Thermal effects in molecular gas-filled hollow-core fibers
John E. Beetar, M. Nrisimhamurty, Tran-Chau Truong, Yangyang Liu, Michael Chini
Abstract
Few-cycle sources with high average powers are required for applications to attosecond science. Raman-enhanced spectral broadening of Yb-doped laser amplifiers in molecular gases can yield few-cycle pulses, but thermal excitation of vibrational and rotational degrees of freedom may preclude high-power operation. Here we investigate changes in the spectral broadening associated with repetitive laser interactions in an ${{\rm{N}}_2}{\rm{O}}$-filled hollow-core fiber. By comparing experimental measurements of the spectrum associated with each laser pulse to simulations based on a density matrix model, we find that losses in a spectral bandwidth and transmission are largely dominated by thermal excitation of the gas.