High Power Mid-IR Laser System for ESASE

The Department of Energy seeks the development of advanced laser systems for current-enhanced self- amplified spontaneous emission (ESASE) free-electron lasers for ultra-short x-ray generation. Improvements in the technology will come from the use of driving lasers operating at wavelengths longer than those from Ti:sapphire-based systems. To function, the lasers must achieve the state-of-the-art in short-pulse duration, phase stabilization, and coherence. Current laser systems suffer from complexity due to the use of multiple nonlinear stages to achieve the desired wavelength and have issues with power scaling. Q-Peak proposes to develop a novel, mid-infrared 50-fs pulse, high-pulse-energy, femtosecond oscillatorregenerative chirped pulse amplifier (CPA), hybrid laser system utilizing fiber and solid-state lasers. The high peak power, femtosecond CEP-stabilized output pulses at 2.5 m can be used as driver for ESASE. All the elements of the system proposed are based on technology that has undergone significant development at Q-Peak and continues to be advanced for applications in both Government and commercial systems. In the Phase I program we demonstrated fiber laser-pumped femtosecond mid-IR solid-state oscillator with 109 fs pulse duration. Supercontinuum generation was demonstrated with a chalcogenide fiber taper and it enables a carrier-envelope-phase (CEP) stabilization of the system. This laser is suitable as a seed source for high-power mid-IR amplified femtosecond laser system. In the proposed Phase II program Q-Peak will develop a diode-pumped femtosecond oscillator-regenerative amplifier laser system with 5 GW peak power output at a 10 kHz repetition rate. The system will be CEP stabilized to be suitable for ESASE and other high field physics applications. Commercial Applications and Other Benefits: The proposed laser system will be a new tool for x-ray free-electron laser-based light sources. It will also demonstrate a path to scale the laser system to the TW peak power level. We also propose to develop a commercial prototype of a frequency mid-IR comb generator based on a diode-pumped femtosecond oscillator and fiber supercontinuum generation. This product can be used in a variety of applications such as environmental analysis, remote-sensing, spectroscopy, medicine and astronomy.