Photothermal Meta-surface Absorber with Ultra-low Profile Designed for Terahertz Micro-bolometer

This paper proposes a broadband terahertz meta-surface absorber which is designed to be the radiation coupling module of terahertz micro-bolometer. The unit cell of proposed compound meta-surface consists of several basic square unit cells, specifically, 36 basic square unit cells of three different sizes are arranged in an array, perform chessboard-like layout to form a compound unit cell. Simulated absorbing rate of the proposed meta-surface absorber is higher than 80% from 4.46 to 5.76THz (25.4% fractional bandwidth) with a thickness of merely 1.1μm (0.018λ). Since the symmetrical layout of compound unit cell, the absorbing rate keeps stable for incidence with different polarization angles. Moreover, the photothermal response is 8.5K∙mm ² /W by multi-physics simulation, which shows great potential to improve the terahertz micro-bolometer.