Intensity-dependent two-photon absorption and its saturation in 2-methyl 4-nitroaniline nanofibers
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Intensity-dependent two-photon absorption and its saturation in 2-methyl 4-nitroaniline nanofibers C. Yogeswari1, K. M. Hijas1, M. Abith2, T. C. Sabari Girisun2, and R. Nagalakshmi1,*
1
Intermetallics and Nonlinear Optics Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli 620015, India 2 Nanophotonics Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620024, India
Received: 12 September 2020
ABSTRACT
Accepted: 28 October 2020
The Nonlinear absorption and its optical limiting properties of 2-methyl 4-nitroaniline-polymethylmethacrylate (2M4NA-PMMA) electro-spun nanofibers are investigated by Z-scan technique using Q switched Nd:YAG laser as an excitation source (532 nm, 5 ns, 10 Hz). Open-aperture measurements show that 2M4NA-PMMA nanofibers exhibit reverse saturable absorption. Intensity-dependent two-photon absorption coefficient demonstrates the presence of sequential two-photon absorption process involving real resonant intermediate states. The incorporation and orientation of 2M4NA in PMMA nanofibers are analyzed by XRD and it is found to range from 38 nm to 43 nm of crystallite size. SEM images illustrate the formation of smooth fibers using electrospinning by applying different voltages (12, 14, 17 kV). Ground-state absorption analysis shows that the nanofibers possess maximum absorption around 400 nm with a optical transmittance window (410–1200 nm) in the wide range of entire visible and NIR region. Lower optical limiting threshold (0.97 to 1.79 9 1012 W/m2) of 2M4NA-PMMA nanofibers ensures the suitability of optical fibers as optical limiters towards the development of laser goggles for pulsed green laser.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction The growth of interest in using the optical devices such as ultrafast optical modulator, switches, and limiters with intense laser sources has become more prominent in the last few years. In recent times, these electronic devices are replaced with high-power laser-driven optical counterpart as the latter provides an impressive outcome in processing, transport, and
data storage. Thus, it imposes the need for protecting photosensitive devices or sensor systems like human eyes from high-intense laser sources [1–3]. Optical devices can be protected by adopting the optical limiting (OL) mechanism during nonlinear interaction of light with matter through different nonlinear optical phenomena [4, 5]. The OL action could be achieved by nonlinearity in refraction, scattering, and absorption by which, nonlinear absorption of
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https://doi.org/10.1007/s10854-020-04786-6
J Mater Sci: Mater Electron
material is highly responsible for OL mechanism. There are various factors of nonlinear absorption which may occur due to two-photon (2PA) or multiphoton absorption, excited-state absorption, and free carrier absorption or with combination of these processes. Among them, 2PA is the most frequentl
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