Abstract

The use of optical fiber amplifiers in optical telecommunication systems has opened up many new possibilities with the amplifier's large gain and wide spectral bandwidth. They include ultra-long distance signal transmission without repeaters, and multi channel optical frequency division multiplexing. Very short optical pulses, optical soliton pulses, and wavelength tunable laser sources with extremely narrow linewidth are also of great interest as light source for broad-band optical communication. More recently, new applications of the optical fiber amplifiers to sensors have been introduced.^1–5 They are in forms of various types of fiber lasers whose output optical frequencies or temporal properties are determined by the optical path-lengths of laser cavities. The magnitude of external pertubations that change the optical pathlength of the cavity can be measured by monitoring the output characteristics of the laser. To achieve good performance from the fiber laser sensors, the longitudinal mode and polarization properties of the fiber laser have to be understood in detail.

© 1995 IEEE