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Abstract
This is a comment on the previously published paper “Enhancement of nonlinear optical properties of BaTiO3 nanoparticles by the addition of silver seeds,” [Opt. Express 20, 26511 (2012) [CrossRef] ]. An erroneous equation given in the manuscript is corrected with a more accurate equation in this comment.
© 2017 Optical Society of America
An inaccurate equation given in a previously published paper by B Yust, et al. [1] is replaced with a more accurate equation here. Addressing the thermal nonlinearity in z-scan experiment during low power cw laser irradiation, the authors have mentioned two models, namely by Cuppo, et al. [2] and Falconieri [3] in their paper. In fact, both these papers were not the original papers to be cited. Moreover, in his paper, Falconieri has generalized the original aberrant thermal lens model for multiphoton absorption under high-repetition rate pulsed laser excitation. The original aberrant thermal lens model is developed by Sheldon et al. [4]. According to Yust et al. the position dependent transmitted intensity for closed aperture z-scan is given by
However, referring Eq. (35) of the original paper [4], in which the second order term of ΔΦ0 (given as θ in that paper) is neglected for small values of ΔΦ0, we can deduce the position dependent normalized intensity, including the second order term, as derived by Carter et al. [5]Here higher order ΔΦ0/4 term is neglected and ΔΦ0 is taken as negative, which is true for most of the liquids.The same equation can also be derived from [3] itself, which Yust et al. quoted in their paper, by setting q = 1, for single photon absorption for low power CW laser irradiation, in Eq. (10) of [3].
Experimental data measured using a 30mW continuous wave DPSS laser emitting at 532nm is focused using a plano-convex lens having 100mm focal length to a spot size of 53micrometer. Carbon black suspension in water, having an absorption coefficient of 0.033mm−1 at 532nm, is used as the sample and the closed aperture Z-scan measurement is performed using a photodiode-pinhole combination placed 2m away from the sample. Figure 1. shows the measured data and the theoretical fit using the two equations. It is very clear that Eq. (2) gives a better fit than Eq. (1) to the measured data.
References and links
1. B. G. Yust, N. Razavi, F. Pedraza, Z. Elliott, A. T. Tsin, and D. K. Sardar, “Enhancement of nonlinear optical properties of BaTiO3 nanoparticles by the addition of silver seeds,” Opt. Express 20(24), 26511–26520 (2012). [CrossRef] [PubMed]
2. F. L. S. Cuppo, A. M. F. Neto, and S. L. Gomez, “Thermal-lens model compared with the Sheik-Bahae formalism in interpreting z-scan experiments on lyotropic liquid crystals,” J. Opt. Soc. Am. B 19(6), 1342–1348 (2002). [CrossRef]
3. M. Falconieri, “Thermo-optical effects in z-scan measurements using high-repetition-rate lasers,” J. Opt. A, Pure Appl. Opt. 1(6), 662–667 (1999). [CrossRef]
4. S. J. Sheldon, L. V. Knight, and J. M. Thorne, “Laser-induced thermal lens effect: a new theoretical model,” Appl. Opt. 21(9), 1663–1669 (1982). [CrossRef] [PubMed]
5. C. A. Carter and J. M. Harris, “Comparison of models describing the thermal lens effect,” Appl. Opt. 23(3), 476–481 (1984). [CrossRef] [PubMed]
