Research Article Reverse Saturable Absorption in Substituted Hydrazones and Its Structure-Property Relationship for Photonic Applications Vijayakumar Sadasivan Nair, 1 Sharafudeen Kaniyarakkal , 2 Shiju Edappadikkunnummal, 3 Joicy John, 2 Sudheesh Palengara, 4 Siji Narendran, 5 and Suresh Thelakkadan Puthiyaveettil 6 1 PG and Research Department of Physics, N S S College Pandalam, Pathanamthitta 689501, Kerala, India 2 Department of Physics, Kuwait College of Science and Technology, Doha 35004, Al-Asimah, Kuwait 3 International School of Photonics, Cochin University of Science and Technology, Kochi 682022, Kerala, India 4 Department of Physics, N S S College Manjeri, Malappuram 676122, Kerala, India 5 Department of Physics, T K M M College Nangiarkulangara, Alappuzha 690513, Kerala, India 6 Department of Physics, Government Brennen College, alassery, Kannur 670106, Kerala, India Correspondence should be addressed to Sharafudeen Kaniyarakkal; s.valappil@kcst.edu.kw Received 23 October 2021; Revised 30 March 2022; Accepted 13 April 2022; Published 13 May 2022 Academic Editor: Vincenzo Palleschi Copyright © 2022 Vijayakumar Sadasivan Nair et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. e third-order nonlinear optical properties of three hydrazone derivatives, namely, ethyl 2-((2E)-2-(4-(dimethylamino)ben- zylidene]hydrazinyl)-5-nitrobenzoate, ethyl 2-((2E)-2-(4-chlorobenzylidene)hydrazino)-5-nitrobenzoate, and methyl 5-nitro-2- ((2E)-2-(4-nitrobenzylidene)hydrazino)benzoate were investigated by the single beam Z-scan technique with nanosecond laser pulses at 532 nm. e compounds were doped into PMMA (poly (methyl methacrylate)), and their third-order nonlinearity was studied with a prospective of reaching a compromise between processability and high nonlinear optical behavior. e optical limiting study of the samples was carried out at 532 nm. e measured values of the third-order nonlinear susceptibility, χ (3) , and the nonlinear refractive index, n 2 , are of the order of 10 − 13 esu and 10 − 11 esu, respectively. e nonlinear absorption in materials was attributed to reverse saturable absorption. e results are quite promising for possible applications in photonic devices. 1. Introduction e prospect of using organics as nonlinear optical materials for photonic switching and optical limiting applications has been the subject of many investigators during the past de- cade and has a great impact on information technology and industrial applications. In particular, the photonic appli- cations such as all-optical switching, three-dimensional optical devices, all-optical limiting, medical science, and other optical fields [1, 2]. Organic materials are most at- tractive owing to the known rich variety of organic com- pounds and the inherent flexibility in synthesizing such compounds with desired properties. e nonlinearity in these molecules has been found to originate from a strong delocalization of π-electrons along the length of the molecule [3, 4]. By molecular engineering, we can design organic systems for better nonlinear properties, and the study of the linear and nonlinear optical (NLO) coefficients helps us to identify such materials. e third-order nonlinearity of conjugated organic compounds can be enhanced by (i) increasing the conju- gation length, to increase the distance over which charge can be transferred; (ii) creating a donor-acceptor-donor motif by substitution, to increase the extent of charge transfer from the ends of the molecule to the center; and (iii) reversing the sense of symmetric charge transfer by substituting electron acceptors and donors, thereby cre- ating acceptor-donor-acceptor compounds. e above strategy was used in the synthesis of the hydrazone de- rivatives, which are studied in this report, with a goal to Hindawi Laser and Particle Beams Volume 2022, Article ID 3382780, 8 pages https://doi.org/10.1155/2022/3382780