Fabrication and characterization of optical planar waveguides activated by erbium ions for 1.5-¼m applications.

Recent results obtained for SiO2 - HfO2: Er 3+ and SiO2 - TiO2: Er3+ - Yb 3+ waveguides are presented. (100-x)SiO2 - xHfO 2 (x = 10, 20, 30, 40 mol) planar waveguides, doped with 0.01 and 0. 3 mol % Er3+ ions were prepared by sol-gel route, using dip-coating deposition on v-SiO2 substrates. The waveguides were characterized by m-line, Raman and photoluminescence spectroscopy. The spectral shape of the band assigned to the 4I13/2 -> 4I 15/2 transition does not change practically with the hafnium and erbium content. The 4I13/2 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 SiO2 - TiO2: Er3+ - Yb3+ waveguides were prepared by rf-sputtering technique. All waveguides were single-mode at 1550 nm. The losses, for the TE0 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 4I13/2 -> 4I15/2 of Er 3+ ion transition was observed upon excitation in the TE0 mode at 981 and 514.5 nm. Back energy transfer from Er3+ to Yb 3+ was demonstrated by measurement of Yb3+ emission upon Er3+ excitation at 514.5 nm. Photoluminescence excitation spectroscopy was used to obtain information about the effective excitation efficiency of Er3+ ions by codoping with Yb3+ ions.