Rashidi Mohammad, Haggren Tuomas, Su Zhicheng, Jagadish Chennupati, Mokkapati Sudha, Tan Hark H
Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
Nano Lett. 2021 May 12;21(9):3901-3907. doi: 10.1021/acs.nanolett.1c00455. Epub 2021 Apr 26.
Random lasers are promising, easy-to-fabricate light sources that rely on scattering instead of well-defined optical cavities. We demonstrate random lasing in GaAs nanowires using both randomly oriented and vertically aligned arrays. These configurations are shown to lase in both resonant and nonresonant modes, where aligned nanowires support predominantly resonant lasing and randomly oriented favors nonresonant lasing. On the basis of numerical simulations, aligning the nanowires increases the system's scattering efficiency leading to higher quality factor modes and thus favoring the resonant modes. We further demonstrate two methods to optically suppress resonant mode lasing by increasing the number of excited modes. The light output-light input curves show a pronounced kink for the resonant lasing mode while the nonresonant mode is kink-free. The resonant lasing modes may be used as tunable lasers, and the nonresonant modes exhibit near-thresholdless amplification. Switching between lasing modes opens up new opportunities to use lasers in broader applications.
随机激光器是一种很有前景且易于制造的光源，它依靠散射而非定义明确的光学腔。我们利用随机取向和垂直排列的阵列在砷化镓纳米线中演示了随机激光发射。这些结构在共振和非共振模式下均能实现激光发射，其中排列整齐的纳米线主要支持共振激光发射，而随机取向的纳米线则有利于非共振激光发射。基于数值模拟，排列纳米线可提高系统的散射效率，从而产生更高品质因数的模式，进而有利于共振模式。我们还展示了两种通过增加激发模式数量来光学抑制共振模式激光发射的方法。光输出 - 光输入曲线显示，共振激光发射模式有明显的拐点，而非共振模式则无拐点。共振激光发射模式可作为可调谐激光器使用，非共振模式则表现出近阈值无放大特性。在不同激光发射模式之间切换为激光在更广泛应用中开辟了新机遇。
