A stable and broad bandwidth multiwavelength fiberring laser suitable for use in dense wavelength-division-multiplexing systems is demonstrated. A highly nonlinear photonic crystal fiber is inserted in the ring cavity to stabilize the power fluctuation and broaden the output spectrum. A thin-film Fabry-Pérot etalon filter is used to get stable wavelength lasing. A Sagnac filter is employed to achieve uniform power distribution at each wavelength at the laser output. A laser with a power fluctuation about 0.1dB in each wavelength within 20min and with wavelength shift of less than 0.016 nm within 10min is achieved. A stable 24-wavelength lasing operation with wavelength spacing of 0.8 nm within the 3-dB spectral range of 1573-1594 nm and signal-to-noise ratio better than 48dB is observed experimentally.

We demonstrate a 10 Gbit/s nonreturn-to-zero wavelength converter based on four-wave mixing in a 20m highly nonlinear photonic crystal fiber. The tunable wavelength conversion bandwidth 3dB is about 100nm. The conversion efficiency is -16dB when the pump power is 22.5dBm. Phase modulation was not used to suppress the stimulated Brillouin scattering; thus the linewidth of the converted wavelength remained very narrow. The eye diagrams show that there is no additional noise during wavelength conversion. The measured power penalty at a 10-9 bit-error-rate level is about 0.7dB.

Silicon oxynitride rectangular optical waveguides have been fabricated by plasma-enhanced chemical vapor deposition and dry etching. The propagation loss and polarization dependent loss in as-grown samples show a substantial reduction after the samples have been annealed. Birefringence measurements before and after annealing on waveguides of different widths suggest that the waveguide modal birefringence is strongly affected by both waveguide geometry and stress in the material. Hence, the modal birefringence can be minimized by designing the appropriate waveguide geometry to compensate for any stress effects.

An optical switch structure which combines a planar lightwave circuit and liquid crystal is proposed and experimentally demonstrated. The switching is realized by inducing total internal reflection through controlling the refractive index of the liquid crystal. The principle and the design of the integrated optical switch are described. Experimental results suggest that anchoring of the liquid crystal molecules on nonplanar structures is very crucial in affecting the switching performance.

An optical switch structure based on total internal reflection effects in intersecting silicon oxynitride waveguides has been designed and successfully fabricated. The optical reflection losses of the waveguides have been analyzed and compared with experimental results. It was shown that, apart from materials and scattering losses, the major factors contributing to the reflection losses are waveguide width, reflection facet displacement, and reflection facet tilt angle, with the last factor being the most critical in deciding the overall loss of the device.