Blackett Laboratory, Imperial College London , Prince Consort Road, SW7 2BZ London, United Kingdom.
Nano Lett. 2016 Apr 13;16(4):2878-84. doi: 10.1021/acs.nanolett.6b00811. Epub 2016 Mar 29.
Coherent light sources confining the light below the vacuum wavelength barrier will drive future concepts of nanosensing, nanospectroscopy, and photonic circuits. Here, we directly image the angular emission of such a light source based on single semiconductor nanowire lasers. It is confirmed that the lasing switches from the fundamental mode in a thin ZnO nanowire to an admixture of several transverse modes in thicker nanowires approximately at the multimode cutoff. The mode competition with higher order modes substantially slows down the laser dynamics. We show that efficient photonic mode filtering in tapered nanowires selects the desired fundamental mode for lasing with improved performance including power, efficiency, and directionality important for an optimal coupling between adjacent nanophotonic waveguides.
相干光源将光限制在真空波长壁以下，将推动纳米传感、纳米光谱学和光子电路的未来概念。在这里，我们基于单个半导体纳米线激光器直接对这种光源的角发射进行成像。可以确认，激光从薄的 ZnO 纳米线中的基模切换到较厚纳米线中的几个横向模的混合物，大约在多模截止处。高阶模式与模式竞争极大地减缓了激光动力学。我们表明，锥形纳米线中的高效光子模式滤波选择所需的基本模式用于激光，从而提高了性能，包括功率、效率和方向性，这对于相邻纳米光子波导之间的最佳耦合非常重要。
