Abstract

By exploiting the fast responding nonlinear refractive-index changes in optical fibers, reshaping of ultrashort optical pulses in dual core¹ or dual polarization² fibers has been recently experimentally observed. A correct modeling of the nonlinear switching of short pulses in fiber couplers requires the inclusion of group velocity dispersion. We carried out numerical simulations of the nonlinear propagation in nonlinear directional couplers, birefringent fibers, and fiber rocking rotators. The response time of detectors is longer than the pulse widths of interest. Therefore, we consider the transfer of pulse energies between two output ports, as induced by changes in the input peak power. We find that in the normal dispersion regime, the switching efficiency substantially deteriorates for pulse widths shorter than a certain critical value, which depends on the length of the coupler. Conversely, in the anomalous dispersion regime soiitonic effects may maintain the pulse shape undistorted thus preventing pulse breakup and increasing the sharpness of the switching characteristics.

© 1988 Optical Society of America