Figure 2: Absorption properties of the proposed plasmonic piezoelectric nanomechanical resonator.

(a) Simulated (transmission line theory) and measured (FTIR) absorption spectra of a 500-nm-thick AlN slab grounded by a Pt layer (without plasmonic nanostructures). It shows two intrinsic absorption peaks, associated with AlN at 11.3 μm (888 cm⁻¹) and 15.5 μm (647 cm⁻¹)⁴⁰, and one at 4 μm associated with the resonant structure. (b) Simulated and measured absorption spectra of the fabricated plasmonic piezoelectric nanomechanical resonator. The dimensions of the Au patches that compose the metasurface are a=1,635 nm, b=310 nm, and the thickness of the Au, AlN and Pt layers are 50, 500 and 100 nm, respectively. (c,d) Measured and simulated absorption properties of the piezoelectric plasmonic resonant structure with varied Au patch sizes, demonstrating its functionality of spectrally elective detection of infrared radiation in the LWIR range. The unit cell sizes are as follows: design A: a=1,780 nm, b=128 nm; design B: a=1,680 nm, b=253 nm; design C: a=1,640 nm, b=313 nm; design D: a=1,620 nm, b=331 nm.