• Neelam Rani
• Karan Singh Gill
• Atul Jain

Presently, inorganic and organic materials are being replaced by semi-organics. They share the properties of both organic and inorganic. Many optically active amino acids with inorganic acids are promising materials for high efficient optical second harmonic generation, good thermal and mechanical strength and these are considered as the crucial factors for device fabrication, as they tend to combine the advantages of the organic amino acid with that of the inorganic acid [1]. L-lysine monohydrochloride (L-LMHCl), existing in monohydrate and dihydrate crystalline forms, is a widely investigated semi-organic nonlinear optical (NLO) material due to its chiral molecular structure, non-centrosymmetric crystal symmetry and multifunctional optical properties. Numerous experimental studies have systematically reported on its crystal growth, dopant-induced modifications, crystalline perfection, nonlinear optical efficiency, dielectric behavior, defect chemistry, hygroscopic nature and environmental stability. This review exclusively compiles experimentally reported results, including growth and characterization of pure and doped L-LMHCl crystals, polymer-coated hygroscopic crystals, defect and dielectric studies, EPR/ENDOR/DFT investigations, and electro- and elasto-optic behavior. Special emphasis is placed on moisture sensitivity and its control using polymethyl methacrylate (PMMA) coating. The review provides a consolidated, data-driven understanding of L-LMHCl crystals for nonlinear optical and photonic applications

Semioragnic, Non linear optical material, Hygroscopic, Crystal, Dielectric

"A REVIEW ON L-LYSINE MONOHYDROCHLORIDE DIHYDRATE SINGLE CRYSTALS AS SEMI-ORGANIC NONLINEAR OPTICAL MATERIALS", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.13, Issue 2, page no.b661-b671, February-2026, Available :http://www.jetir.org/papers/JETIR2602186.pdf

"A REVIEW ON L-LYSINE MONOHYDROCHLORIDE DIHYDRATE SINGLE CRYSTALS AS SEMI-ORGANIC NONLINEAR OPTICAL MATERIALS", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.13, Issue 2, page no. ppb661-b671, February-2026, Available at : http://www.jetir.org/papers/JETIR2602186.pdf