Growth, Characterization, and Efficient Continuous-Wave Laser Operation in Nd,Gd:CaF2 Single-Crystal Fibers

Nd,Gd:CaF2 single-crystal fibers (SCFs) of various Nd3+ and Gd3+ concentrations were grown by a modified temperature gradient technique (TGT) using a home-designed multi-microchannel crucible. Powder and Laue X-ray diffraction measurements indicated the SCFs consist of pure monocrystalline CaF2 phase. Distributions of rare earth dopants in SCFs are proven to be uniform by both EDS and spectroscopic measurements. Laser diode (LD) pumped continuous-wave (CW) laser output at ∼1.06 μm spectral region of a highest slope efficiency of 42% and a maximum output power of 1.49 W were achieved. Comparison of laser performances between Nd,Gd:CaF2 SCFs and bulk crystal was analyzed, indicating the potential of fluoride SCFs in high-power laser applications.