S -band Tm3+-doped tellurite glass microsphere laser via a cascade process

We present a Tm3+-doped tellurite glass microsphere laser operating in the S band via a cascade process. The microsphere is fabricated by melting the end of a tellurite glass wire, and the microsphere laser is pumped at 800nm using a tapered optical fiber. Laser oscillation is observed simultaneously in the S band and the 1.9μm band. The threshold of lasing in the 1.9μm band is lower than in the S band, and the quantum efficiency in the 1.9μm band increases with pump power above the lasing threshold of the S band.