Abstract-Extreme ultraviolet plasmonics and Cherenkov radiation in silicon

Prashant Shekhar, Sarang Pendharker, Harshad Sahasrabudhe, Douglas Vick, Marek Malac, Rajib Rahman, and Zubin Jacob

https://www.osapublishing.org/optica/abstract.cfm?URI=optica-5-12-1590

Silicon is widely used as the material of choice for semiconductor and insulator applications in nanoelectronics, micro-electro-mechanical systems, solar cells, and on-chip photonics. In stark contrast, in this paper, we explore silicon’s metallic properties and show that it can support propagating surface plasmons, collective charge oscillations, in the extreme ultraviolet (EUV) energy regime not possible with other plasmonic materials such as aluminum, silver, or gold. This is fundamentally different from conventional approaches, where doping semiconductors is considered necessary to observe plasmonic behavior. We experimentally map the photonic band structure of EUV surface and bulk plasmons in silicon using momentum-resolved electron energy loss spectroscopy. Our experimental observations are validated by macroscopic electrodynamic electron energy loss theory simulations as well as quantum density functional theory calculations. As an example of exploiting these EUV plasmons for applications, we propose a tunable and broadband thresholdless Cherenkov radiation source in the EUV using silicon plasmonic metamaterials. Our work can pave the way for the field of EUV plasmonics.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Transparent subdiffraction optics: nanoscale light confinement without metal

Saman Jahani and Zubin Jacob  »View Author Affiliations

 http://www.opticsinfobase.org/optica/abstract.cfm?uri=optica-1-2-96

Optica, Vol. 1, Issue 2, pp. 96-100 (2014)
http://dx.doi.org/10.1364/OPTICA.1.000096

The integration of nanoscale electronics with conventional optical devices is restricted by the diffraction limit of light. Metals can confine light at the subwavelength scales needed, but they are lossy, while dielectric materials do not confine evanescent waves outside a waveguide or resonator, leading to cross talk between components. We show that light can be confined below the diffraction limit using completely transparent artificial media (metamaterials with ε>1, μ=1). Our approach relies on controlling the optical momentum of evanescent waves—an important electromagnetic property overlooked in photonic devices. For practical applications, we propose a class of waveguides using this approach that outperforms the cross-talk performance by 1 order of magnitude as compared to any existing photonic structure. Our work overcomes a critical stumbling block for nanophotonics by completely averting the use of metals and can impact electromagnetic devices from the visible to microwave frequency ranges.

© 2014 Optical Society of America