Development of Mid-Infrared Lasers for Soft X-Ray High Harmonic Generation

Drew Morrill, University of Colorado Boulder

Photo of Drew Morrill

High harmonic generation (HHG) is an extremely nonlinear optical process in which wavelengths are converted from the micron scale (~1 eV) down to the scale of 10s of or even single nanometers (~1000 eV). HHG is a finely balanced process with exacting demands on the laser system. In this talk, I will describe my team’s work in the field of laser physics as we design and construct a novel laser source that will enable the generation of coherent, soft X-ray light in a stable, table-top scale format. The home-built laser system is a 1 kHz optical parametric chirped pulse amplifier (OPCPA). The system is comprised of a number of components. I will discuss a stable, all-fiber front end, which employs a highly nonlinear fiber to provide synchronized seed pulses at both 1.5 micron (Erbium wavelengths) and 1 micron (Ytterbium wavelengths). The 1 micron pulses are amplified to about 15 mJ in a cryogenically cooled Yb:YAG regenerative amplifier and provide the pump for the OPCPA. The 1.5 micron (signal) pulses are stretched and given spectral and amplitude modulation using a pulse shaper. The signal and pump are mixed in a series of four periodically poled lithium niobate (PPLN) crystals, resulting in several hundred microjoules of pulse energy at 3.1 microns with a flat spectral phase. Simultaneously, we are developing a capillary based HHG source, which is made suitable for a mid-infrared driving laser through the use of an anti-resonant hollow core fiber. Finally, I will discuss my practicum work at Lawrence Livermore National Laboratory in the area of power scaling of fiber laser amplifiers.

Abstract Author(s): Drew Morrill, Dan Carlson, Will Hettel, Michaël Hemmer, Margaret Murnane, Henry Kapteyn