Department of Electrical and Computer Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0407, USA.
Nature. 2012 Feb 8;482(7384):204-7. doi: 10.1038/nature10840.
The effects of cavity quantum electrodynamics (QED), caused by the interaction of matter and the electromagnetic field in subwavelength resonant structures, have been the subject of intense research in recent years. The generation of coherent radiation by subwavelength resonant structures has attracted considerable interest, not only as a means of exploring the QED effects that emerge at small volume, but also for its potential in applications ranging from on-chip optical communication to ultrahigh-resolution and high-throughput imaging, sensing and spectroscopy. One such strand of research is aimed at developing the 'ultimate' nanolaser: a scalable, low-threshold, efficient source of radiation that operates at room temperature and occupies a small volume on a chip. Different resonators have been proposed for the realization of such a nanolaser--microdisk and photonic bandgap resonators, and, more recently, metallic, metallo-dielectric and plasmonic resonators. But progress towards realizing the ultimate nanolaser has been hindered by the lack of a systematic approach to scaling down the size of the laser cavity without significantly increasing the threshold power required for lasing. Here we describe a family of coaxial nanostructured cavities that potentially solve the resonator scalability challenge by means of their geometry and metal composition. Using these coaxial nanocavities, we demonstrate the smallest room-temperature, continuous-wave telecommunications-frequency laser to date. In addition, by further modifying the design of these coaxial nanocavities, we achieve thresholdless lasing with a broadband gain medium. In addition to enabling laser applications, these nanoscale resonators should provide a powerful platform for the development of other QED devices and metamaterials in which atom-field interactions generate new functionalities.
近年来，由于物质与亚波长共振结构中的电磁场相互作用而产生的腔量子电动力学（QED）的影响一直是研究的热点。亚波长共振结构产生相干辐射引起了广泛的兴趣，不仅因为它是探索小体积中出现的 QED 效应的一种手段，而且还因为它在从片上光学通信到超高分辨率和高通量成像、传感和光谱学等应用中的潜在应用。其中一个研究方向是开发“终极”纳米激光器：一种可扩展、低阈值、高效率的辐射源，在室温下工作，在芯片上占据很小的体积。已经提出了不同的共振器来实现这种纳米激光器——微盘和光子带隙共振器，以及最近的金属、金属电介质和等离子体共振器。但是，朝着实现终极纳米激光器的进展受到缺乏系统方法的阻碍，无法在不显著增加激光阈值功率的情况下缩小激光腔的尺寸。在这里，我们描述了一类同轴纳米结构腔，通过其几何形状和金属成分来解决共振器可扩展性的挑战。使用这些同轴纳米腔，我们演示了迄今为止最小的室温连续波电信频率激光。此外，通过进一步修改这些同轴纳米腔的设计，我们实现了具有宽带增益介质的无阈值激光。除了实现激光应用外，这些纳米级共振器还应为其他 QED 器件和超材料的发展提供一个强大的平台，其中原子场相互作用产生新的功能。
