All-fiber cyan laser at 491.5 nm

We report, for the first time to our knowledge, a compact continuous-wave all-fiber cyan laser. The all-fiber cavity consists of a 443-nm fiber-pigtail laser diode as pump source, a 4.5-cm single-clad Pr³⁺-doped fluoride fiber, and two custom-built dielectric-coated fiber-pigtail mirrors in the visible spectral region. Downconversion cyan lasing at 491.5 nm is directly achieved, providing a maximum output power of 97.5 mW with a slope efficiency of 23.7% and a power fluctuation of less than 0.41%. Such a compact all-fiber cyan laser may be of great significance to expand the color reproduction range of laser displays, and has potential applications in fluorescence imaging, underwater communication, and detection.