Abstract
Two-photon spectroscopy is an important tool for detection of states that are dark in single-photon spectra. We calculate two-photon absorption spectra for monolayer transition-metal dichalcogenides including excitonic effects based on a Bethe-Salpeter equation approach. Both spin-orbit coupling and trigonal warping are included. Our results reveal that otherwise dark p states dominate the two-photon response. However, weakly allowed two-photon transitions coinciding with single-photon s-state resonances appear due to trigonal warping. The angular momentum character of participating excitons is analyzed and we study the sensitivity to screening by dielectric surroundings and discuss the free-carrier limit. Biexciton contributions to the high-energy two-photon response are estimated using a simplified Wannier approach. Finally, a brief comparison with recent experiments is given.
| Original language | English |
|---|---|
| Article number | 085431 |
| Journal | Physical Review B |
| Volume | 104 |
| Issue number | 8 |
| ISSN | 2469-9950 |
| DOIs | |
| Publication status | Published - 15 Aug 2021 |
Bibliographical note
Funding Information:The Center for Nanostructured Graphene is sponsored by the Danish National Research Foundation, Project No. DNRF103.
Publisher Copyright:
© 2021 American Physical Society.