Nanosecond light-induced transient absorption in As2S3: Self-trapped exciton recombination in amorphous chalcogenides

Khan, Pritam; Acharja, Prodip; Joshy, Abin; Bhattacharya, Arinjoy; Kumar, Deepak; Adarsh, K. V.

doi:10.1016/j.jnoncrysol.2015.07.002

Cited by 10 publications

(12 citation statements)

References 29 publications

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“…The obtained results are similar to our recent work in As-based ChG films, i.e. As35Se65 [24] and As40S60 [17] and Ge5As30Se65 [ 25] thin films. Consequently, excited state cross section remains higher than ground state cross section and the sample exhibits RSA.…”

Section: Resultssupporting

confidence: 91%

“…In addition to that, ChGs possess high linear refractive index, high third order nonlinear refractive index (n2) and ultrafast response time [16]. ChGs are formed by chalcogen elements (S, Se, Te) in combination with elements like As, Ge, Ga, Sb etc [14,15,17]. Among the family of ChGs, As-based compositions are preferable owing to their high chemical stability.…”

Section: Introductionmentioning

confidence: 99%

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Near resonant nanosecond laser-driven nonlinear optical response in As₅₀S₅₀ thin films

Mandal

Khan

Adarsh

2020

J. Phys. D: Appl. Phys.

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Nanosecond near resonant excitation in As50S50 thin films leads to strong nonlinear optical response, i.e. nonlinear absorption coefficient up to 4 × 10 6 cm/GW and nonlinear refractive index of 8.5 cm 2 /GW, both of which is the strongest ever reported in amorphous semiconductors. We propose a five-level energy model to explain such effect which indicates that nonlinear process is reverse saturable absorption in nature, mediated by excited state absorption from triplet-triplet transition. On the other hand, observation of negative nonlinear refractive index reveals the occurrence of self-defocusing effect. Finally, benefitting from the strong nonlinear response, we demonstrate a promising application of As50S50 thin films as an optical limiter for optoelectronic sensors.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Near resonant nanosecond laser-driven nonlinear optical response in As₅₀S₅₀ thin films

Mandal

Khan

Adarsh

2020

J. Phys. D: Appl. Phys.

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“…5(f) both TA1 (τ1) and TA2 (τ2) decreases with increase in temperature, manifesting that the relaxation process becomes more rapid at higher temperatures, i.e., the relaxation of TA is a thermally activated process which indicates the transient defect states associated with it relaxes immediately at high temperature with the aid of thermal vibration. Similar temperature dependence is also obtained for As2S3 thin films for both 532 and 355 nm, 5ns laser excitation [58].…”

Section: Nanosecond (Ns) Lightinduced Effects In Chgssupporting

confidence: 79%

Lightinduced Effects in Amorphous Chalcogenide Glasses: Femtoseconds to Seconds

Khan¹,

Adarsh²

2021

Preprint

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Amorphous chalcogenide (ChGs) glasses are intrinsically metastable, highly photosensitive, and therefore exhibit numerous lightinduced effects upon bandgap and sub-bandgap illumination. Depending on the pulse duration of the excitation laser, ChGs exhibit a series of lightinduced effects spanning over femtosecond to seconds time domain. For continuous wave illumination, the effects are dominantly metastable in terms of photodarkening (PD) and photobleaching (PB) that takes place via homopolar to heteropolar bond conversion. On the other hand, under nanosecond and ultrafast pulsed illumination, ChGs exhibit transient absorption (TA) that is instigated from the transient bonding rearrangements through self-trapped exciton recombination. In the first part of the review, we pay special attention to continuous wave lightinduced PD and PB, while in the second part we will focus on the TA and controlling such effects via internal and external parameters e.g., chemical composition, temperature, sample history etc.

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“…Here "C" is the chalcogen atom, the super 7 and subscripts denote the charge state and the coordination of the defect states respectively. Such decay processes can be well-understood based on the configurational coordinate diagram [2,31,32] shown in Fig. 2.…”

Section: Resultsmentioning

confidence: 99%

Ultrafast light-induced softening of chalcogenide thin films above the rigidity percolation transition

Khan

Yadav

Adarsh

2018

Journal of Applied Physics

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Little is known about the role of network rigidity in light-induced structural rearrangements in network glasses due to a lack of supporting experiments and theories. In this article, we demonstrate for the first time the ultrafast structural rearrangements manifested as induced absorption (IA) over a broad spectral range in a-GexAs35-xSe65 thin films above the mean-field rigidity percolation transition, quantified by the mean coordination number ⟨r⟩ = 2.40. The IA spectrum arising from self-trapped excitons, induced structural rearrangements by softening the glass network that strikingly reveal two relaxation mechanisms which differ by one order of magnitude. The fast kinetics of electron-lattice interaction occurs within 1 ps, exhibits a weak dependence on rigidity and dominates in the sub-bandgap region. In a stark contrast, the slow kinetics are associated with the structural changes in the bandgap region and depends strongly on network rigidity. Our results further demonstrate that amplitude of IA scales a linear relationship with excitation fluence which provides a unique way to induce structural rearrangements in over-coordinated network to exploit it for practical purposes. Our results modify the conventional concept of rigidity dependence of light-induced effects in network glasses, when excited with an ultrafast laser.

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Nanosecond light-induced transient absorption in As2S3: Self-trapped exciton recombination in amorphous chalcogenides

Cited by 10 publications

References 29 publications

Near resonant nanosecond laser-driven nonlinear optical response in As₅₀S₅₀ thin films

Near resonant nanosecond laser-driven nonlinear optical response in As₅₀S₅₀ thin films

Lightinduced Effects in Amorphous Chalcogenide Glasses: Femtoseconds to Seconds

Ultrafast light-induced softening of chalcogenide thin films above the rigidity percolation transition

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Nanosecond light-induced transient absorption in As2S3: Self-trapped exciton recombination in amorphous chalcogenides

Cited by 10 publications

References 29 publications

Near resonant nanosecond laser-driven nonlinear optical response in As50S50 thin films

Near resonant nanosecond laser-driven nonlinear optical response in As50S50 thin films

Lightinduced Effects in Amorphous Chalcogenide Glasses: Femtoseconds to Seconds

Ultrafast light-induced softening of chalcogenide thin films above the rigidity percolation transition

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Product

Resources

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Near resonant nanosecond laser-driven nonlinear optical response in As₅₀S₅₀ thin films

Near resonant nanosecond laser-driven nonlinear optical response in As₅₀S₅₀ thin films