SPIE 2017 Visiting Lecture - Coherence and Collective Properties of Metallic Nanolasers
Nanolasers, a family of light sources with dimensions smaller than the wavelength of light are one of the latest additions to the laser family. The application of such sources ranges from on-chip optical communication to high-resolution and high-throughput imaging, sensing and spectroscopy. This has fueled interest in developing the ‘ultimate’ nanolaser: a scalable, low-threshold source of radiation that operates at room temperature and occupies a small volume on a chip. However, progress towards realizing this ultimate nano-laser 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. In other words, the miniaturization of laser resonators using dielectric or metallic structures, across all previously proposed solutions, faces two challenges; First, the (eigen) mode scalability, implying the existence of a self-sustained electromagnetic field regardless of the cavity size. Second, the disproportionate reduction of optical gain and cavity losses, which results in a large and/or unattainable lasing threshold as the volume of the resonator is reduced. In this talk, I present our results about lasing in the newly introduced nanoscale, sub-wavelength in all three dimensions, coaxial cavities that potentially solve the resonator scalability challenge by the choice of geometry and metal composition. In particular, I present the design, fabrication, characterization, and analysis that resulted in the smallest, room-temperature, continuous wave, telecommunication wavelength laser to date. Furthermore, by utilizing the unique properties of the coaxial cavities, which may have a single non-degenerate mode, I discuss the possibility of thresholdless lasing that provides a scalable solution to overcome the metal losses. I will then explain how to measure the second order coherence function for such light sources in order to verify if they are indeed capable of generating coherent radiation. At the end, I will discuss the possibility of collective behaviors in arrays of nanoscale lasers.