Chalcogenide Glass-on-Graphene Photonics

Two-dimensional (2-D) materials are of tremendous interest to integrated photonics given their singular optical characteristics spanning light emission, modulation, saturable absorption, and nonlinear optics. To harness their optical properties, these atomically thin materials are usually attached onto prefabricated devices via a transfer process. In this paper, we present a new route for 2-D material integration with planar photonics. Central to this approach is the use of chalcogenide glass, a multifunctional material which can be directly deposited and patterned on a wide variety of 2-D materials and can simultaneously function as the light guiding medium, a gate dielectric, and a passivation layer for 2-D materials. Besides claiming improved fabrication yield and throughput compared to the traditional transfer process, our technique also enables unconventional multilayer device geometries optimally designed for enhancing light-matter interactions in the 2-D layers. Capitalizing on this facile integration method, we demonstrate a series of high-performance glass-on-graphene devices including ultra-broadband on-chip polarizers, energy-efficient thermo-optic switches, as well as graphene-based mid-infrared (mid-IR) waveguide-integrated photodetectors and modulators

Metal-clad-suspended self-biasing graphene modulator with tunable figure of merit

© 2020, The Author(s). In this letter, a research on the metal-clad-suspended self-biasing graphene modulator is conducted theoretically. The results reveal a higher light–graphene interaction for the more compact modulator. In addition, when the light–graphene interaction is enhanced, the light–metal interaction is also higher, which causes larger insertion loss and makes the figure of merit (FOM) lower. The length of π-phase shift is reduced to 6.35 µm for the Mach–Zehnder modulator, which is the smallest size achieved up to date. The modulator’s FOM can be tuned by changing the air gap (d) between the moveable metal plates and the suspended structure. In the case when this air gap increases, the configuration represents closer fundamental limits design. Moreover, the cut-off mode is discussed, and it has potential to be used in the tunable filter application. This tunable configuration of modulator is believed to have potential that can pave the way to design tunable light–matter interaction device and has evaluated for the near fundamental limits design

Directional lasing in resonant semiconductor nanoantenna arrays

Directional lasing, with a low threshold and high quality factor, in active dielectric nanoantenna arrays is demonstrated. This is achieved through a leaky resonance excited in coupled gallium arsenide (GaAs) nanopillars. The leaky resonance is formed by partially breaking a bound state in the continuum (BIC) generated by the collective, vertical electric dipole resonances excited in the nanopillars for sub-diffractive arrays. By opening an unprotected, diffractive channel along one of the periods of the array one can control the directionality of the emitted light without sacrificing the high Q associated with the BIC mode, thus achieving directional lasing. A quality factor Q = 2750 is achieved at a controlled angle of emission of ~ 3 degrees with respect to the normal of the array with a pumping fluence as low as 10 uJ/cm^2. We demonstrate the possibility to control the lasing directivity and wavelength by changing the geometrical parameters of the nanoantenna array, and by tuning the gain spectrum of GaAs with temperature. Lasing action is demonstrated at different wavelengths and emission at different angles, which can be as large as 25 degrees to the normal. The obtained results provide guidelines for achieving surface emitting laser devices based on active dielectric nanoantennas that are compact and highly transparent.Comment: 29 pages, 15 figure