Dynamically reconfigurable subwavelength optical device for hydrogen sulfide gas sensing

Abstract

The importance of tunable subwavelength optical devices in modern electromagnetic and photonic systems is indisputable. Herein, a lithography-free, wide-angle, and reconfigurable subwavelength optical device with high tunability operating in the near-infrared regions is proposed and experimentally demonstrated, based on a reversible nanochemistry approach. The reconfigurable subwavelength optical device basically comprises an ultrathin copper oxide (CuO) thin film on an optical thick gold substrate by utilizing the reversible chemical conversion of CuO to sulfides upon exposure to hydrogen sulfide gas. Proof-of-concept experimental results show that the maximal modulation depth of reflectance can be as high as 90% at the wavelength of 1.79 μm with the initial thickness of CuO taken as 150 nm. Partially reflected wave calculations combined with the transfer matrix method are employed to analytically investigate the optical properties of the structure, which show good agreement with experimental results. We believe that the proposed versatile approaches can be implemented for dynamic control management, allowing applications in tunable photonics, active displays, optical encryption, and gas sensing.

Tailoring the Vertical and Planar Growth of 2D WS2 Thin Films Using Pulsed Laser Deposition for Enhanced Gas Sensing Properties

“…Gas sensing is optimized with high surface-to-volume ratios and increased numbers of active sites in the transducer material. This is achieved by employing either a specific growth process or postsynthesis treatments like increasing the amount of grain boundaries, synthesizing porous structures, doping, ion irradiation, plasma treatment, etc. − A gas sensor uses multiple transduction mechanisms with chemoresistive, FET, optical, and electrochemical device architectures. − However, the chemoresistive gas sensing is widely used due to its simple and low-cost device architecture.…”

High color saturation and angle-insensitive ultrathin color filter based on effective medium theory

“…A typical thin-film configuration to realize large-scale and angle-insensitive color filters is the metal-dielectric-metal (MDM) Fabry-Perot (FP) resonator that consists of a dielectric layer sandwiched between two metallic layers [11][12][13] . To further realize ultrathin devices, a simple thin-film structure composed of a dielectric layer made of high-refractive-index lossy materials such as CuO, SiC, a-Si, and a metallic substrate has been recently reported to generate reflective colors [14][15][16][17] . It is worth pointing out that the thickness of the lossy dielectric layer is generally tens of nanometers, which is much thinner than the dielectric layer with hundreds of nanometers in the conventional MDM structure.…”

Ultra-thin midwavelength infrared absorber using bismuth based planar thin film metamaterials

“…A large portion of electromagnetic radiation in this band can transmit directly through the Earth's atmosphere without any distortion or absorption. 1) In this context, great efforts have been made to develop perfect absorbers operating in the MWIR regime, which could inspire a vast variety of potential applications including thermal photovoltaics, 2) thermal bolometers, 3) infrared sensing, 4) infrared camouflage, 5,6) infrared photodetector, 7) radiative cooling, 8) and thermal emitters, 9,10) etc. For these purposes, many nanostructured optical systems were developed in various sizes, shapes and architectures to attain perfect absorbers, [11][12][13][14][15][16][17][18][19][20] such as plasmonic metasurfaces, optical cavities, metallic gratings and photonic crystals.…”