Stable multiwavelength lasing is demonstrated with a novel laser, in which a semiconductor optical amplifier offers optical gain and cascaded sampled fiber gratings serve as a comb filter. Five lasing lines are obtained with a fixed wavelength spacing of 0.8 nm. Optical power fluctuations among the lasing lines are improved by adjusting reflectivity profile through the cascade of two sampled gratings.

Impacts of residual facet reflection on the performances of wavelength converters based on semiconductor optical amplifiers (SOAs) are theoretically investigated. Residual facet reflection definitely degrades the converter performance. A probe signal feedback scheme is introduced to improve the wavelength conversion characteristics. With the probe signal feedback, the wavelength conversion parameters, including extinction ratio, frequency chirping and modulation response, can be enhanced, and the facet reflection limits are relaxed due to the enhancement of carrier-photon interaction.

Noninverted wavelength conversion has been demonstrated using Fabry-Perot semiconductor optical amplifiers (FP-SOAs), and its mechanism is theoretically analyzed. The noninverted behavior is dominated by the shift of gain spectrum in the FP-SOA. Increasing the input optical power suppresses the spontaneous emission and drives the gain spectrum toward the longer wavelength side due to the enhancement of carrier-photon interaction. The performance of wavelength converters is improved owing to the resonant effect at the probe wavelength and this type of converter provides an effective approach for wavelength conversion in the future broadband networks.

Multiwavelength oscillation is demonstrated with a novel laser scheme, in which cascaded second-order nonlinearity in a periodically poled LiNbO3 (PPLN) waveguide is used to double the lasing lines. Twenty-two wavelengths approaching S- and L-bands are simultaneously achieved with a channel spacing of 1.6 nm, and the band separation is changeable. The number of wavelengths and channel spacing can be controlled by the adjustment of the tunable Fabry-Perot (FP) etalon and light polarization states in the laser cavity.

Simultaneous multiwavelength lasing is demonstrated exploiting intracavity polarization hole burning in an erbium-doped fiber laser. Experimental results indicate that polarization hole burning can be enhanced by the changes of the light polarization states and bias current of optical MQW waveguide which serves as reflector in the laser. Eleven wavelengths with 0.9 nm spacing are generated at room temperature.