Single-frequency Ho(3+)-doped ZBLAN fiber laser at 1200 nm

A single-frequency (SF) fiber laser at 1200 nm was developed with a distributed Bragg reflector (DBR) configuration by splicing a 22 mm long highly holmium-doped ZBLAN (ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF) fiber with a pair of silica fiber Bragg gratings. The linewidth was estimated to be less than 100 kHz based on the measured frequency noise. The relative intensity noise was measured to be 19 dB. Our results highlight the exciting prospect that wavelength coverage of SF DBR fiber lasers can be expanded significantly by using rare-earth-doped ZBLAN fibers.