Characterization of upconversion phenomena in Er3+-doped Ti:LiNbO3 waveguides using the fluorescence around 550 nm

In this paper, we report theoretical and experimental results concerning the upconversion phenomena around 550 nm in Er 3+ -doped Ti:LiNbO 3 waveguides. This phenomena corresponds transitions between the levels 4 S 3/2 implied by 4 I 15/2 . The waveguide is pumped near 980 nm with a laser diode. Two pump photons are used to bring the Er ions to the short lifetime level 4 F 7/2 . After a non-radiative transition to the level 4 S 3/2 , Er ions emit photons at 550 nm while falling down to the 4 I 15/2 level. By using the theoretical model elaborated by McCumber we evaluate the homogeneous emission cross sections and we obtain the following maximum values of the cross sections (sigma) H e (551.9 nm) equals 57.7 x 10 -26 m 2 for TE and (sigma) H e (558.1 nm) equals 52.5 x 10 -26 m 2 for TM polarizations. By measuring the fluorescence radiation around (lambda) equals 550 nm, we determine the rising and falling times and we obtain C equals 0.198 x 10 -23 m 3 /s as the value of the modulus of the homogeneous upconversion factor the value. The results presented here can be used in the design of integrated optoelectronic circuits and in the modeling of the laser action and optical amplification in Er 3+ -doped Ti:LiNbO 3 waveguides when a 980 nm pumping is considered.