Department of Physics and ‡Institute of Nanoengineering and Microsystems, National Tsing-Hua University , Hsinchu, Taiwan 30013, Republic of China.
Nano Lett. 2011 Oct 12;11(10):4256-60. doi: 10.1021/nl2022477. Epub 2011 Sep 8.
Realization of smaller and faster coherent light sources is critically important for the emerging applications in nanophotonics and information technology. Semiconductor lasers are arguably the most suitable candidate for such purposes. However, the minimum size of conventional semiconductor lasers utilizing dielectric optical cavities for sustaining laser oscillation is ultimately governed by the diffraction limit (∼(λ/2n)(3) for three-dimensional (3D) cavities, where λ is the free-space wavelength and n is the refractive index). Here, we demonstrate the 3D subdiffraction-limited laser operation in the green spectral region based on a metal-oxide-semiconductor (MOS) structure, comprising a bundle of green-emitting InGaN/GaN nanorods strongly coupled to a gold plate through a SiO(2) dielectric nanogap layer. In this plasmonic nanocavity structure, the analogue of MOS-type "nanocapacitor" in nanoelectronics leads to the confinement of the plasmonic field into a 3D mode volume of 8.0 × 10(-4) μm(3) (∼0.14(λ/2n)(3)).
实现更小、更快的相干光源对于新兴的纳米光子学和信息技术应用至关重要。半导体激光器可以说是实现这一目标的最佳候选者。然而，利用介电光腔维持激光振荡的传统半导体激光器的最小尺寸最终受限于衍射极限（对于三维（3D）腔，约为 (λ/2n)(3)，其中 λ 是自由空间波长，n 是折射率）。在这里，我们基于金属-氧化物-半导体（MOS）结构演示了在绿光区域的 3D 亚衍射极限激光操作，该结构包含一束通过二氧化硅（SiO(2)）介电纳米间隙层与金盘强耦合的绿光发射的 InGaN/GaN 纳米棒。在这种等离子体纳米腔结构中，类比于纳米电子学中的 MOS 型“纳米电容器”的结构导致等离子体场被限制在 3D 模式体积为 8.0×10(-4) μm(3)（约为 0.14(λ/2n)(3)）。
