99 98 Principal Scientist Profiles Jer-Shing Huang Jer-Shing Huang Principal Scientist Profiles HEAD OF RESEARCH DEPARTMENT OF NANOOPTICS, LEIBNIZ INSTITUTE OF PHOTONIC TECHNOLOGY Dr. Jer-Shing Huang is the head of the Research Department of Nanooptics at the Leibniz Institute of Photonic Technology (Leibniz-IPHT). He is also an adjunct professor at the Department of Electrophysics at National Chiao Tung University (NCTU) and an adjunct research fellow at the Research Center for Applied Sciences (RCAS) at the Academia Sinica in Taiwan. Before Dr. Huang moved to Jena in 2016, he was an associate professor at the Department of Chemistry of National Tsing Hua University in Taiwan. Since 2016, Dr. Huang has been a member of the Editorial Advisory Board of ACS Photonics and SPIE Visiting Lecturer. JER-SHING HUANG RESEARCH AREAS Dr. Huang’s research focuses on the engineering of nanoscale optical fields and light-matter interactions. The research is based on fundamental sciences in physics and chemistry, and extends to interdisciplinary applications in the fields of optics, spectroscopy, microscopy, materials sciences, and sensors. Current research topics include: • Nanoantennas and nanocircuits • Optical trapping • Chiral spectroscopy and imaging • Plasmonic nanosensors • DNA origami-based plasmonic devices • Fluorescent polymer micro-resonators TEACHING FIELDS Dr. Huang’s teaching covers basic and advanced topics for graduate students to gain sufficient knowledge in light-matter interaction. Dr. Huang’s courses include: • Physical chemistry • Analytical chemistry • Instrumental analysis • Light-matter interaction RESEARCH METHODS Dr. Huang’s research group exploits modern computer simulations and nanotechnologies to design and fabricate high-definition nanostructures and applies linear and nonlinear microscopic and spectroscopic methods to characterize the optical response of the nanostructures and study the interaction between light and matter. Specific research methods include: • Numerical simulations (COMSOL and FDTD Solutions) • Microscopy and spectroscopy • E-beam lithography and focused-ion beam milling • Scanning electron and atomic force microscopy • PL and dark-field scattering spectroscopy • Circular-dichroism spectroscopy • Evanescent-wave cavity ring-down spectroscopy RECENT RESEARCH RESULTS The interaction between light and matter is usually limited by the size mismatch between light wavelength and molecular size in the matter. The goal of Dr. Jer-Shing Huang’s group is to understand, control, and utilize nanoscale light-matter interactions through the application of rationally designed nanostructures. In particular, the group focuses on nanoplasmonics, which studies and controls the fundamental processes of the interaction of light with matter at the nanoscale. Fields of application include the sensitive detection of molecular chirality, nanoscale integrated optical circuits, plasmon-enhanced spectroscopy, and nanoobjects manipulation by the optical field. For optical nanosensors, we have developed a spectrometer-free plasmonics sensing platform, the plasmonic Doppler grating (PDG) [1]. A PDG consists of a series of circular grooves on a gold film that mimics the wavefront of a moving point source exhibiting the Doppler effect. We demonstrate PDG’s ultimate sensitivity for direct quantification of the peculiar and tiny refractive index enhancement due to hydrogen bonds in water-ethanol mixtures. The PDG has also been applied to spatially resolve the plasmonic enhancement effect in coherent anti-Stokes Raman scattering [2]. Another type of optical nanosensors are based on bottom-up chemically synthesized nanoparticles. For example, we prepared high-definition bimetallic Au−Pd−Au nanobricks as an archetype of robust nanoplasmonic hydrogen sensors. We achieved the highest spectral shift of the resonance peak upon the absorption of hydrogen gas at a very low concentration [3]. For optical nanocircuits, we developed, for the first time, deep sub-wavelength mode conversion at the frequency of 194 THz (vacuum wavelength =1,545 nm). The field is confined into a nanogap with a width of only λ/15 of the operational optical signals. We show that by controlling the symmetry of the fundamentals modes in the waveguide, second-harmonics can be effectively generated in a centrally symmetric structure made of gold materials. [4]. Regarding chiral light-matter interaction, we have developed a one-step nanofabrication method to effectively fabricate a metasurface consisting of 3D chiral units, which exhibit superior chiral dissymmetry, stable field localization, and broadband near-field optical chirality [5]. We also study the generation of optical chirality patterns using interference of far-field beam and plasmonic waves [6]. These optical chirality patterns have many potential applications including super-resolution chiral imaging [7]. Figure 1 shows the representative images from the mentioned research projects. BROADBAND DIRECTIONAL TRANSMITTING OPTICAL NANOANTENNAS OPERATING AT 400 THZ Optical nanoantennas for next-generation wireless communication in the visible range (400-750 THz) feature a miniaturized footprint and ultrahigh operational frequency. The realization of broadband and directional transmitting optical nanoantennas with tunability is, however, technically challenging because multiple emitters at different wavelengths need to be precisely positioned at different antenna elements separated only by ~100 nm. This renders the implementation of “transmitting” directional nanoantennas very difficult. Recently, we have successfully overcome this challenge by exploiting the photoluminescence from the antenna material as a unique optical source to drive the nanoantenna. We experimentally demonstrated broadband directional transmitting nanoantennas operating at frequencies higher than 400 THz (λ = 750 nm). The opportunity of using photoluminescence from the antenna’s material as the power source is unique for optical nanoantennas and finds no counterparts in their RF counterparts. The significance is not only about wireless communication at ultrahigh frequency but also that the operational frequency enters the regime of electronic transition in typical materials, allowing for the manipulation of light-matter interaction. Figure 1. Graphical summary of selected research results. Figure 2. Broadband directional optical nanoantennas driven by photoluminescence of gold. [1] Lin et al., Anal. Chem. 91, 9382 (2019). [2] Ouyang et al., ACS Nano doi:10.1021/acsnano.0c07198 (2021). [3] Ng et al., Chem. Mater. 30, 204 (2018). [4] Chen et al., Nano Lett. 19, 6424 (2019). [5] Tseng et al., Adv. Opt. Mater. 7, 1900617 (2019). [6] Zhang et al., Opt. Express 28, 760 (2020). [7] Huang et al., ACS Photon., DOI:10.1021/acsphotonics.0c01360 (2021). Contact: Phone: +49 3641 2 06404 Email: jer-shing.huang@leibniz-ipht.de
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