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Plasmonic Organic Hybrid Modulators—Scaling Highest Speed Photonics to the Microscale

Haffner, Christian, et al. “Plasmonic organic hybrid modulators—scaling highest speed photonics to the microscale.” Proceedings of the IEEE 104.12 (2016): 2362-2379.


Complementing plasmonic slot waveguides with highly nonlinear organic materials has rendered a new generation of ultracompact active nanophotonic components that are redefining the state of the art. In this paper, we review the fundamentals of this so-called plasmonic- organic-hybrid (POH) platform. Starting from simple phase shifters to the most compact IQ modulators, we introduce key devices of high-speed data communications. For instance, all-plasmonic Mach-Zehnder modulators (MZMs) are reviewed and long-term prospects are discussed. This kind of modulator already features unique properties such as a small footprint (<; 20 μm 2 ), a large electro-optic bandwidth (> 110 GHz), a small energy consumption (~25 fJ/b), a large extinction ratio (> 25 dB) in combination with a record small voltage-length product of 40 Vμm. Finally, as an example for seamless integration we introduce novel plasmonic IQ modulators. With such modulators we show the generation of advanced modulation formats (QPSK, 16-QAM) on footprints as small as 10 μm × 75 μm. This demonstration ultimately shows how plasmonics can be used to control both phase and amplitude of an optical carrier on the microscale with reasonably low losses.

Artistic view of different organic modulator technologies. (a) Organic waveguide modulators. Light (optical mode profile) is guided within a waveguide formed by the organic NLO material; the phase is modulated by the applied drive voltage USignal and drops off over the distance of a few micrometers as indicated by the radio-frequency (RF) field (gray). Such organic modulator devices have centimeter lengths. (b) SOH modulators have submillimeter lengths. Here, the electrical field drops only over the slot filled with the organic material. However, the performance is still limited as the diffraction limit forbids complete confinement of light to the slot. (c) This can be overcome by the POH approach, which is not diffraction limited and enables modulator lengths of only several micrometers.