Fabrication of type-I and type-II SHG elements using organic 2-aminopyridinium 4-nitrophenolate 4-nitrophenol (2AP4N) single crystals grown by point seed rotation and novel RSR technique

The organic nonlinear optical (NLO)2-aminopyridinium 4-nitrophenolate 4-nitrophenol (2AP4N) single crystals were successfully grown by point seed rotation technique and novel Rotational Sankaranarayanan-Ramasamy (RSR) method. The unit cell parameters of the 2AP4Nsingle crystals were confirmed by single crystal X-ray diffraction (SXRD) analysis. The crystalline phase purity anddirection of RSR method grown crystal were confirmed by powder XRD (PXRD) measurement. The optical qualityof the 2AP4N crystal wasanalyzed by UV-Vis NIR spectrum analysis. TheKurtz–Perry powder technique was used to find the second harmonic generation (SHG) efficiency of the 2AP4N crystal using Nd:YAGlaser at the wavelength of 1064 nm. The SHG efficiency was found to be 4.5 times that of KDP. Refractive index measurement was carried out with different wavelength using prism coupling method. The phase matching angle of 2AP4N was find out by fitting Sellmeier equation. Based on the phase matching angle, the grown 2AP4N crystal wascut and the type-I and type-II SHG elements were fabricated.