118
P. Vasa
single SPP mode [8, 9, 70–73]. This regime of vacuum Rabi splitting clearly is much
beyond the two strongly coupled classical oscillators or the semi-classical framework
for the light-matter interaction. The intrinsically quantum mechanical interaction is
expected to offer opportunities to investigate coherent quantum mechanical phenomena on comparatively long length scale and at high temperatures. Two of such phenomena, higher rungs of Jaynes-Cummings ladder and creation of very long lived
states isolated from surroundings are briefly mentioned here. Similar effects have
been observed in semiconductor coupled micro-cavities and super-conducting systems at very low temperatures [4–9]. The biggest challenges are the strong radiative
damping and low coupling energies. Innovative designs of metal nano-antenna and
gap modes have been proposed to enhance the field localization and reduce the damping so as to reach the Rabi energies of several meV. The experimental investigations
discussed here suggest that considerable progress has been made in understanding the
coherent nonlinear response of metal-semiconductor hybrid nanostructures and substantial experimental and theoretical progress seems within the reach with improvements in fabrication techniques, ultrafast spectroscopy, theoretical framework, and
experimental as well as theoretical studies. In general, metal-semiconductor hybrid
nanostructures provide fascinating possibilities to explore various types of vacuum
field induced coherent light-matter interactions at room temperature. Similar investigations were conventionally possible only in very pure atomic systems, high Qfactor microcavities, and superconductors. Due to the plasmonic field enhancement
in metallic nanostructures, substantial intensification of light-matter interaction may
be possible leading to highly efficient ultrafast coherent switching with femtojoule
pulse energies in sub-wavelength structures [41–44]. Ideally, only few or even a
single photon would be sufficient to induce the switching in tailor-designed hybrid
nanoantennas optimized of strong light-matter interaction. Such ultrafast plasmonic
switches and/or transistors would constitute entirely new nano-photonic devices that
could create fundamentally different opportunities for all-optical communication and
computation [74, 75]. These devices might operate at power levels and switching
efficiencies that to date can only be reached with electronic transistors. At the same
time, they might operate at extremely high operation speeds in the Terahertz regime,
in principle only limited by the femtosecond lifetime of coupled or hybrid mode.
Such hybrid exciton/plasmon devices might therefore combine favorable properties
of electronic and all-optical devices and would truly merge plasmonics and quantum
electronics [6, 8, 9, 14].
References
1. M. Born, E. Wolf, Principles of Optics, 7th edn. (Cambridge University Press, Cambridge,
1999)
2. M.O. Scully, M.S. Zubairy, Quantum Optics (Cambridge University Press, Cambridge, 2001)
3. P. Vasa, D. Mathur, Ultrafast Biophotonics (Springer International Publishing, Switzerland,
2016)
4. G.S. Agarwal, Quantum optics, vol. 70 (Springer, New York, 1974)
P. Vasa
single SPP mode [8, 9, 70–73]. This regime of vacuum Rabi splitting clearly is much
beyond the two strongly coupled classical oscillators or the semi-classical framework
for the light-matter interaction. The intrinsically quantum mechanical interaction is
expected to offer opportunities to investigate coherent quantum mechanical phenomena on comparatively long length scale and at high temperatures. Two of such phenomena, higher rungs of Jaynes-Cummings ladder and creation of very long lived
states isolated from surroundings are briefly mentioned here. Similar effects have
been observed in semiconductor coupled micro-cavities and super-conducting systems at very low temperatures [4–9]. The biggest challenges are the strong radiative
damping and low coupling energies. Innovative designs of metal nano-antenna and
gap modes have been proposed to enhance the field localization and reduce the damping so as to reach the Rabi energies of several meV. The experimental investigations
discussed here suggest that considerable progress has been made in understanding the
coherent nonlinear response of metal-semiconductor hybrid nanostructures and substantial experimental and theoretical progress seems within the reach with improvements in fabrication techniques, ultrafast spectroscopy, theoretical framework, and
experimental as well as theoretical studies. In general, metal-semiconductor hybrid
nanostructures provide fascinating possibilities to explore various types of vacuum
field induced coherent light-matter interactions at room temperature. Similar investigations were conventionally possible only in very pure atomic systems, high Qfactor microcavities, and superconductors. Due to the plasmonic field enhancement
in metallic nanostructures, substantial intensification of light-matter interaction may
be possible leading to highly efficient ultrafast coherent switching with femtojoule
pulse energies in sub-wavelength structures [41–44]. Ideally, only few or even a
single photon would be sufficient to induce the switching in tailor-designed hybrid
nanoantennas optimized of strong light-matter interaction. Such ultrafast plasmonic
switches and/or transistors would constitute entirely new nano-photonic devices that
could create fundamentally different opportunities for all-optical communication and
computation [74, 75]. These devices might operate at power levels and switching
efficiencies that to date can only be reached with electronic transistors. At the same
time, they might operate at extremely high operation speeds in the Terahertz regime,
in principle only limited by the femtosecond lifetime of coupled or hybrid mode.
Such hybrid exciton/plasmon devices might therefore combine favorable properties
of electronic and all-optical devices and would truly merge plasmonics and quantum
electronics [6, 8, 9, 14].
References
1. M. Born, E. Wolf, Principles of Optics, 7th edn. (Cambridge University Press, Cambridge,
1999)
2. M.O. Scully, M.S. Zubairy, Quantum Optics (Cambridge University Press, Cambridge, 2001)
3. P. Vasa, D. Mathur, Ultrafast Biophotonics (Springer International Publishing, Switzerland,
2016)
4. G.S. Agarwal, Quantum optics, vol. 70 (Springer, New York, 1974)