Abstract

We report a new frequency upconversion process based on energy transfer between Pr³⁺ ions grouped in pairs within a silicate fiber, despite the large non-radiative rates that characterize these fibers[1]. The pumping scheme requires a single wavelength in the near infrared (1.064 μm). Fluorescence in the blue (475 nm) and red (620 nm) are observed. It is also observed that stimulated emission from one of the intermediate level is present for strong pumping rates. As the pump source a Nd:YAG (ML or QSML) was used to excite the trivalent praseodymium ions, and both temporal and spectral measurements were performed. The Pr³⁺ doped libers used have a core diameter of ~6 μm, cut-off wavelength of ~ 900 run, and a Pr³⁺ concentration of ~ 300 ppm. figure 1 shows the emission spectra with the laser operating in the ML regime and an average coupled power of 800 mW dirough a 60 cm long fiber, corresponding to a peak power of 100 Watts.

© 1996 IEEE