Modeling of Yb/sup 3+/-sensitized Er/sup 3+/-doped silica waveguide amplifiers

A model for Yb/sup 3+/-sensitized Er/sup 3+/-doped silica waveguide amplifiers is described and numerically investigated in the small-signal regime. The amplified spontaneous emission in the ytterbium-band and the quenching process between excited erbium ions are included in the model. For pump wavelengths between 860 and 995 nm, the amplified spontaneous emission in the ytterbium-band is found to reduce both the gain and the optimum length of the amplifier significantly. The achievable gain of the Yb/sup 3+/-sensitized amplifier is found to be higher than in an Er/sup 3+/-doped silica waveguide without Yb/sup 3+/ (18 dB versus 9 dB for a pump power of 100 mW). However, it is important to optimize the Yb-concentration according to the choice of pump wavelength.>