Ultrafast optical switching in a nonlinear loop mirror (NOLM) constructed from dispersion decreasing fiber (DDF)

The performance of a nonlinear optical loop mirror (NOLM) device constructed with a dispersion decreasing fiber (DDF) operating in the soliton and quasi-soliton regime is investigated numerically. Results showed that the soliton regime presents best behavior when compared with the quasi-soliton regime. In the quasi-soliton regime, the transmitted pulse presents strong shaping effect, (compression). However in the soliton regime, the transmitted pulses present fewer fluctuations in the time duration with pump power. Our simulations considering four different profiles, linear, hyperbolic, exponential and Gaussian conclude that, in average, the hyperbolic profile gives the lowest pump power for the first, second and third transmission peaks of transmission compared with the other profiles. The Gaussian profile presents the worse behavior. It was also observed that with a proper choice of the dispersion profile we could have a transmitted pulse with no distortion in the soliton regime. For the quasi-soliton regime, strong compression was observed.