Ultrafast nonlinear absorption of TMDC quantum dots

Journal Article · Thu Apr 07 00:00:00 EDT 2022 · Physica. E, Low-Dimensional Systems and Nanostructures

DOI:https://doi.org/10.1016/j.physe.2022.115239· OSTI ID:1977551

Hossaini, S. J. ^[1]; Ghimire, R. ^[1]; Apalkov, V. ^[1]

---

1. Georgia State Univ., Atlanta, GA (United States)

Here, we study theoretically absorption properties of MoS₂ quantum dots placed in an ultrashort and strong optical pulse with the duration of a few femtoseconds and the amplitude up to 1.5 V/Å. While the monolayer of MoS₂ has a bandgap of ≈ 1.8 eV, the quantum dots of MoS₂ have in-gap edge states, which open additional absorption channels. The absorbance of the system strongly depends on the amplitude of the pulse. At small amplitude, less than 0.5 V/Å, the absorbance varies by more than 20% with the frequency of the pulse. The system shows saturable absorption if the frequency of the pulse is larger than the bulk bandgap and reverse saturable absorption if the frequency of the pulse is in the bandgap. At large amplitudes, > 0.5 V/Å, of the pulse, the ultrafast absorbance of a quantum dot has a weak dependence on the pulse frequency. If the frequency of the pulse is less than the corresponding bulk bandgap, the absorbance has a nonmonotonic dependence on the pulse amplitude with the maximum at ≈ 0.5 V/Å. We also present the results for QDs of different TMDC materials, which show that at large field amplitude, > 0.5 V/Å, the absorbance is universal and has weak dependence on the type of TMDC.

• Research Organization: Georgia State Univ., Atlanta, GA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: FG02-01ER15213; SC0007043
• OSTI ID: 1977551
• Journal Information: Physica. E, Low-Dimensional Systems and Nanostructures, Vol. 142, Issue C; ISSN 1386-9477
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
TMDC quantum dots
Ultrafast absorption
Ultrastrong optical pulse
Nonlinear dynamics