^aCentre for Research and Evaluation, Bharathiar University, Coimbatore, India bDepartment of Physics, The New College, Chennai, India

^cDepartment of Physics, S.A. Engineering College, Chennai, India

^dDepartment of Physics, Aalim Muhammed Salegh College of Engineering,

Chennai, India

^eDepartment of Physics, Adhi College of Engineering and Technology,

Kancheepuram, India

^fDepartment of Physics, VSA Engineering College, Uthamasolapuram, Salem,

India

The nonlinear optical material L-Tryptophanium phosphite (LTP) was synthesised and grown by the process of slow evaporation solution growth. Characterisations like single crystal XRD, FT-IR, and H1NMR spectral measurements were done to find the crystal structure and functional groups. The crystal was found to possess good transparency for the whole visible region from the UV-Vis-NIR spectral analysis. The thermal behaviour like stability and breakdown of the crystal were assessed using TG-DTA analyses. The hardness of the crystal was determined using Vickers micro hardness study. The Kurtz- Perry approach was used to study the nonlinear optical (NLO) characteristics of the crystal. A good value of conversion efficiency in second harmonic generation (SHG)

makes the generated crystal suitable for frequency conversion.