Nonlinear Optics of Epsilon-Near-Zero Materials
Abstract
Recent work has demonstrated the exceptional optical properties of materials, known as epsilon-near-zero (ENZ) materials, for which the real part of the dielectric permittivity is extremely small. Among these exceptional properties, the current study will concentrate on the huge enhancement of nonlinear optical response of such materials. This huge response promises to prove useful for myriad applications modem photonics. The current project aims at developing a belier fundamental understanding of the origin of this huge response and of determining limiting processes that could restrict how large the response can become. Much of our current interest in this topic is motiva1ed by our recent observation [14] that the degenerate semiconductor ITO has an ENZ wavelength of about 1.24 microns, and that there is a huge enhancement of the NLO response associated with the ENZ region. We reported a nonlinear coefficient n2 of I.I x IO- IO cm2/W, which is the largest ultrafast (sub-ps) nonlinearity thus far reported. It is 3 .4 x 105 times larger than that of silica glass and is 440 times larger than that of arsenic triselenide glass, which has the largest nonlinear coefficient previously reported. Moreover, the total light-induced change in refractive index is 0.8, which is unprecedentedly large and thus renders this material useful for applications new applications in photonics. In short, we feel that this material and similar ENZ materials will constitute a game changer for the field of photonics. The proposed research program includes the following topics. (1) We will study new theoretical approaches to the understanding of the huge nonlinear response of ENZ materials such as ITO. We note that the response is nonperturbative in that the change in refractive index is much larger than the index itself. We will determine whether a modification of the standard power-series treatment of nonlinear optical response is adequate for describing these situations, or whether entirely new procedures are needed. (2) Self-action effects such as self-focusing and soliton formation lie at the heart of nonlinear optics. These processes promise to be profoundly influenced under ENZ conditions both because the wavelength within the material will become extremely large and because of the extremely large nonlinear coupling. We will study these effects by means of analytical theory, numerical modeling, and experiment. (3) We will investigate the modification of fundamental radiative processes under ENZ conditions. It is well understood that radiative processes such as spontaneous emission depend critically on the density of field modes into which the emitter can radiate. We thus expect a profound modification of the properties of emission and absorption both for single-atom situations and for the situation of superradiance.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810337
Entities
People
- Robert W. Boyd
Organizations
- Army Contracting Command
- United States Army
- University of Rochester