Gain characteristics of LaF3:Er, Yb nanoparticle-doped waveguide amplifier.

Fundamental rate equations and power propagation equations were used to simulate the gain factors of LaF3:Er, Yb nanoparticle-doped waveguide amplifiers excited at 980 nm. The gain first increased and then remained nearly constant with pump power increasing. The gain and the threshold pump power increased with increasing concentration of Er3+. The calculated gain of the concentration 0.75 x 10(26) ions/m3 on a 4 cm long waveguide was 3.6 dB. An optimum waveguide length was found for the highest gain and it was getting larger with the increase of the pump power. When the lifetime decreases from the Judd-Ofelt calculated value of 13.34 ms to the measured value of 60 micros, the required pump power of a 0.5 dB gain increased one level. We obtained a longer 4I(13/2) lifetime (100 micros) through decreasing the proportions of Er3+ and Yb3+ in nanoparticles and found that the threshold pump power decreased more at the expenses of saturated gain.