Regensburg 2019 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Two-dimensional Materials I (joint session HL/CPP)

CPP 21.8: Talk

Tuesday, April 2, 2019, 11:30–11:45, H36

Electromagnetically induced transparency in second-harmonic generation from monolayer WSe2 — •Kai-Qiang Lin, Robert Martin, Sebastian Bange, and John Lupton — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93053 Regensburg, Germany

Electromagnetically induced transparency (EIT) occurs in atomic systems and shows versatile applications in slow-light generation, gain without inversion and optical quantum-information processing. We demonstrate a cavity-free, atomic-like EIT effect in single-layer crystals of WSe2, probed by exploiting the intrinsic second-harmonic generation (SHG) arising from the breaking of inversion symmetry.[1] Under conditions of double resonance of the driving and radiated field with the fundamental transitions, the SHG spectrum bifurcates. The feature follows a pump-wavelength-dependent spectral anticrossing, accurately described by a ladder-type three-level model. Crucially, the SHG power-law exponent diverges from the canonical value of 2 to follow a Fano-like dispersion with wavelength. This dispersion is retained at room temperature, implying persistence of quantum interference. Our work opens up opportunities to exploit quantum nonlinear optics such as inversionless gain in the solid state.

[1]. K.-Q. Lin, S. Bange and J. M. Lupton, Nature Physics, in press. (preprint: https://arxiv.org/abs/1811.09479)