Swarm Optimization of 2-D Metasurface Structure for Low-Crosstalk LWIR Filter Arrays

Recent developments in division of focal plane (DoFP) sensor technology have led to the availability of compact snapshot multispectral imagers. However, many of these imagers based on micro-/nano-filter structures encounter issues, such as crosstalk among the units. To address this, we propose a 2-D metasurface structure that modulates light to capture spectral information in multiple bands in the long-wave infrared (LWIR) spectrum. We also present a multiobjective optimization method to optimize the 2-D metasurface structure as an LWIR multispectral filter array with low crosstalk. The proposed multiobjective optimization method, based on a particle swarm optimization algorithm, finds the optimal parameters for the 2-D metasurface structure to minimize the crosstalk between the units of the filter array. Since the crosstalk between two bands may not be measured directly, we compute spectral aliasing between two bands to estimate the amount of crosstalk. We transform the problem of reducing crosstalk into a multiobjective optimization problem to minimize spectral aliasing. Simulation results demonstrate that our proposed filter array design technique reduces crosstalk among filter array units, enabling high-fidelity spectral characteristics in snapshot LWIR multispectral imaging.