Recovery Act - Development of a Fiber Based Source of High Average Power Ultrafast Pulses at 2.0 Microns

Bright coherent light sources in the soft x-ray region of the spectrum are useful for a variety of applications of interest to DOE in the basic sciences, nanoscience and biology, and for technological applications. At Free-Electron Laser Facilities, peak power output of the x-ray pulses is enhanced by using a mid-infrared laser pulse instead of a near-infrared pulse. The current front end for mid-infrared pulse generation is a large research-grade titanium-sapphire laser amplifier. Fiber lasers constitute a promising technology for robust ultrafast systems in a compact footprint. In this project, we will make use of recent advances in ultrafast fiber laser design in combination with optical parametric amplification to convert the laser output to 2 micron wavelength for use in free-electron lasers or high harmonic generation. We will make use of the technique of crossed-polarized wave generation to remove the pedestals that tend to limit pulse duration in fiber lasers. We conducted simulations of the crossed-polarized wave pulse compression process to verify feasibility for 2 micron pulse compression. We also constructed a fiber oscillator operating in the all-normal dispersion regime, which allows high output power simultaneous with pulses that are compressible to sub-100 fs. This oscillator will form the front end of the amplifier to be built in Phase II. We plan to implement the fiber laser amplifier system we designed in the Phase I project. We expect to obtain 100fs, 250