Christian Haffner 1 , Daniel Chelladurai 1 , Yuriy Fedoryshyn 1 , Arne Josten 1 , Benedikt Baeuerle 1 , Wolfgang Heni 1 , Tatsuhiko Watanabe 1 , Tong Cui 1 , Bojun Cheng 1 , Soham Saha 3 , Delwin L. Elder 2 , Larry. R. Dalton 2 , Alexandra Boltasseva 3 , Vladimir Shalaev 3 , Nathaniel Kinsey 4 , Juerg Leuthold 1
25 April 2018
For nearly two decades, the field of plasmonics 1 - which studies the coupling of electromagnetic waves to the motion of free electrons in a metal 2 - has sought to realize subwavelength optical devices for information technology 3– 6, sensing 7, 8, nonlinear optics 9, 10, optical nanotweezers 11 and biomedical applications 12. Although the heat generated by ohmic losses is desired for some applications (e.g. photo-thermal therapy), plasmonic devices for sensing and information technology have largely suffered from these losses inherent to metals 13. This has led to a widespread stereotype that plasmonics is simply too lossy to be practical. Here, we demonstrate that these losses can be bypassed by employing “resonant switching”. In the proposed approach, light is only coupled to the lossy surface plasmon polaritons in the device’s off-state (in resonance) where attenuation is desired to ensure large extinction ratios and facilitate sub-ps switching. In the on state (out of resonance), light is prevented from coupling to the lossy plasmonic section by destructive interference. To validate the approach, we fabricated a plasmonic electro-optic ring modulator. The experiments confirm that low on-chip optical losses (2.5 dB), high-speed operation (>>100 GHz), good energy efficiency (12 fJ/bit), low thermal drift (4‰ K -1), and a compact footprint (sub- λ radius of 1 μm) can be realized within a single device. Our result illustrates the potential of plasmonics to render fast and compact on-chip sensing and communications technologies.