Parity-Time Symmetry in Optics and Photonics
The prospect of judiciously utilizing both optical gain and loss has been recently suggested as a means to control the flow of light. This proposition makes use of some newly developed concepts based on non-Hermiticity and parity-time (PT) symmetry-ideas first conceived within quantum field theories. By harnessing such notions, recent works indicate that novel synthetic structures and devices with counter-intuitive properties can be realized – potentially enabling new possibilities in the field of optics and integrated photonics. Non-Hermitian degeneracies, also known as exceptional points (EPs), have also emerged as a new paradigm for engineering the response of optical systems. In this talk, we provide an overview of recent developments in this newly emerging field. The use of other type symmetries in photonics will be also discussed.
Demetri Christodoulides is a Pegasus and Cobb Family Endowed Chair Professor at CREOL-the College of Optics and Photonics of the University of Central Florida. He received his Ph.D. degree from Johns Hopkins University in 1986 and he subsequently joined Bellcore as a post-doctoral fellow at Murray Hill. Between 1988 and 2002 he was with the faculty of the Department of Electrical Engineering at Lehigh University. His research interests include linear and nonlinear optical beam interactions, synthetic optical materials, optical solitons, and quantum electronics. He has authored and co-authored more than 325 papers. He is a Fellow of the Optical Society of America and the American Physical Society. In 2011 he received the R.W. Wood Prize of OSA.
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.