS

Ultrafast all-optical switching based on the optical Kerr effect in a Sagnac interferometer which consists of a dichroic polarization-maintaining fiber coupler and a dispersion-shifted polarization-maintaining fiber loop is reported. This nonlinear Sagnac interferometer switch has the advantage of high stability originating from completely balanced interfering arms. In addition, because we used dispersion-shifted fibers, which provide group velocity matching between the input signal and the control pulse, increases in switching power and switching time were prevented. Moreover, polarization fluctuation was completely suppressed due to the all-polarization maintaining fiber configuration. The required switching power for complete switching was measured to be 1.8 W for a 200 m long fiber, and was in good agreement with the theoretical value for cases of parallel polarization and no walkoff. All-optical time division demultiplexing and logic operations, including inversion and AND operation, using the nonlinear Sagnac interferometer switch were successfully demonstrated at 5 Gb/s. Its possible use as XOR and XORBAR gates was also demonstrated at 3.8 Gb/s.