  We demonstrate a narrow line, fiber loop laser using Erbium-doped fiber as
the gain material, stabilized by using a microsphere as a transmissive
frequency selective element. Stable lasing with a linewidth of 170 kHz is
observed, limited by the experimental spectral resolution. A linear increase in
output power and a red-shift of the lasing mode were also observed with
increasing pump power. Its potential application is also discussed.
