A delay-programmable two-color femtosecond source for multiphoton ionization studies based on chirped-seed NOPA

TL;DR

This paper introduces a delay-programmable two-color femtosecond light source based on chirped-seed NOPA, enabling flexible multiphoton ionization studies with independently tunable pulses.

Contribution

The authors develop a novel chirped-seed NOPA system that allows precise control of two tunable femtosecond pulses with adjustable delay for ultrafast spectroscopy.

Findings

Demonstrated delay-dependent ionization pathways in Li atoms

Achieved independent spectral tuning of two pulses

Validated the source's suitability for bichromatic ultrafast spectroscopy

Abstract

We demonstrate a delay-programmable two-color femtosecond source based on a chirped-seed noncollinear optical parametric amplifier. Introducing controlled dispersion into the seed enables spectral selection through pump-seed delay, allowing flexible generation of two independently tunable pulse components with adjustable relative timing at high repetition rate. The temporal and spectral properties are characterized using nonlinear optical cross-correlation and dispersion-scan measurements. As a benchmark application, the source is employed in a COLTRIMS-based multiphoton ionization experiment on trapped Li atoms, revealing delay-dependent ionization pathways and demonstrating its suitability for bichromatic ultrafast spectroscopy.