Optical nonlinear properties of hydroxyapatite based materials

Pure hydroxyapatite (HAP) and biphasic HAP/β-TCP powders were synthesized using wet chemical route. Several heat treatment procedures (900–1300 °C) have been adopted in order to investigate their thermal stability and decomposition. The powder X-ray diffraction studies were carried out to examine the sample’s phase stability. The frequency of vibrations, surface morphology, structural stability, absorption and emission spectra were analyzed using Fourier Transform Infra Red (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Laser Raman analysis, UV-Vis and Fluorescence spectroscopy respectively. The nonlinear optical investigations were explored using Z-Scan (ZS) measurement for all the heat treated samples. The nonlinear (NL) absorption coefficient and nonlinear refractive index of the samples were evaluated using closed and open aperture Z-scan procedures. The observed pattern shows the negative nonlinear refractive index due to the peak followed by a valley. Further, the samples depict saturable absorption and it is also found that the saturable absorption varies as temperature increases. The influence of temperature in the optical nonlinearity of the samples was briefly discussed.