Room-temperature upconversion fiber laser tunable in the red, orange, green, and blue spectral regions

We report continuous-wave tunable laser operation over the 635–637-, 605–622-, 517–540-, and 491– 493-nm wavelength bands in Pr3+/Yb3+-doped ZrF4 –BaF2 –LaF3 –AlF3 –NaF (ZBLAN) optical fiber. A single Ti:sapphire laser is used as the pump source. With as little as 60 mW of pump power launched into the fiber, laser output is obtained over the entire pump-wavelength tuning range of 780 to 880 nm. At a pump wavelength of 860 nm, we have produced output powers of 300 mW at 635 nm (760 mW of launched pump power), 45 mW at 615 nm (430 mW of launched power), 20 mW at 520 nm (200 mW of launched power), and 4 mW at 493 nm (200 mW of launched power).