Realization of a high-performance quantum ratchet infrared photodetector in the very long wavelength infrared regime with a patchwork metasurface

Abstract Enduring infinitesimal development from a research standpoint, the very long wavelength infrared (VLWIR) band has aroused intense interest with the best overall performance in adverse weather and atmospheric turbulence. Meanwhile, a quantum ratchet infrared photodetector (QRIP), ensuring an ultrabroadband photocurrent spectrum at wavelengths ranging from near-infrared to THz (1–75 μ m), was recently proposed to acquire a potential broadband photon-type detection including the VLWIR regime. However, the limited VLWIR responsivity obstructs further applications of GaAs-based ratchet structures. Exploiting metal-dielectric-metal resonant cavities, we demonstrate that the broadband coupling efficiency theoretically achieves a 20-fold enhancement across the 16–20 μ m VLWIR range compared to the mesa reference device. This improvement leads to a significant elevation in responsivity (achieving a peak value of 1.18 AW −1 ), concurrently reducing the noise equivalent power to a minimum of 0.6 pWHz −1/2 and increasing the specific detectivity to a peak of 8.26 × 10 10 Jones. Through theoretical simulations, we reveal that the broadband enhancement can be attributed to the geometric structure of the diagonal-placing patchwork antenna, which not only restricts the light field within the double-metal region but also leads to an effective modulation of patch sizes to broaden the enhancement coverage. Our discovery evidences efficient arrayed spacing-perturbed antennas for the high-performance QRIP which can be modified to capture not only VLWIR but also IR/THz electromagnetic signals.