Brian S. Dennis, Michael Haftel, David Czaplewski, Daniel Lopez, Girsh Blumberg, Vladimir Aksyuk
The miniaturization of photonic devices is fundamentally limited by the index of refraction of the constituent materials if light is confined in dielectric nanostructures. By coupling electromagnetic fields to metal's free electrons plasmonic devices achieve much deeper localization scaling with the device geometric size. However, when localization compares to the metal skin depth, a large fraction of the energy is shifted from the dielectric into the metal, making active modulation more challenging. Here we propose a scalable phase modulation principle combining metal-insulator-metal gap plasmons (GP) with nanomechanics. We demonstrate a prototype modulator exploiting the extraordinarily large coupling between an electrostatically actuated gap and the phase velocity of tightly confined GPs. The 280 nm gap, 23 micrometer long non-resonant device provides 1.5 pi rad modulation with 1.7 dB excess loss. Remarkably, analysis shows that > pi rad modulation range can be preserved without increasing loss, while scaling the device size down by more than an order of magnitude, because the coupling increases in smaller gaps at least as fast as the loss. A realizable 20 nm gap modulator with a < 1 micormeter^2 footprint can enable complex on-chip optical functions, such as reconfigurable flat plasmonic optics and compact switching fabrics directly integrated with low voltage CMOS.
, Haftel, M.
, Czaplewski, D.
, Lopez, D.
, Blumberg, G.
and Aksyuk, V.
Compact Nano-Mechanical Plasmonic Phase Modulators, Nature Photonics, [online], https://doi.org/10.1038/nphoton.2015.40, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917155
(Accessed February 23, 2024)