Giving to CREOL CREOL, The College of Optics & Photonics

COS/CREOL Seminar: “ Mechanism of plasmon excitation and light emission from (molecular) tunneling junctions” by Christian A. Nijhuis

Monday, August 20, 2018 1:30 PM to 2:30 PM
CREOL Room 103

Christian A. Nijhuis
Department of Chemistry
National University of Singapore


To realize nano-scale opto-electronic circuitry, one needs to be able to excite and detect surface plasmon polaritons (SPPs) by electrical means. Tunnel junctions can excite and detect plasmons in a single step without the need for external light sources and optical elements [1-3]. In these devices, currents are directly converted to SPPs in a single step, and vice versa, at tunneling time-scales, and tunnel junctions are widely used in commercial devices. During the talk I will discuss our recent progress in the development of SPPs based on molecular tunnel junctions with self-assembled monolayers (SAMs) or AlOx as the tunnelling barrier [4-10]. By simply applying a bias between the top and bottom electrode, a tunnelling current will which excites a highly confined junction mode, which then can outcouple as single interface SPPs or scattered light.  Since the tunneling direction can be controlled by simply changing the chemical and supramolecular structure of the SAMs (e.g., tilt angle of the SAM via odd-even effects [10]), we have the ability to control the plasmonic properties of the devices and directionally launch plasmons (and the polarization of the emitted photons) [6]. By integrating two tunnel junctions with one plasmonic wave-guide, we demonstrate that the tunnel junctions are also promising as plasmon detectors with plasmon-electron coupling efficiencies of more than 1000 times higher than previous estimates based on photon out coupling rates [8]. Our results show that molecular electronics make it possible to manipulate light at the molecular length-scale and are interesting for applications in plasmonic-electronics in more general.


Christian A. Nijhuis received his Master’s degree in Chemistry from the University of Groningen in 2002, and Ph.D. degree from University of Twente in 2006 (Cum Laude; top 5%). Under the direction of Professor David N. Reinhoudt, his doctoral thesis included studies on the surface chemistry of supramolecular assemblies and their use in bottom-up nano-fabrication. He received the Simon Stevin Research award from the Netherlands Organization for Scientific Research (NWO) in 2006 to conduct overseas research. In the group of Professor George M. Whitesides, as a postdoctoral research fellow, he developed a platform for measurements of charge transport across layers that are one molecule thick. In 2010, he received the NRF research fellowship and he joined the Department of Chemistry at the National University of Singapore as an Assis. Prof. and promoted to Assoc. Prof. in 2016. In 2012, he received the NRF CRP grant to start a new program to develop plasmonic-electronic devices which entered phase II in 2017. He currently uses bottom-up nanofabrication techniques to construct self-assembled nano-electronic devices to study light matter interactions and charge transport across molecular junctions. Other interests include synchrotron based surface characterization, self-assembly, synthesis, 2D materials, and nanoscale dynamics.

For additional information:

Enrique del Barco

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