Fabrication and characterization of optical planar waveguides activated by erbium ions for 1.5 μm applications

摘要

Recent results obtained for SiO_2 - HfO_2: Er~(3+) and SiO_2 - TiO_2: Er~(3+) - Yb~(3+) waveguides are presented. (100-x)SiO_2 -xHfO_2 (x = 10, 20, 30, 40 mol) planar waveguides, doped with 0.01 and 0.3 mol % Er~(3+) ions were prepared by sol-gel route, using dip-coating deposition on v-SiO_2 substrates. The waveguides were characterized by m-line, Raman and photoluminescence spectroscopy. The spectral shape of the band assigned to the ~4I_(13/2) → ~4I_(15/2) transition does not change practically with the hafnium and erbium content. The ~4I_(13/2) level decay curves present a single-exponential profile, with a lifetime between 5.5 and 7.1 ms, for the 0.3 mol% doped samples, and between 8.5 and 6.6 ms for the 0.01 mol% doped samples. The SiO_2 - TiO_2: Er~(3+) - Yb~(3+) waveguides were prepared by rf-sputtering technique. All waveguides were single-mode at 1550 nm. The losses, for the TE_0 mode, were evaluated at 632.8 and 1300 nm and an attenuation coefficient equal or lower than 0.2 dB/cm was measured both at 632.8 nm and 1300 nm. The emission of ~4I_(13/2) → ~4I_(15/2) of Er~(3+) ion transition was observed upon excitation in the TE_0 mode at 981 and 514.5 nm. Back energy transfer from Er~(3+) to Yb~(3+) was demonstrated by measurement of Yb~(3+) emission upon Er~(3+) excitation at 514.5 nm. Photoluminescence excitation spectroscopy was used to obtain information about the effective excitation efficiency of Er~(3+) ions by co-doping with Yb~(3+) ions.