Mechanical and Aerospace Engineering Department, Princeton University, Princeton, NJ 08544, USA.
Science. 2011 Jan 28;331(6016):442-5. doi: 10.1126/science.1199492.
The compelling need for standoff detection of hazardous gases and vapor indicators of explosives 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. We demonstrate that high gain can be achieved in the near-infrared region by 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 with the use of earlier laser spark dissociation. Low-divergence backward air lasing provides possibilities for remote detection.
强烈需要对危险气体和爆炸物蒸气指示剂进行远距离探测，这促使人们开发了一种远程泵送、高增益的空气激光器，该激光器能够在反向产生激光，并在光束返回时对空气进行采样。我们证明，通过聚焦的紫外激光泵浦可以在近红外区域获得高增益。泵浦机制是分子氧的同时共振双光子解离和原子氧碎片的共振双光子泵浦。毫米长度焦区的高增益导致正向和反向的激光强度相等。早期激光火花解离的使用实现了进一步的反向放大。低发散度的反向空气激光为远程探测提供了可能性。
