We demonstrate a nonadiabatic microfiber sensor with a taper diameter of few micrometers. The modal interference caused by the abrupt taper results in a sinusoidal spectral response. The wavelength shift arising because of the changes in the external refractive index is found to be significant, achieving a maximum sensitivity of 18681.82 nm/RIU. The measured results show good agreement with the theoretical predictions. The high sensitivity and the simplicity offer the sensor the potential for many real applications.

Polarization-insensitive widely tunable wavelength conversion has been demonstrated using four-wave mixing in a 64-m-long dispersion-flattened nonlinear photonic crystal fiber. A 3-dB conversion range over 40 nm (1535-1575 nm) is obtained with a flat conversion efficiency of -16 dB and a polarization sensitivity of less than 0.3 dB. The measured power penalty is less than 1 dB for a 10-Gb/s converted nonreturn-to-zero signal at 10/sup -9/ bit-error rate.

We report the first experimental observation of four-wave mixing (FWM) in single-walled carbon nanotubes (SWCNTs) deposited on a D-shaped fiber. FWM-based tunable wavelength conversion of a 10 Gb/s non-return-to-zero signal is demonstrated using a 5-centimeter-long CNT-deposited D-shaped fiber. A power penalty of 4 dB power is obtained in the 10 Gb/s bit-error-rate measurements.

We demonstrate the generation of dark pulses from carbon nanotube (CNT) incorporated erbium-doped fiber ring lasers with net anomalous dispersion. A side-polished fiber coated with CNT layer by optically-driven deposition method is embedded into the laser in order to enhance the birefringence and nonlinearity of the laser cavity. The dual-wavelength domain-wall dark pulses are obtained from the developed CNT-incorporated fiber laser at a relatively low pump threshold of 50.6 mW. Dark pulses repeated at the fifth-order harmonic of the fundamental cavity frequency are observed by adjusting the intra-cavity polarization state.