Hickson Paul, Hellemeier Joschua, Yang Rui
Opt Lett. 2021 Apr 15;46(8):1792-1795. doi: 10.1364/OL.417910.
Adaptive optics is a key technology for ground-based optical and infrared astronomy, providing high angular resolution and sensitivity. Systems employing laser guide stars can achieve high sky coverage, but their performance is limited by the available return flux. Amplified spontaneous emission could potentially boost the intensity of beacons produced by resonant excitation of atomic or molecular species in the upper atmosphere. This requires the production of a population inversion in an electronic transition that is optically thick to stimulated emission. Mesospheric metals have insufficient column density for amplified spontaneous emission, but atomic oxygen and nitrogen are potential candidates. They could potentially be excited by a high-energy chirped femtosecond pulsed laser, making visible-wavelength transitions accessible. Such lasers can also generate a white-light supercontinuum in the atmosphere. In addition to providing high intensity, the broadband emission from such a source could facilitate the sensing of the tilt component of atmospheric turbulence.
自适应光学是地基光学和红外天文学的一项关键技术，可提供高角分辨率和灵敏度。采用激光导星的系统能够实现高天空覆盖率，但其性能受到可用返回通量的限制。放大自发辐射有可能提高由高层大气中原子或分子物种的共振激发产生的信标强度。这需要在对受激发射光学厚度较大的电子跃迁中产生粒子数反转。中层大气中的金属柱密度不足以实现放大自发辐射，但原子氧和氮是潜在的候选物质。它们有可能被高能量啁啾飞秒脉冲激光激发，从而实现可见光波长跃迁。这种激光还能在大气中产生白光超连续谱。除了提供高强度外，这种光源的宽带发射还可以促进对大气湍流倾斜分量的传感。
