We present a wavelength-tunable ultrafast optical switch using a nonlinear optical loop mirror (NOLM), which has a low walk-off characteristic between the signal pulse and the control pulse thanks to the use of a dispersion-flattened highly nonlinear fiber. A 400-fs switching speed and an extinction ratio of >32 dB were obtained from 1528 to 1565 nm. The NOLM was applied to the 320 to 40 Gbaud demultiplexing of DQPSK Nyquist pulse signals, and error-free operation was achieved over the entire C-band.
- Highly nonlinear fiber
- Nonlinear optical loop mirror
- Optical switch
- Optical time-division multiplexed transmission