2, Department of Condensed Matter Physics, Hokkaido University, Sapporo, Hokkaido, Japan
Wavelength-selective light absorbers and emitters, or spectroscopic energy transducers for light, are expected to provide wide variety of applications in energy harvesting, remote sensing, and label free bio-sensing. By utilizing the strong near field of optical antennas and metamaterials, strong signal enhancement of molecules becomes operative to realize high sensitivity vibrational sensing. Recent developments in infrared plasmonic materials, nanostructure fabrication techniques, as well as their surface functionalization techniques have enabled us to propose and fabricate various types of advanced nano-sensing devices. In this talk, we exemplify the detection of tiny amount of molecules by surface-enhanced infrared absorption spectroscopy, using Al infrared antennas and metamaterials. We also introduce our new approach utilizing infrared surface plasmons in optical antenna array made of phosphonic acid-functionalized ITO nanorods to detect proteins with high specificity and sensitivity. In the latter half of the talk, we introduce some of our recently developed uncooled infrared sensors combined with spectroscopic perfect absorbers for wavelength-selective infrared ray detection. The MIM metamaterial IR sensors with pyroelectric detection as well as thermoelectric detection exhibit resolutions better than 1um with wide acceptance angles. By adopting Gires-Turnois structure with plasmonic metals, the wavelength resolution goes lower than 50 nm at resonance wavelength of 3-4 um. Such structures also shows sharp thermal emission when it is fabricated with low-loss materials and heated at high temperatures. These devices will open a new avenue for potential applications in multiband temperature sensing, infrared-color imaging for material sensing, and NDIR gas sesnors for security gas sensors and combustion analysis.
 T.D. Dao, S. Ishii, T. Yokoyama, T. Sawada, S. Ramu Pasupathi, K. Chen, Y. Wada, T. Nabatame, T. Nagao,? ACS Photonics?3, 1271-1278 (2016).
 T. Yokoyama, T. D. Dao, K. Chen, S. Ishii, R. P. Sugavaneshwar, M. Kitajima, T. Nagao, Adv. Opt. Mater. 4 (12), 1987-1992 (2016).
 Kai Chen, Peijun Guo, Thang Duy Dao, Shi-Qiang Li, Satoshi Ishiii,?Tadaaki Nagao, Robert P. H. Chang,? Advanced Optical Materials?5?, 1700091-1?(2017).