Two-dimensional Layered Material-Based Nonlinear Optical Upconverters

Two-dimensional layered materials are emerging as promising nonlinear optical media due to their order crystalline arrangement, strong nonlinear optical susceptibility, interesting layer dependence of optical properties, high refractive index, broad transparency window, and ease of fabricating devices using dry-transfer and nanoscale patterning techniques. In this work, an overview of some of our efforts to realize frequency upconversion devices using multilayer two-dimensional layered material in Fabry Perot cavity [1, 2] and sub-wavelength disk structures [3] will be presented. Up-conversion is particularly an important functionality to convert optical signals from wavelengths were good quality detectors are not available to the visible or near infrared range, where good quality silicon based detectors are widely used. Such up-conversion functionalities find key applications in infrared spectroscopy and imaging. Traditionally, bulky nonlinear optical crystals requiring careful phase-matching have been used for up-conversion. Recently, there is interest performing upconversion using miniaturized structures such as sub-wavelength metasurfaces and two-dimensional layered materials. First, inverse design of such structures using hybrid genetic optimization and particle swarm optimization in order to determine the structure dimensions with the goal of maximizing the far-field radiated nonlinear optical signal will be discussed. The fabrication of these structures using standard cleanroom processing techniques and the experimental characterization of the fabricated structures using linear reflectance and nonlinear optical studies will be discussed. The future outlook of such materials being utilized for mainstream nonlinear photonic applications will also be discussed.