Growth and optical properties of different compositions of LiNbO3 single crystal fibers

In this study the laser-heated pedestal growth (LHPG) method was used to grow lithium niobate (LiNbO3) single crystal fibers. The composition ratio were: [Li2CO3]/[Nb2O5] = 44:56, 45:55, 46:54, 47:53, 48:52, 48.6:51.4, 49:51 and 50:50 and were achieved by using different seed rods. The lattice parameters and crystalline structure of the crystals were determined by X-ray Single-Crystal Diffractometer (X-ray/CCD). The UV absorption spectra, Fourier-transform infrared spectrometer and Raman scattering spectroscopy results were used to find the optical properties and standard characterization of the different LiNbO3 single crystals. We note that the wavelength of the UV absorption edge was less when the Li2O composition was large. The plotted results, with the exception of the stoichiometric lithium niobate results, tended to fit a 2nd order polynomial curve. Transformation of the O–H absorption bands was observed. The Full-Width Half-Maximum (FWHM) of the Raman peak was found at 152 cm−1 in the E(TO) mode and decreased linearly as the amount of the Li2O composition increased. The Raman scattering results confirmed that the structure of the LiNbO3 crystals became more rigid when the amount of the Li2O composition increased.