Yellow pumped Pr3+-doped ZBLAN fiber laser at 1015 nm.

To date, lasing in the visible to near-infrared wavelengths has been studied for praseodymium-doped fluoride fibers with the upper energy level of 3P0. In this Letter, a fiber laser operating at 1015 nm has been realized for the first time, to the best of our knowledge, which confirms a new mechanism where 1D2 can be the upper energy level. A maximum output power of 241 mW, with a slope efficiency of 30%, was achieved by using a 150-cm-long active fiber pumped at a maximum pump power of 823 mW. Furthermore, the broad emission spectra of Pr3+-doped fibers in the near-infrared band have been exploited as new, to the best of our knowledge, spectral sources.

Wavelength extension and power improvement of red Pr3+:YLF lasers.

High-power red lasers (mainly at 639 and 670 nm) based on Pr3+:YLF crystals have been presented in many works. However, the spectral resources of Pr3+:YLF in the red region have not been fully developed to obtain lasers due to their relatively low emission cross sections and the irrepressible strong emission at ∼639 nm. In this work, we propose a scheme to further develop the spectral resources of Pr3+:YLF in the red region and improve the red laser powers based on this crystal. The laser wavelengths are obtained from 634.5 to 674.7 nm (continuous tunings are achieved at some wavebands). To the best of our knowledge, the output powers obtained at 638.7, 644.6, 670.1, and 674.7 nm (2.88 W, 1.87 W, 3.55 W, and 1.73 W, respectively) are the highest to date. Furthermore, lasing originating from the 3P2 energy level of Pr3+:YLF (∼653 nm) is realized for the first time.

High-efficiency broadband tunable green laser operation of direct diode-pumped holmium-doped fiber.

Green laser sources have become increasingly important for the application in scientific research and industry. Although several laser approaches have been investigated, the development of green lasers with the necessary efficiency and spectral characteristics required for practical deployment continues to attract immense interest. In this study, the efficient green laser operation of a Ho3+-doped fluoride fiber directly pumped by a commercial blue laser diode (LD) is experimentally investigated at various active fiber lengths. In the free-running laser, the slope efficiency was optimized up to 59.3% with 543.9 nm lasing, with respect to the launched pump power, using a 20-cm long active fiber. This is the maximum slope efficiency reported to date for a green fiber laser. A maximum output power of 376 mW at 543.5 nm was achieved by using a 17-cm long active fiber pumped at a maximum available launched pump power of 996 mW. Moreover, broadband tuning operation was demonstrated by employing a range of active fiber lengths, together with an intracavity bandpass filter. The operating wavelength was tunable from 536.3 nm to 549.3 nm. A maximum tuning power achieved was 118 mW at 543.4 nm for a 17-cm long active fiber. Moderate Ho3+-doped fiber length is shown to be effective in producing a high performance of a green fiber laser. The short-length of the active fiber considerably extends the green short wavelength operation due to limited reabsorption of the signal below 540 nm.