Optical Science and Engineering ETDs


Craig Robin

Publication Date



This dissertation presents experimental and theoretical studies of high power, single-frequency, ytterbium-doped photonic crystal fiber amplifiers. The objective of this effort is to identify issues which limit power scaling and develop novel techniques to overcome these limitations. Historically, stimulated Brillouin scattering (SBS) has been the primary obstacle in the realization of high power single-frequency fiber amplifiers. A novel acoustically tailored photonic crystal fiber design, having a reduced Brillouin gain coefficient of 1.2x10-11 m/W, is demonstrated. The fiber design is such that it may be used in conjunction with other SBS mitigation techniques, which increases the nonlinear threshold beyond the current state of the art. In the successful suppression of SBS, a new regime of single-frequency photonic crystal fiber amplifier power scaling is explored. Instabilities in the transverse mode is observed at increasing output powers. Mitigation of this effect is demonstrated experimentally. This empirical data is used as the basis for a theoretical treatment of the problem, which provides direction for future fiber amplifier designs. The culmination of this work results in the successful utilization of the acoustically tailored photonic crystal fiber in a single-frequency counter-pumped amplifier configuration, yielding close to 500 W output power and near diffraction-limited beam quality.

Degree Name

Optical Science and Engineering

Level of Degree


Department Name

Optical Science and Engineering

First Advisor

Lester, Luke

First Committee Member (Chair)

Sheik-Bahae, Mansoor

Second Committee Member

Dajani, Iyad

Third Committee Member

Diels, Jean-Claude


Air Force Research Laboratory, Air Force Office of Scientific Research, High Energy Laser Joint Technology Office

Document Type