A fiber laser is stabilized by introducing a calcium fluoride (CaF$_2$) whispering-gallery-mode resonator as a filtering element in a ring cavity. It is set up using a semiconductor optical amplifier as a gain medium. The resonator is critically …
We demonstrate a narrow-line fiber loop laser using erbium-doped fiber as 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 …