Ultrashort Pulse Generation and Applications in Optical Fibers.

Research in ultrashort laser pulse generation has developed rapidly over the past decade and as a result, simple methods of generation as well as applications, are now being sought. This thesis examines both the generation as well as the application of ultrashort pulses in optical fibers. A novel method of modelocking called Additive Pulse Modelocking, is investigated experimentally on the Nd:YAG laser in a self-starting configuration. Pulses as short as 6 ps are generated in a stable, cw pulse train. These pulses are the shortest, to date, emanating directly from the lamp-pumped Nd:YAG laser. Also, a synchronously pumped fiber Raman laser, operating in the soliton regime, is built. The laser design employs Additive Pulse Modelocking in a single cavity configuration. In this case, the APM effect is found to be a marginal improvement over the case of synchronous-pumping alone. Cross-phase modulation and walk-off, resulting from the synchronous-pumping, prove to be very strong pulseshaping mechanisms. The ultimate viability of a fiber Raman laser for soliton generation is discussed. Finally, the application of soliton pulses to a fiber gyro is investigated theoretically. Designs for an active and passive gyro are proposed and the theoretical advantages and disadvantages are discussed. A well-designed passive soliton gyro, as described here, has great potential for becoming a practical reality. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).