Multiphoton absorption in Er3+ doped fibres

We report the observation of green fluorescence from Er 3+ doped Ge silica optical fibre pumped by a CW titanium-sapphire laser in the 840-975 nm range. This emission is due to the multiphoton absorption and is attributed to the ( 2 H 11/2 + 4 S 3/2 ) decay level. The evolution of this emission as a function of the wavelength excitation and the effect of power pump are discussed