A multiwavelength source having precise channel spacing based on external modulation and fiber Kerr nonlinearity

Abstract

WDM is an attractive option for providing increased capacity in lightwave transmission systems and routing capability within optical networks. As the demand for the number of wavelengths in transport and local systems will continue to increase, new technological capabilities and designs for transmitters will be required to minimize the complexity and cost of the use of such large numbers of closely spaced wavelengths. Several approaches are being considered to address the wavelength stabilization and inventory issues. A very attractive solution to these problems is to use a wavelength-selectable laser. Wavelength-selectable source chips that can reach 4-6 channels have been reported, however reaching large numbers would heighten integration issues, such as yield and packaging. Recently, alternative approaches to multiwavelength sources (MWS) that can generate many or all of the system wavelengths have been reported. One of these sources consists of a mode-locked laser of the precise length to produce pulses at a repetition rate of 50 GHz and, hence, discrete cw frequency components with a separation of 50 GHz. Here we propose and demonstrate an MWS of cw wavelength channels that is based on a cw laser, external modulator, and the Kerr nonlinearity in an optical fiber.