Subsequent projects
Prof. Dr. Ulf Peschel
Friedrich-Alexander-University
of Erlangen-Nuremberg
Institute of Optics, Information and Photonics
Prof. Dr. Harry A. Atwater
California Institute of Technology, Pasadena (CALTECH)
Engineering & Appl. Science Division
Active and advanced functionalities in ultracompact plasmonic nanocircuits
Plasmonics enables the miniaturization of photonic components to size scales below the Abbe diffraction limit. In the initial project, our groups at the FAU Erlangen and at Caltech have jointly developed plasmonic nanocircuits for the unprecedentedly compact guiding of light and connected optical antennas for efficient probing with a highly focused laser beam (Kriesch et al. Nano Lett. 2013). In the extended project we now investigate additional functionalities and physical phenomena in those circuits.
Based on our first demonstration of a subwavelength electro-plasmonic modulator (PlasMOStor, Lee et al. Nano Lett. 2014) we now implement the investigated transparent conductive oxide to other functional nanocircuit units whose properties can be tuned by external charge-carrier injection. We investigate negative refraction within the framework of the developed nanocircuits, including a two-dimensional realization of super-resolution imaging and we work on wavelength-scale nanocircuits with multiple antenna-ports that can act as resonant guided wave networks (RWGN), a form of versatile wavelength-filter-units by design of resonant, interconnected cavities.
Primary project: Silicon compatible plasmonic nanocircuitry with embedded subwavelength waveguides
Final Report
We continued to develop, fabricate and experimentally test novel dielectric-embedded plasmonic nanocircuits with subwavelength confinement (350 nm < λ0 = 1550 nm), while maintaining low loss (fabrication at CALTECH, measurements at FAU) in particular plasmonic waveguide arrays [1]. Excited via Yagi-Uda-nanoantennas those arrays showed negative coupling and consequently negative refraction, which we could demonstrate in several experiments.
Further activities comprised the realization of a zero index waveguides, which we excited via a particularly designed nano-antenna. We could experimentally realize Young’s double slit experiment in this artificial environment. We also observed enhanced back-scattering and an amplification of scattering by imperfections close to the zero index cut-off of the waveguide [2,3].
Our activities in plasmonics also comprised the design and modelling of cone shaped titania nanotube films for photovoltaic applications. We could show that the enhanced efficiency of these structure is based on an index matching effect, which allows the light to enter much deeper into the solar cell resulting in an improved absorption and thus enhanced electrical power generation [4].
Our activities included several mutual visits, e.g. of Arian Kriesch and Daniel Ploß at CALTECH in Stanford.
Project-publications:
[1] A. Kriesch, H. W. H. Lee, D. Ploss, S. P. Burgos, H. Pfeifer, J. Naeger, H. A. Atwater and U. Peschel, “Negative refraction due to discrete plasmon diffraction,” CLEO 2015, San Jose, USA (2015). oral
[2] D. Ploss, A. Kriesch, J. Naeger, and U. Peschel, “Epsilon-near zero wave diffraction in the optical domain,” CLEO 2015, San Jose, USA (2015). oral
[3] D. Ploss, A. Kriesch, C. Etrich, N. Engheta, and U. Peschel, ”Young's Double-Slit, Invisible Objects and the Role of Noise in an Optical Epsilon-near-Zero Experiment,” ACS Photonics 4, 2566-2572 (2017).
[4] S. So, A. Kriesch, U. Peschel, and P. Schmuki, “Conical-shaped titania nanotubes for optimized light management in DSSC reach back-side illumination efficiency > 8%,” Journal of Material Chemistry A, pp. 12603-12608 (2015)