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 NO2 (6.25 5m) and the other to a non-absorbing reference wavelength (7.15 5m), NDIR NO2 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.

中文翻译：

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近场共振光子分选应用：用于气体传感的双波段超表面量子阱红外光电探测器

摘要 双波段非色散红外 (NDIR) 气体传感通常需要两个用于测量透射率的光电探测器和两个用于从宽带发射中挑选目标气体吸收线和非吸收参考的笨重、分离的窄带滤波器。金属-电介质-金属 (MDM) 超表面等离子体腔，可精确控制的窄带吸收器，提出了下一代纳米光子方法。在这里，我们展示了一种双波段 MDM 腔检测器，该检测器通过采用共振光子分类（超表面独有的功能）将两个检测器和两个滤波器的功能整合到单个设备中。两个 MDM 腔夹着一个具有不同共振波长的量子阱红外光电探测器 (QWIP)，在一个亚波长周期中交替排列。腔体的大吸收截面确保了约 95% 的光子按波长横向分选到近场区域内的相应检测器中。因此，入射光子流被转换为两个独立的光电流，用于双波段检测。我们的双波段光电探测器在 78 K 下显示出高达 38%（响应度 2.1 A/W，峰值波长 6.9 5m）的有竞争力的外部量子效率。 - 吸收参考波长 (7.15 5m)，NDIR NO2 气体传感具有 10 ppm 的精度和 1 ms 的响应时间。通过实验和数值模拟，我们确认了谐振腔处近乎完美的吸收，并抑制了其非谐振对应处的吸收，这是谐振光子分选的特征。