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Optical nonlinearities in chemically synthesized and femtosecond laser fabricated gold nanoparticle colloidal solutions

Optical nonlinearities in chemically synthesized and femtosecond laser fabricated gold nanoparticle colloidal solutions
Optical nonlinearities in chemically synthesized and femtosecond laser fabricated gold nanoparticle colloidal solutions
Gold nanoparticles prepared by two different methodologies, wet-chemical- citrate reduction synthesis and femtosecond laser ablation, are studied for optical nonlinearities. Femtosecond laser pulses at 800 nm wavelength are employed to study the optical nonlinear refraction and absorption through the Z-scan technique, up to 23.37 GW/cm2 laser intensities. Here we demonstrate the distinct crossovers of nonlinear absorption, from varieties of nonlinear absorption mechanisms, saturation of linear absorption, reverse saturation of absorption. The reverse saturation of absorption is primarily contributed by an initial two-photon absorption followed by three-photon absorption process. We could observe that in laser-ablated gold nanoparticles, the transition from saturable to reverse saturable absorption takes place at a lower excitation threshold compared to that in chemically produced samples. The nonlinear refraction data depicted a pronounced asymmetry for chemically synthesized samples, which could possibly be due to the dominance of absorption phenomenon. We observed that nonlinear refractive index of chemically produced samples is higher by one order of magnitude compared to those produced by laser ablation. An appealing application in optical limiting is studied, and we see that the laser-produced samples, due to their strong nonlinear absorption, serve as a suitable choice for the optical limiting application. This study provides an insight into the selection of synthesis method towards their optimized utilization in nonlinear optical domain given that we achieve particle size tunability in the two methods.
Gold nanoparticles, Nonlinear absorption, Nonlinear refraction, Saturation of absorption, Z-scan technique
0030-3992
Priyadarshini, Mani
07805379-b963-46cd-85d9-6ee2f3ed6e4b
Acharyya, Jitendra Nath
197b53b7-2921-4280-a14f-fb2c736dc502
Mahajan, Sumeet
b131f40a-479e-4432-b662-19d60d4069e9
Prakash, G. Vijaya
7666ac65-1dc4-46c5-9d92-9a0faec90dc2
Priyadarshini, Mani
07805379-b963-46cd-85d9-6ee2f3ed6e4b
Acharyya, Jitendra Nath
197b53b7-2921-4280-a14f-fb2c736dc502
Mahajan, Sumeet
b131f40a-479e-4432-b662-19d60d4069e9
Prakash, G. Vijaya
7666ac65-1dc4-46c5-9d92-9a0faec90dc2

Priyadarshini, Mani, Acharyya, Jitendra Nath, Mahajan, Sumeet and Prakash, G. Vijaya (2021) Optical nonlinearities in chemically synthesized and femtosecond laser fabricated gold nanoparticle colloidal solutions. Optics & Laser Technology, 139, [107008]. (doi:10.1016/j.optlastec.2021.107008).

Record type: Article

Abstract

Gold nanoparticles prepared by two different methodologies, wet-chemical- citrate reduction synthesis and femtosecond laser ablation, are studied for optical nonlinearities. Femtosecond laser pulses at 800 nm wavelength are employed to study the optical nonlinear refraction and absorption through the Z-scan technique, up to 23.37 GW/cm2 laser intensities. Here we demonstrate the distinct crossovers of nonlinear absorption, from varieties of nonlinear absorption mechanisms, saturation of linear absorption, reverse saturation of absorption. The reverse saturation of absorption is primarily contributed by an initial two-photon absorption followed by three-photon absorption process. We could observe that in laser-ablated gold nanoparticles, the transition from saturable to reverse saturable absorption takes place at a lower excitation threshold compared to that in chemically produced samples. The nonlinear refraction data depicted a pronounced asymmetry for chemically synthesized samples, which could possibly be due to the dominance of absorption phenomenon. We observed that nonlinear refractive index of chemically produced samples is higher by one order of magnitude compared to those produced by laser ablation. An appealing application in optical limiting is studied, and we see that the laser-produced samples, due to their strong nonlinear absorption, serve as a suitable choice for the optical limiting application. This study provides an insight into the selection of synthesis method towards their optimized utilization in nonlinear optical domain given that we achieve particle size tunability in the two methods.

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Manuscript JOLT_Rev_fin - Accepted Manuscript
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More information

Accepted/In Press date: 8 February 2021
e-pub ahead of print date: 24 February 2021
Published date: July 2021
Keywords: Gold nanoparticles, Nonlinear absorption, Nonlinear refraction, Saturation of absorption, Z-scan technique

Identifiers

Local EPrints ID: 448424
URI: http://eprints.soton.ac.uk/id/eprint/448424
ISSN: 0030-3992
PURE UUID: bfa52592-6e32-4ad7-8b13-76e6dd6e89c4
ORCID for Sumeet Mahajan: ORCID iD orcid.org/0000-0001-8923-6666

Catalogue record

Date deposited: 22 Apr 2021 16:30
Last modified: 23 Apr 2021 01:39

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Contributors

Author: Mani Priyadarshini
Author: Jitendra Nath Acharyya
Author: Sumeet Mahajan ORCID iD
Author: G. Vijaya Prakash

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