Merging photonic structures and optoelectronic sensors into a single chip may yield a sensor‐on‐chip spectroscopic device that can measure the spectrum of matter. In this work, an on‐chip concurrent multiwavelength infrared (IR) sensor, which consists of a set of narrowband wavelength‐selective plasmonic perfect absorbers combined with pyroelectric sensors, where the response of each pyroelectric sensor is boosted only at the resonance of the nanostructured absorber, is proposed and realized. The proposed absorber, which is based on Wood's anomaly absorption from a 2D plasmonic square lattice, shows a narrowband polarization‐independent resonance (quality factor – Q of 73) with a nearly perfect absorptivity as high as 0.99 at normal incidence. The fabricated quad‐wavelength IR sensors exhibit four different narrowband spectral responses at normal incidence following the predesigned resonances in the mid‐wavelength infrared region that corresponds to the atmospheric window. The device can be applied for practical spectroscopic applications such as nondispersive IR sensors, IR chemical imaging devices, pyrometers, and spectroscopic thermography imaging.

In this paper, we prove that indium tin oxide (ITO) can be a material of choice for wavelength-selective thermal emitters that enable operation in ambient air. The wavelength-selective thermal emission is achieved by plasmonic ITO perfect absorbers (IPAs) composed of ITO – Al₂O₃ – ITO tri-layers where the top ITO layer is a hexagonal array of ITO disks. Simulated optical spectra of the IPAs reveal nearly perfect absorptivities (i.e. 0.99) at obvious resonances, which can be easily tuned just by changing the size of the ITO disks. The fabricated IPAs that followed the pre-designed simulation also exhibit excellented resonant absorptivities (i.e. 0.92), as well as good resonance tunability, which indicate the appreciable performance of IPAs. Furthermore, we show that IPAs are also feasible to serve as highly-efficient thermal emitters that can operate in ambient air without the need for strict vacuum or inert gas conditions, providing another platform for IR plasmonic devices.

We propose and experimentally demonstrate a compact design for membrane-supported wavelength-selective infrared (IR) bolometers. The proposed bolometer device is composed of wavelength-selective absorbers functioning as the efficient spectroscopic IR light-to-heat transducers that make the amorphous silicon (a-Si) bolometers respond at the desired resonance wavelengths. The proposed devices with specific resonances are first numerically simulated to obtain the optimal geometrical parameters and then experimentally realized. The fabricated devices exhibit a wide resonance tunability in the mid-wavelength IR atmospheric window by changing the size of the resonator of the devices. The measured spectral response of the fabricated device wholly follows the pre-designed resonance, which obviously evidences that the concept of the proposed wavelength-selective IR bolometers is realizable. The results obtained in this work provide a new solution for on-chip MEMS-based wavelength-selective a-Si bolometers for practical applications in IR spectroscopic devices.

Spectrally selective detection is of crucial importance for diverse modern spectroscopic applications such as multi-wavelength pyrometry, non-dispersive infrared gas sensing, biomedical analysis, flame detection, and thermal imaging. This paper reports a quad-wavelength hybrid plasmonic–pyroelectric detector that exhibited spectrally selective infrared detection at four wavelengths—3.3, 3.7, 4.1, and 4.5 μm. The narrowband detection was achieved by coupling the incident infrared light to the resonant modes of the four different plasmonic perfect absorbers based on Al-disk-array placed on a Al₂O₃–Al bilayer. These absorbers were directly integrated on top of a zinc oxide thin film functioning as a pyroelectric transducer. The device was fabricated using micro-electromechanical system (MEMS) technology to optimize the spectral responsivity. The proposed detector operated at room temperature and exhibited a responsivity of approximately 100–140 mV/W with a full width at half maximum of about 0.9–1.2 μm. The wavelength tunability, high spectral resolution, compactness and robust MEMS-based platform of the hybrid device demonstrated a great advantage over conventional photodetectors with bandpass filters, and exhibited impressive possibilities for miniature multi-wavelength spectroscopic devices.

Ultra-narrowband perfect absorbers and emitters are proposed and realized by engineering multiple-beam interference in Gires-Tournois etalon with the presence of low metallic loss. The absorption mechanism and spectral characteristics of the Gires-Tournois resonators are numerically and experimentally investigated for three configurations: dielectric cavity on metal, metal–dielectric–metal resonator, and distributed Bragg reflector (DBR)–dielectric–metal resonator. Narrowband thermal emitters based on the metal–dielectric–metal cavity and (DBR)–dielectric–metal cavity are experimentally demonstrated with an emissivity of 0.8 and 0.82, and a quality factor of 21 and 85, respectively. A DBR–dielectric–metal resonator-based absorber is directly loaded onto a LiTaO${ }_3$ film for the first time to constitute an on-chip ultra-narrowband pyroelectric detector with an excellent quality factor of 151 at the absorption band of methane.