Plasmon-induced thermal tuning of few-exciton strong coupling in 2D atomic crystals
Lin Liu, Landobasa Y. M. Tobing, Tingting Wu, Bo Qiang, F. J. García‐Vidal, Dao Hua Zhang, Qi Jie Wang, Yu Luo
Abstract
Strong light–matter interaction in 2D materials at the few-exciton level is important for both fundamental studies and quantum optical applications. Characterized by a fast coherent energy exchange between photons and excitons, strongly coupled plasmon–exciton systems in 2D materials have been reported with large Rabi splitting. However, large Rabi splitting at the few-exciton level generally requires large optical fields in a highly confined mode volume, which are difficult to achieve for in-plane excitons in 2D materials. In this work, we present a study of a strongly coupled gold dimer antenna with a sub-10 nm gap on a monolayer tungsten disulphide ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">W</mml:mi> <mml:mi mathvariant="normal">S</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> ), with an estimated number of excitons of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>4.67</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.99</mml:mn> </mml:math> . We demonstrate that varying the spatial mode overlap between the plasmonic field and the 2D material can result in up to a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∼</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">t</mml:mi> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> <mml:mi mathvariant="normal">o</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> <mml:mi mathvariant="normal">d</mml:mi> </mml:mrow> </mml:math> increase in the number of excitons, a value that can be further actively tuned via plasmon-induced heating effects. The demonstrated results would represent a key step toward quantum optical applications operating at room temperatures.