Unprecedented material compatibility and ease of integration, in addition to the unique and diverse optoelectronic properties of layered materials (such as graphene, transition metal dichalcogenides and black phosphorous) have generated significant interest in their utilization in nanophotonic devices. While initial nanophotonic experiments primarily focused on light-sources, modulators, and detectors, recently researchers have also demonstrated nonlinear optical devices using layered materials. The extreme thinness of the materials however, limit the effective light-matter interaction. This problem can be solved by using an optical resonator, where light is confined both temporally and spatially to enhance the light-matter interaction. I will talk about some of the recent cavity-2D material devices developed in my lab. These devices include optically pumped lasers , cavity enhanced LED  and second harmonic generating devices . I will explain how layered materials present a unique opportunity to engineer the overlap between modes at different harmonic frequencies for efficient nonlinear optics . I will also talk about some of the new type of cavities we are exploring in our lab using dielectric freeform metasurfaces , which can operate on two-dimensional signal, or an image. Using nonlinear 2D materials inside such cavity we can potentially perform cavity enhanced nonlinear image processing.
S. Wu, S. Buckley, J. R. Schaibley, L. Feng, J. Yan, D. G. Mandrus, F. Hatami, W. Yao, J. Vucˇkovic´, A. Majumdar, and X. Xu, "Monolayer semiconductor nanocavity lasers with ultralow thresholds," Nature, vol. 520, pp. 69-72, 2015.
C.-H. Liu, G. Clark, T. Fryett, S. Wu, J. Zheng, F. Hatami, X. Xu, and A. Majumdar, "Nanocavity Integrated van der Waals Heterostructure Light-Emitting Tunneling Diode," Nano Letters, 2016/12/07 2016.
K. F. Taylor, L. S. Kyle, Z. Jiajiu, L. Chang-Hua, X. Xiaodong, and M. Arka, "Silicon photonic crystal cavity enhanced second-harmonic generation from monolayer WSe 2," 2D Materials, vol. 4, p. 015031, 2017.