Third-Order Nonlinear Optical Effects in Nanostructured Materials: A Comparative Review of Bio-Tellurium, Graphene, and Carbon Nanotube Hybrids

Abstract

This review presents an overview of the third-order nonlinear optical (NLO) behavior of biologically synthesized tellurium (Bio-Te) nanocrystals, graphene, and carbon nanotube (CNT) hybrids, emphasizing the role of dimensionality, chemical functionalization, and dispersion medium in tuning optical behavior. The motivation lies in advancing materials for photonic applications such as optical limiting (OL), where nonlinear phenomena like reverse saturable absorption (RSA), saturable absorption (SA), and nonlinear scattering are essential to meeting the growing demand for high-performance optical limiters and photonic devices. The review first explores the synthesis of Bio-Te nanocrystals produced via anaerobic bacterial reduction and dispersion with poly(m-phenylenevinylene-co-2,5 Dioctoxy-p-phenylenevinylene) (PmPV) to improve solubility and photonic interaction. The discussion turns to investigate graphene, focusing on unoxidized graphene nanosheets synthesized via liquid-phase exfoliation (LPE) in γ-butyrolactone and stabilized using polymer nanocomposites such as PVK-functionalized reduced graphene oxide (RGO-PVK). Lastly, the review examines CNT-based nanohybrids composed of double-walled (DWNT), multi-walled (MWNT), and single-walled (SWNT) nanotubes, functionalized with fluorescein (FITC), rhodamine B (RITC), or fullerene C60, and dispersed in solvents such as DMF (dimethylformamide) and PmPV/Toluene. Characterization techniques such as UV-Vis, Raman spectroscopy, and open aperture Z-scan confirmed the presence of doping effects, π–π interactions, and enhanced NLO responses. These findings aim to guide future design of nonlinear optical materials for advanced applications in optical switching, photoprotection, and data modulation technologies.