Room Temperature Terahertz Electroabsorption Modulation by Excitons in Monolayer Transition Metal Dichalcogenides
Abstract
The interaction between off-resonant laser pulses and excitons in monolayer transition metal dichalcogenides is attracting increasing interest as a route for the valley-selective coherent control of the exciton properties. Here, we extend the classification of the known off-resonant phenomena by unveiling the impact of a strong THz field on the excitonic resonances of monolayer MoS$_2$. We observe that the THz pump pulse causes a selective modification of the coherence lifetime of the excitons, while keeping their oscillator strength and peak energy unchanged. We rationalize these results theoretically by invoking a hitherto unobserved manifestation of the Franz-Keldysh effect on an exciton resonance. As the modulation depth of the optical absorption reaches values as large as 0.05 dB/nm at room temperature, our findings open the way to the use of semiconducting transition metal dichalcogenides as compact and efficient platforms for high-speed electroabsorption devices.
- Publication:
-
Nano Letters
- Pub Date:
- July 2020
- DOI:
- 10.1021/acs.nanolett.0c01134
- arXiv:
- arXiv:2006.04786
- Bibcode:
- 2020NanoL..20.5214S
- Keywords:
-
- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- 40 pages, 11 figures