Theoretical Investigation and Design Optimization of a Metamaterial Enhanced THz Detector for Room Temperature Terahertz Imaging

Abstract

This paper presents the theoretical investigation, finite-element simulation, and design optimization of a Metamaterial Enhanced THz Detector for Room-Temperature Terahertz Imaging. The proposed detector consists of a suspended MEMS platform incorporating a 3×3 array of square-patch MMA unit cells optimized for imaging at 1 THz. Electromagnetic simulations demonstrate polarization-insensitive absorbance exceeding 80 % at the target frequency, with stable performance for incidence angles up to 45°. The suspended platform is supported by Au–SiO₂ bimorph actuators engineered to balance sensitivity and response speed. An analytical model is developed to investigate and identify a trade-off among different performance parameters. For an optimized platform area of 230 µm × 230 µm and a dielectric thickness of 1.5 µm, the detector achieves a designed time constant of 300 ms with 253 µm-long bimorph actuators and 0.8 fractional Au coverage. Finite-element simulations in CoventorWare® validate the analytical predictions, yielding a thermomechanical sensitivity of 0.063°/K and a responsivity of 0.056°/µW, with a temperature rise of 1.25 K under 1 µW incident power. Noise analysis indicates that temperature-fluctuation noise dominates, yielding a noise-equivalent power (NEP) of 2 pW at 295 K. The proposed analytical design methodology provides a method for developing high-sensitivity, room-temperature 
detectors suitable for THz imaging.