Efficient and wavelength Ho:YO ceramic laser intra-cavity pumped by diode-pumped thulium laser.

A 2.1 µm Ho:YO ceramic laser with high cost-effectiveness and good spectral designability was constructed by using different thulium-doped materials as intra-cavity pump medium. When using 785 nm diode-pumped Tm:YAP as the pump source, the 2116 nm Ho:YO ceramic laser achieved 4.9 W output power with a slope efficiency of 39.7%, with the slope efficiency reached 70% of the free-running Tm:YAP laser at 1986 nm. When the Tm:YAG was used as pump source, the emission wavelength of Tm:YAG at 2012 nm overlapped with the short wavelength region in the absorption spectrum of Ho:YO, which can reduce the absorption loss of Ho:YO at short wavelengths and increase the gain cross-sections accordingly. Then what we believe to be novel emitting wavelengths of 2043 nm, 2061 nm, and 2073 nm were further achieved in addition to the expected wavelength of 2116 nm. To our knowledge, this is the first report on the laser operation of holmium-doped sesquioxides below 2100 nm. The excellent designability of thulium laser intra-cavity pumping scheme provides a new solution for the effective utilization of broadband fluorescence spectra for holmium-doped sesquioxides.