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Near-field resonant photon sorting applied: dual-band metasurface quantum well infrared photodetectors for gas sensing

2020; De Gruyter; Volume: 9; Issue: 16 Linguagem: Inglês

10.1515/nanoph-2020-0456

2192-8606

Mel F. Hainey, Takaaki Mano, Takeshi Kasaya, Tetsuyuki Ochiai, Hirotaka Osato, Kazuhiro Watanabe, Yoshimasa Sugimoto, Takuya Kawazu, Yukinaga Arai, Akitsu Shigetou, Hideki T. Miyazaki,

Spectroscopy and Laser Applications

Abstract Two photodetectors for measuring transmission and two bulky, separated narrowband filters for picking a target gas absorption line and a non-absorbing reference from broadband emission are typically required for dual-band non-dispersive infrared (NDIR) gas sensing. Metal-dielectric-metal (MDM) metasurface plasmon cavities, precisely controllable narrowband absorbers, suggest a next-generation, nanophotonic approach. Here, we demonstrate a dual-band MDM cavity detector that consolidates the function of two detectors and two filters into a single device by employing resonant photon sorting-a function unique to metasurfaces. Two MDM cavities sandwiching a quantum well infrared photodetector (QWIP) with distinct resonance wavelengths are alternately arranged in a subwavelength period. The large absorption cross section of the cavities ensures ~95% efficient lateral sorting of photons by wavelength into the corresponding detector within a near-field region. The flow of incident photons is thus converted into two independent photocurrents for dual-band detection. Our dual-band photodetectors show competitive external quantum efficiencies up to 38% (responsivity 2.1 A/W, peak wavelength 6.9 5m) at 78 K. By tailoring one resonance to an absorption peak of NO 2 (6.25 5m) and the other to a non-absorbing reference wavelength (7.15 5m), NDIR NO 2 gas sensing with 10 ppm accuracy and 1 ms response times is demonstrated. Through experiment and numerical simulation, we confirm near-perfect absorption at the resonant cavity and suppressed absorption at its non-resonant counterpart, characteristic of resonant photon sorting. Dual-band sensing across the mid-infrared should be possible by tailoring the cavities and quantum well to desired wavelengths.