[Photoluminescence spectra of trivalent neodymium doped TiBa glass microspheres].

In this work, TiBa glass microspheres doped with Nd3+ for morphology-dependent resonances of emission were designed and prepared. The emission spectra of TiBa glass plate and TiBa glass microspheres (45 and 13 microm in diameter) under 514 nm excitation were measured. The authors observed many regularly spaced, sharp peaks in the emission spectra of a Nd3+-doped glass microsphere. Based on the Mie scattering theory, the wavelength separation between the adjacent resonant peaks for the 45 microm sphere was calculated to be 3.0 for 810 nm. This value agrees well with the observed peak separation (3.1 nm), which indicates the contribution of the whispering gallery modes. The emission intensities of a Nd3+-doped TiBa glass microsphere (13 microm in diameter) in the 901.69 nm region were plotted against the excitation laser power. The emission intensities of the microsphere exhibit the linear dependence at the low excitation power (<2 mW). The 901.69 nm emission intensity of the microsphere steeply increases at the excitation power of 2 mW, which can be ascribed to the laser operation.