60.4 W continuous-wave single-frequency laser output from a two-stage Nd:YAG single-crystal fiber amplifier.

A Nd:YAG single-crystal fiber amplifier for the amplification of continuous-wave single-frequency laser end-pumped by a laser diode (LD) is investigated. With a two-stage amplification configuration, an output power of 60.4 W under the total incident pump power of 200 W is achieved, which is, to our knowledge, the highest power from a continuous-wave single-frequency laser achieved with a single-crystal fiber scheme. The extraction efficiency reaches 41.6% in the second amplification stage, which is comparable with Innoslab amplifiers. The beam quality factors M2 at the maximum output power in the horizontal and vertical direction are measured to be 1.51 and 1.38, respectively. The long-term power instability for 1 hour is 0.97%.

Watt-level passively mode-locked Tm:YLF laser at 1.83 µm.

Passive, continuous-wave mode-locked (CWML) operation of a 1.83 µm Tm:YLF laser is experimentally demonstrated for the first time, to the best of our knowledge. Two specially selected output couplers are used to realize this operation. Stability of the CWML laser is obtained with a commercial semiconductor saturable absorber mirror. The maximum average output power is 1.04 W with a pulse duration of 107 ps and repetition rate of 54.1 MHz. Further, a 0.1 mm fused-quartz Fabry-Perot etalon is used to tune the central wavelength of the stable CWML laser at 1827.2 nm, 1829.5 nm, 1831.9 nm, and 1833.5 nm.

High-power and high-efficiency short wavelength operation of a Tm:YLF laser at 1.83 µm.

A high-power and high-efficiency diode-end-pumped Tm:YLF laser at 1.83 µm is demonstrated for the first time, to our best knowledge. To make the laser operate at 1.83 µm, a simple way of controlling the transmittance of the output coupler is used, and the criteria of the transmittance of the output coupler at the emission peaks of Tm:YLF are theoretically analyzed, which are verified by experimental results. Based on the theoretical analysis, laser oscillation at only 1.83 µm is realized. Maximum output power at 1833 nm is 8.5 W with corresponding slope efficiency of 53.4% regarding absorbed pump power. In addition, tunability of this laser from 1827 nm to 1837 nm is obtained. Laser beam quality at 1833 nm is measured to be 1.4 at maximum output power. The achieved laser performance represents considerable improvement compared to any other bulk laser emitting around 1.83 µm.