We demonstrate remote lasing of atomic nitrogen in air, and investigate the backward coherent stimulated emission. We propose a scheme for remote trace detection using double air lasing and resonant pumping.
There is nothing so practical as a good theory. As a case in point, the compelling need for standoff detection of hazardous gases and vapor indicators of explosives has motivated the development of remotely pumped, scheme(s) which produce radiation in the backward direction [1,2]. Moving from conceptualization to theoretical analysis and experimental verification, we demonstrate that high gain can be achieved in air. Backward air lasing provides possibilities for remote detection [3] as will be discussed.
Air lasing is a concept that refers to remote no-cavity (mirrorless) optical amplification in ambient air with the air constituents as the gain media. Due to the high potential of air lasing in view of applications in atmospheric sensing, a variety of pumping schemes have been proposed so far for building up population-inverted gain media in air and producing forward and/or backward directional lasing emissions. This review paper presents an overview of recent advances in the experimental observations and physical understanding of air lasing in various pumping schemes of air molecules by intense laser fields. Special emphasis is given to the strong-field-induced N 2 + air lasing, the mechanism of which is currently still in a hot debate.
Abstract The research topic of air lasing is of fundamental and practical importance, which has grown rapidly in the past decade. Air lasing, or a laser‐like emission from air species including atomic oxygen, atomic argon, atomic nitrogen, molecular nitrogen, and molecular nitrogen ions, has been investigated vastly in both experiment and theory. In this review, the basic concepts of air lasing are discussed and the crucial role of quantum coherence in the air‐lasing process is highlighted. As an exciting perspective, air lasing not only exhibits important fundamental physics such as superradiance, nonlinear effects, vibrational and rotational dynamics, but also shows potential practical implications toward remote sensing.