Affiliation:
1. Indian Institute of Science Education and Research Bhopal
Abstract
In this Letter, we report the third-order absorptive and refractive nonlinear optical response of highly luminescent WS2 quantum dots (QDs) in the off-resonant femtosecond and nanosecond pulses, which is beneficial for optical limiting and quantum information processing. For 800 nm femtosecond excitation, QDs show two-photon absorption (β = (107 ± 2)×10−3 cm/GW) with positive nonlinearity originating from bound carriers. This picture changes significantly for 532 nm nanosecond excitation, where it shows reverse saturable absorption with negative nonlinearity primarily originating from the sequential absorption of two single photons through the shallow defects, creating free carriers. Our results provide a promising route toward low-dimensional optoelectronic devices.
Funder
Science and Engineering Research Board
Department of Science and Technology, Ministry of Science and Technology, India
Subject
Atomic and Molecular Physics, and Optics
Cited by
3 articles.
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