High gain backward lasing in air

TL;DR

This paper presents a high gain air laser system that produces backward lasing in air, enabling remote molecular detection by leveraging resonant two-photon processes and prior spark dissociation.

Contribution

It introduces a novel high gain air laser capable of backward lasing in the near infrared using focused ultraviolet pumping and spark dissociation, advancing remote sensing technology.

Findings

Achieved high gain in backward lasing in air

Demonstrated simultaneous forward and backward lasing

Enhanced backward amplification with prior spark dissociation

Abstract

The need for molecular standoff detection has motivated the development of a remotely pumped, high gain air laser that produces lasing in the backward direction and can sample the air as the beam returns. High gain is achieved in the near infrared following pumping with a focused ultraviolet laser. The pumping mechanism is simultaneous resonant two-photon dissociation of molecular oxygen and resonant two-photon pumping of the atomic oxygen fragments. The high gain from the millimeter length focal zone leads to equally strong lasing in the forward and backward directions. Further backward amplification is achieved using prior laser spark dissociation.