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Intrinsic optical nonlinearities and carrier dynamics of InSe

Researchers report intrinsic optical nonlinearities and carrier dynamics of InSe

(a) Schematic of the μ-Z/I scan setup used for the NLO experiment. (bc) The μ-Z open/closed aperture scan results of InSe film. (d) Transient absorption spectrum of InSe flake under a 200 fs pulsed laser excitation at 400 nm. (e) Schematic diagram of the carrier relaxation process. Credit: SIOM

Recently, researchers from the Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences conducted a systematic investigation of the microscopic optical nonlinearities and transient carrier dynamics in Indium Selenide (InSe) Nanosheet. Related research results have been published in: Optics Express on May 9, 2022.

In recent decades, two-dimensional (2D) materials have been widely used in many fields. It is fundamental but important to study the intrinsic features and further realize the controllable modification engineering of these optical and physical properties in 2D materials. InSe, an excellent optoelectronic material, has been studied in nonlinear optics, optoelectronic and biomedicine. However, the intrinsic nonlinear optical properties have not been carefully investigated.

In this work, the researchers prepared a series of InSe nanosheets of different thicknesses by a mechanical exfoliation method and systematically examined the nonlinear optical properties and the broad-spectrum ultrafast carrier dynamics.

The nonlinear optical properties were measured via a home-bulit micro-Z/I scan setup under the excitation of 520 nm and 1040 nm fs pulses. InSe films exhibit two photon absorption effects (TPA effects) under both visible and near infrared light excitation, and the InSe nanosheets are more likely to achieve TPA saturation in the visible range, since the TPA coefficient of InSe is of the same thickness excited by 520 nm is two. orders of magnitude greater than 1040 nm, and Is.520 nm is an order of magnitude less than Is.1040 nm.

Transient absorption spectroscopy measurements showed that InSe films have an ultrafast transition from photoinduced absorption to photobleaching and a rapid relaxation process of ~0.4-1 ps in the visible range.

The systematic study of the intrinsic nonlinear optical properties of InSe nanosheets and ultrafast carrier dynamics provides experimental and theoretical guidelines for the development of InSe-based optoelectronic devices, as well as inspiration for nonlinear optical testing of other two-dimensional materials.

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More information:
Chenduan Chen et al, Microscopic optical nonlinearities and transient carrier dynamics in indium selenide nanosheet, Optics Express (2022). DOI: 10.1364/OE.459023

Provided by the Chinese Academy of Sciences

Quote: Intrinsic Optical Nonlinearities and Carrier Dynamics of InSe (2022, June 16) Retrieved June 16, 2022 from https://phys.org/news/2022-06-intrinsic-optical-nlinearities-carrier-dynamics.html

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