Efficient spectral broadening and few-cycle pulse generation with multiple thin water films

TL;DR

This paper demonstrates a novel method using multiple ultrathin water films for efficient supercontinuum generation and few-cycle pulse compression, enabling high-energy ultrafast pulses with broad spectra and high harmonic generation.

Contribution

First demonstration of octave-spanning supercontinuum broadening using multiple ultrathin liquid water films as nonlinear media.

Findings

Supercontinuum covers 380-1050 nm range.

Pulse compressed to 3.9 fs duration.

High-order harmonic spectrum up to 33rd order achieved.

Abstract

High-energy, few-cycle laser pulses are essential for numerous applications in the fields of ultrafast optics and strong-field physics, due to their ultrafast temporal resolution and high peak intensity. In this work, different from the traditional hollow-core fibers and multiple thin solid plates, we represent the first demonstration of the octave-spanning supercontinuum broadening by utilizing multiple ultrathin liquid films (MTLFs) as the nonlinear media. The continuum covers a range from 380 to 1050 nm, corresponding to a Fourier transform limit pulse width of 2.5 fs, when 35 fs Ti:sapphire laser pulse is applied on the MTLFs. The output pulses are compressed to 3.9 fs by employing chirped mirrors. Furthermore, a continuous high-order harmonic spectrum up to the 33rd order is realized by subjecting the compressed laser pulses to interact with Kr gas. The utilization of flowing water films eliminates permanent optical damage and enables wider and stronger spectrum broadening. Therefore, this MTLFs scheme provides new solutions for the generation of highly efficient femtosecond supercontinuum and nonlinear pulse compression, with potential applications in the fields of strong-field physics and attosecond science.