Coupled-cavity erbium fiber lasers incorporating fiber grating reflectors

Narrow-linewidth erbium-doped fiber lasers of monolithic multiple linear cavity configurations that use intracore fiber grating reflectors are demonstrated. Robust single-frequency operation of a miniature coupled-cavity fiber laser with a linewidth of 30 kHz is reported. A novel multiple-cavity erbium fiber laser with simultaneous dual single-frequency lasing is also demonstrated. A 16-kHz linewidth and a frequency separation of 59 GHz with a stability of better than 3 MHz were achieved in this dual-frequency laser.