Multi-State Control Of Spectral Response In Coupled 2d Material Systems

Reconfigurable optical systems capable of reproducing complex spectral profiles have broad relevance across optics and photonics. Here, we present a framework for designing reconfigurable metamaterials using active cells that incorporate gate-tunable two-dimensional (2D) materials. Due to their reduced dimensionality, 2D materials exhibit high sensitivity to electric fields, allowing for the tuning of their optical properties through the application of external voltage. By assembling nanopatterned 2D materials into coupled arrays, a single solid-state device can be used to synthesize a wide range of spectral responses. However, the design of such multi-state devices is challenging due to the inherently high-dimensional parameter space involved.<br/><br/>To address this challenge, we present a coupled-mode analytical framework to model the relationship between system control inputs (e.g., voltage) and the manifold of optical outputs embodying multiple spectral resonances. Using graphene as a model 2D material, we investigate the potential for synthesizing complex thermal-infrared spectral absorption profiles within the spectral range where graphene supports surface plasmon polaritons. By employing this coupled framework, we demonstrate that a single judiciously designed array of graphene resonators can dynamically switch between distinct absorption spectra of multiple gases, mimicking both narrow spectral features and broad spectral envelopes. We validate our model by comparing it to full numerical EM simulations, demonstrating a high level of agreement with orders of magnitude speed up in computation time. In addition, through the integration of auto-differentiation algorithms, our model enables efficient gradient-based optimization over the multi-state, multi-spectral design space. We elucidate the tradeoffs between the device complexity, number of resonators and their spectral performance, in both planar and stratified configurations. This approach has potential for various applications in sensing, energy harvesting, and signature management.