The active and nonlinear graphene properties are limited due to weak light-matter interaction between the ultrathin graphene and the incident light. In this work, we present enhanced nonlinear effects at the low terahertz (THz) range by designing a new patterned graphene hyperbolic metamaterial (GHMM). More specifically, it is demonstrated that the third harmonic generation (THG) can be significantly enhanced by the proposed GHMM due to the field enhancement at the resonance as well as the supported slow-light response that fosters strong light–matter interaction.
We present here an ultrasensitive optical sensing technique based on the parity-time (PT)-symmetric non-Hermitian metasurfaces. The system is composed of a pair of active and passive metasurfaces with the subtle gain-loss balance. Specifically, these two metasurfaces are made of the photoexcited, nanopatterned 2D material (gain) and the lossy metallic structure (i.e., loss). By suitably tailoring the impedance profiles of the PT-symmetric metasurfaces, the system can exhibit an exotic point where the coherent perfect absorption (CPA) and lasing could occur at the same wavelength, switchable via tuning the complex amplitude of incoming light. At this point, tiny perturbation in the effective optical impedance could drastically vary eigenvalues of the scattering matrix, leading to greatly modulated scattering coefficients and output factor, well beyond conventional optical sensors. Our results show that the proposed PTsymmetric metasurfaces may enable ultrasensitive optical sensors for detecting low-density chemical, gas and molecular agents, as well as refractive-index sensing of a nanofilm.
Efficient conversion of long-wavelength light into direct current represents a great potential for photodetection, photocatalyst, and photovoltaics, with a variety of applications in sensing, security, defense, and emissive infrared energy harvesting. We propose here a new type of plasmo-electronic nanodevice, engineered as the hyperbolic metamaterial (HMM), to efficiently trap and nonlinearly rectify the incoming infrared radiation. These HMM-based nanodevices are constituted by the periodic, dissimilar metal-insulator-metal (MIM) heterojunctions, whose homogenized material properties enable the perfect absorption of infrared radiation and the localization of optical fields. The nonlinear optical rectification driven by the multiphoton-assisted tunneling in the MIM heterojunctions can efficiently convert the infrared radiation into the DC electricity (photocurrent). Most interestingly, the wideband or frequency-selective photon-to-electron conversion can be controlled via the design of HMM nanostructures. Our theoretical and numerical results demonstrate that the zero-bias responsivity of the HMM-based nanodevices can be up to ~100 mA/W in the mid-infrared regime.
Conference Committee Involvement (2)
Micro- and Nanotechnology Sensors, Systems, and Applications XII
27 April 2020 | Online Only, California, United States
Micro- and Nanotechnology Sensors, Systems, and Applications XI
14 April 2019 | Baltimore, Maryland, United States