HIGH POWER PULSED FIBER LASER SOURCES AND THEIR USE IN TERAHERTZ GENERATION 

In this dissertation I report the development of high power pulsed fiber laser systems. These systems utilize phosphate glass fiber for active elements, instead of the industry-standard silica fiber. Because the phosphate glass allows for much higher doping of rare-earth ions than silica fibers, much shorter phosphate fibers can be used to achieve the same gain as longer silica fibers.This single-frequency laser technology was used to develop an all-fiber actively Q-switched fiber lasers. A short cavity is used to create large spacing between longitudinal modes. Using this method, we demonstrated the first all-fiber Q-switched fiber laser in the 1 micron region.In addition to creating high peak powers with Q-switched lasers, created even higher powers using fiber amplifier systems. High power fiber lasers typically produce spectral broadening through the nonlinear effects of stimulated Raman scattering, stimulated Brullion scattering, and self-phase modulation. The thresholds for these nonlinearities scale inversely with intensity and length. Thus, we used a short phosphate fiber gain stage to reduce the length, and a large core fiber final stage to reduce intensity. In this way we were able to generate high peak power pulses while avoiding visible nonlinearities, and keeping a narrow bandwidth.The immediate goal of developing these high power fiber laser systems was to generate narrowband terahertz radiation. Two different wavelengths were combined into the final amplifier stage at orthogonal polarizations. These were collimated and directed into a GaSe crystal, which has a very high figure of merit for THz generation. The two wavelengths combined in the crystal through the process of nonlinear difference frequency generation. This produced a narrowband beam of THz pulses, at higher powers than previous narrowband THz pulses produced by eyesafe fiber lasers.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Physics

Grantor dc:publisher

The University of Arizona.

Year dc:date.issued

2008

Author dc:creator

• Leigh, Matthew

Advisor dc:contributor.advisor

• Peyghambarian, Nasser

Committee members dc:contributor.committeemember

• Jiang, Shibin
• Wright, Ewan
• Bickel, William
• Mazumdar, Sumit

• Fiber Amplifier
• Fiber Laser
• Nonlinear Optics
• Q-switched laser
• Single Frequency Laser
• Terahertz

Statement dc:rights

• Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.

Language dc:language.iso

EN

Handle dc:identifier.uri

http://hdl.handle.net/10150/193797

OAI identifier oai:identifier

oai:repository.arizona.edu:10150/193797