Seed source for plasma compression in the long wavelength infrared

TL;DR

This paper demonstrates the generation of broadband infrared radiation in the 8-14 micron range using laser-induced air plasma, which can serve as a seed for plasma-based amplification of CO2 laser pulses.

Contribution

It introduces a method to produce LWIR seed radiation via two-color laser pulses creating air plasma, with enhanced yield through pulse chirping and insights from simulations.

Findings

Broadband IR radiation observed in 8-14 microns atmospheric window.

Chirping the drive pulse significantly increases LWIR yield.

Simulations suggest pulse duration affects nonlinear refractive index and radiation efficiency.

Abstract

Two color laser pulses are used to form an air plasma and generate broadband infrared radiation suitable as a seed for backward Raman amplification of CO2 laser pulses. Broadband radiation in the atmospheric window from 8-14 microns is observed. The infrared radiation is characterized using a long wavelength grating spectrometer specially designed to accept an ionizing laser filament at its input plane. The LWIR yield is greatly enhanced by chirping the drive pulse. Unidirectional pulse propagation simulations suggest that this is due in part to the dependence of the nonlinear refractive index on the pulse duration.