Dresden 2017 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 67: Perovskites, Hybrid Photovoltaics and Plasmonics
HL 67.2: Talk
Thursday, March 23, 2017, 09:45–10:00, POT 81
Ultrafast photo-switching of hybrid polaritons in black phosphorus heterostructures — •Fabian Sandner1, Markus A. Huber1, Fabian Mooshammer1, Markus Plankl1, Leonardo Viti2, Lukas Z. Kastner1, Tobias Frank1, Jaroslav Fabian1, Miriam S. Vitiello2, Tyler L. Cocker1, and Rupert Huber1 — 1University of Regensburg, 93040 Regensburg, Germany — 2NEST CNR, 56127 Pisa, Italy
In recent years, special attention has been paid to surface polaritonics in van der Waals layered materials and their heterostructures. In particular, graphene has been intensely studied, as it exhibits strongly confined and widely tunable mid-infrared Dirac plasmons. However, the absence of an energy gap inhibits high switching contrasts, which are desired for nano-polaritonic devices. Here, we design and fabricate a SiO2/black phosphorus/SiO2 heterostructure and demonstrate ultrafast switching of a mid-infrared hybrid polariton by femtosecond near-infrared laser excitation. We trace the mode in energy, time, and space using pump-probe near-field microscopy and spectroscopy, providing us with real-space snapshots of the mode as well as its dispersion. In our heterostructure, surface phonons on the SiO2 layers couple to transient surface plasmons on the photoexcited black phosphorus layer. The resulting hybrid interface polariton exhibits exceptional coherence properties and features a well-defined frequency and wavevector for the entire lifetime of the mode. Our results, which can be fully reproduced by theoretical calculations, show that the hybrid mode holds significant potential for future ultrafast nano-optical devices.