Effect of ZnO-HfO_2 hybrid nanocrystals on amplified spontaneous emission in Eu-doped ternary glass-ceramic waveguides

摘要

We discuss the fabrication of 1 mol7r Eu-doped 70 SiO_2-(30-x) HfO_1-x ZnO (x = 0, 2, 5 and 7 mol%) ternary glass-ceramic waveguides, and the effect of ZnO-HfO_2 hybrid nanocrystals on the optical gain in Eu-doped ternary waveguides. Formation and growth of ZnO-HfO_2 hybrid nanocrystals have been observed in the TEM images with increase of ZnO concentration in the samples. Waveguiding properties of Eu-doped ternary waveguides were measured using lab-built prism-coupling technique. Propagation losses of the waveguides were measured using photometric detection technique and found to be between (0.3 to 0.6)±0.2 dB/cm. We have further investigated the optical amplification of red emission line (~5D_0 → 7F_2) of Eu-ions in these waveguides using the variable stripe length method wherein the waveguides were pumped by continuous wave 532 nm laser in a stripe-like geometry using cylindrical lens The optical gain coefficients are found to be 5.3, 4.8, 3.7 and 0.1 cm"1 for ZnO concentration of 0, 2, 5 and 7 mo1% respectively.