Nonlinear Optical Transmission of Surface-Modified Nickel Sulfide Nanoparticles: Saturation of Absorption and Optical Limiting

Abstract

Saturable absorbers and optical limiters have contrary optical transmission properties. We report observations of simultaneous occurrence of both these effects in a nickel sulfide nanoparticle (average diameter ~5 nm) solution and a simultaneous quantitative measurement of both. Intensity-dependent nonlinear transmission studies carried out using a 7 ns Nd : YAG laser at 532 nm by the Z-scan method, revealed efficient optical limiting in nickel sulfide nanoparticle suspensions. Induced nonlinear optical scattering was identified to be the mechanism of optical limiting, and absorption at 532 nm was found to saturate. A modification of the conventional Z-scan implementation led to the retrieval of the saturation intensity, which is otherwise overshadowed by very strong nonlinear scattering.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation

“…Continuing, other metals nanoparticles such as those of nickel, antimony, or yttrium have also been reported for their NLO properties. While Sb 2 Se 3 nanoparticles presented a TPA coefficient of 5 × 10 –10 m/W at 532 nm, at the same wavelength NiS NPs displayed a very effective limiting threshold of 0.3 J/cm 2 originating from induced nonlinear scattering . Yttrium iron garnet (Y 3 Fe 5 O 12 ) nanoparticles, on their turn, showed strong RSA for 10 Hz and 7 ns laser pulses at 532 nm and OL intensity threshold of 103 MW/cm 2 at input laser pulse intensity of 152 MW/cm 2 …”

The Effects of Initial Laser Intensity on the Nonlinear Optical Properties of The Laser Dye DQOCI Doped Films Using Z-Scan Technique

“…For I 0 =3.03 kWatt/cm 2 (f=15 cm) and I 0 = 6.83 KWatt/cm 2 (f=10 cm), Z-scan curves show an upward peak, indicating a saturation of absorption (SA) that is known as the negative type of nonlinearity where the transmittance increased as the intensity increased (i.e. the absorbance decreased) [20]. When I 0 is 27.304 KWatt/cm 2 with a lens of a focal length of f=5 cm, the nonlinear absorption changes from SA to RSA or TPA, where the transmittances is reduced with the increase of intensity and the decrease of the focal length (Figure -6).…”

“…Self-lensing is a nonlinear optical phenomenon induced in the materials when it is exposed to an intense electromagnetic radiation, where the medium refractive index changes with the electric field intensity and, hence, it acts as a focusing lens [16,17] .A negative self-lensing (self-defocusing) before the focus reduces the diffraction, leading to a small beam at the aperture and a raise of the transmittance. When the sample crosses the focal plane to the right (+ z), the same self-defocusing effect will tend to raise the diffraction and minimize the aperture transmittance, as demonstrated in Figure -4 [20]. The change in intensity causes two photon absorption (TPA), multi-photon absorption, or saturation absorption (SA) in the sample as it travels through the beam waist.…”

“…Most of the molecules occupied the excited state. As the ground state is bleached, the system becomes increasingly transparent to the incident laser at 532 nm, resulting in a saturation of absorption [20]. This implies that the electrons on the valence band are transited to the conduction band and the laser intensity depletes many electrons from the valence band to the conduction band, leading to decreased absorbance [21].…”

Wetland Mapping of Sundar Ban Delta Using Automatic Feature Extraction

“…For example, the Red (0.63μmto0.69μm) and near infrared (NIR, 0.76μmto0.90μm) bands are mostly used to calculate the Normalized Difference Vegetation Index (NDVI) (Tucker1979) for monitoring the growth condition of Wetland plants. Moreover, the short-wave infrared (SWIR, 1.55μmto1.75μm) band is highly sensitive to soil/leaf water content [14], [15] and is used together with NIR in the formula of the Land Surface Water Index (LSWI). Note that LSWI is the negative of the Normalized Difference Built-up Index [16].…”