We report the demonstration of continue wave operation of diode end-pumped Er:Y₂O₃ and Er:Lu₂O₃ ceramic lasers operating at 2.7 μm at room temperature. The maximum output power of 320 mW and 611 mW was obtained from the Er:Y₂O₃ and Er:Lu₂O₃ ceramic lasers, with slope efficiency of 6.5% and 7.6%, respectively. Characteristics of Red-shift in lasing wavelength of the ceramic lasers was investigated and discussed. The study indicates that under 967 nm and 976 nm LD pumping, 15 at.% Er-doped Lu₂O₃ ceramic exhibit a better performance than that of Y₂O₃ at room temperature.

We report on a highly efficient polycrystalline Tm:YAG ceramic laser in-band pumped by an Er:YAG laser at $1617\mathrm{nm}$. Lasing characteristics of 4.0 and $6.0\text{\hspace{0.17em} at.}\%$ ${\mathrm{Tm}}^{3+}$-doped YAG ceramics were investigated and compared. With an output coupler of 10% transmission, a maximum output power of $7.3\mathrm{W}$ was obtained at $2015\mathrm{nm}$ under $12.8\mathrm{W}$ of incident pump power, corresponding to a slope efficiency with respect to incident pump power of 62.3%.

Nonlinear amplifying-loop mirror (NALM) and nonlinear optical loop mirror (NOLM) are two basic Sagnac interferometers widely used in mode-locked fiber lasers. Here we construct a novel variant by replacing the amplifier in an NALM with an absorber, which forms a type of nonlinear absorbing-loop mirror (NAbLM). The optical waves counter-propagating within an ideal NAbLM possess equal optical powers when they return and interfere inside the used fiber coupler owing to the equal absorptions. Meanwhile, their nonlinear phase shifts can still differ if an asymmetric distribution of the absorber is employed. We theoretically predict that, in comparison to typical NALM and NOLM, the NAbLM can achieve relatively higher extinction ratio and larger modulation depth, resting on the unique equal-power interference. We then first used it as a saturable absorber in a holmium-doped fiber laser and achieved passively mode-locked operations in both normal and anomalous dispersion regimes. In the normal dispersion regime, h-shaped pulse was generated; whereas in the anomalous dispersion regime, both noise-like and dissipative-soliton-resonance-like pulses could be produced. NAbLM enables more options in nonlinear fiber optics especially when a high extinction ratio or large modulation depth is required.

We report on the high-power and high-efficiency operation of a polycrystalline Ho:YAG ceramic laser in-band pumped by a Tm fiber laser at $\sim 1907\mathrm{nm}$. Lasing characteristics of a $1.5\text{\hspace{0.17em} at.}\%$ and a $2.0\text{\hspace{0.17em} at.}\%$ ${\mathrm{Ho}}^{3+}$-doped YAG ceramic were investigated and compared. Using an output coupler of 6% transmission, over $21.4\mathrm{W}$ of cw output power at $2097\mathrm{nm}$ has been generated with the $1.5\text{\hspace{0.17em} at.}\%$ doped Ho:YAG ceramic under $35\mathrm{W}$ of incident pump power, corresponding to an average slope efficiency with respect to the incident pump power of 63.6% and an optical-to-optical conversion efficiency of 61.1%.

We report on a millijoule level Er:YAG ceramic pulsed vortex laser resonantly pumped by an annular beam at 1532 nm. By means of an uncoated YAG crystal plate inserting into the cavity and a proper thermal gradient on the ceramic, 1.03 mJ LG_0,-1 mode and 0.97 mJ LG_{0, + 1} mode were respectively produced, and no vortex mode instability problem was observed. We believe the directly generated millijoule level optical vortex with well–defined helicity will have potential applications in material modification and processing, high-field laser physics, and nonlinear optics, etc.