Overview of Sandia's fiber laser program

Sandia National Laboratories' program in high-power fiber lasers has emphasized development of enabling technologies for power scaling and gaining a quantitative understanding of fundamental limits, particularly for high-peak-power, pulsed fiber sources. This paper provides an overview of the program, which includes: (1) power scaling of diffractionlimited fiber amplifiers by bend-loss-induced mode filtering to produce >1 MW peak power and >1 mJ pulse energy with a practical system architecture; (2) demonstration of a widely tunable repetition rate (7.1-27 kHz) while maintaining constant pulse duration and pulse energy, linear output polarization, diffraction-limited beam quality, and <1% pulse-energy fluctuations; (3) development of microlaser seed sources optimized for efficient energy extraction; (4) high-fidelity, three-dimensional, time-dependent modeling of fiber amplifiers, including nonlinear processes; (5) quantitative assessment of the limiting effects of four-wave mixing and self-focusing on fiber-amplifier performance; (6) nonlinear frequency conversion to efficiently generate mid-infrared through deep-ultraviolet radiation; (7) direct diode-bar pumping of a fiber laser using embedded-mirror side pumping, which provides 2.0x higher efficiency and much more compact packaging than traditional approaches employing formatted, fiber-coupled diode bars; and (8) fundamental studies of materials properties, including optical damage, photodarkening, and gamma-radiation- induced darkening.