Abstract
We report on a nano-optical imaging study of WSe2 thin flakes with scanning near-field optical microscopy (NSOM). The NSOM technique allows us to visualize in real space various waveguide photon modes inside WSe2. By tuning the excitation laser energy, we are able to map the entire dispersion of these waveguide modes both above and below the A exciton energy of WSe2. We found that all the modes interact strongly with WSe2 excitons. The outcome of the interaction is that the observed waveguide modes shift to higher momenta right below the A exciton energy. At higher energies, on the other hand, these modes are strongly damped due to adjacent B excitons or band-edge absorptions. The mode-shifting phenomena are consistent with polariton formation in WSe2.
| Original language | English |
|---|---|
| Article number | 081402 |
| Journal | Physical Review B |
| Volume | 94 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 1 2016 |
Funding
This work was performed, in part, at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility under Contract No. DE-AC02-06CH11357. The work at UW was supported by the U.S. DOE Basic Energy Sciences, Materials Sciences and Engineering Division (DE-SC0008145 and SC0012509). The work at ORNL (JQY and DGM) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.