Methods and apparatus for generating a frequency comb and for its use in analyzing materials and in telecommunications. The frequency comb is generated by passing pulsed light from a laser through an optical fiber having a constriction. The frequency comb comprises a plurality of monochromatic components separated in frequency by a substantially constant frequency increment. The monochromatic components are used to probe materials for analysis. In preferred embodiments, the materials are DNA, RNA, PNA and other biologically important molecules and polymers. Optical responses are observed and used to analyze or identify samples. In telecommunication applications, the individual monochromatic components serve as carriers for individual communication channels that can carry information of any of a variety of types, such as voice, data and images.