12.45 W wavelength-locked 878.6 nm laser diode in-band pumped multisegmented Nd:YVO₄ laser operating at 1342 nm

Ho:YAG laser at 2097 nm pumped by a narrow linewidth tunable 1.91 μm laser

This study presents a high efficiency Ho:YAG laser based on a narrow linewidth tunable 1.91 μm laser. A tunable Tm:YLF laser is the pump source and the wavelength continuous tunability ranges from 1906.04 to 1908.83 nm, corresponding to a linewidth of less than 0.41 nm. The tunable Tm:YLF laser is achieved by changing the operating temperature of the VBG. The output power of the Ho:YAG laser is between 21.04 and 23.53 W and the slope efficiency is between 64.08 and 68.26% at the pump power of 39.8 W. The output power and slope efficiency corresponding to the pump wavelength of 1907.36 nm are 23.53 W and 68.26%, respectively. This study illustrates that fine-tuning the pump wavelength is an effective way to improve the slope efficiency and output power of the Ho:YAG laser at room temperature.

11-watt single-frequency 1342-nm laser based on multi-segmented Nd:YVO4 crystal

High power continuous-wave (CW) single-frequency 1342 nm lasers are of interest for fundamental research, particularly, for laser cooling of lithium atoms. Using the popular Nd:YVO₄ laser crystal requires careful heat management, because strong thermal effects in the gain medium are the most severe limitations of output power. Here, we present a multi-segmented Nd:YVO₄ crystal design that consists of three segments with successive doping concentrations, optimized using a theoretical model. In order to quantify the optimization, we measured the thermal lens power of conventional crystal designs and compare them to our multi-segmented design. The optimized design displays a two times lower thermal lens dioptric power for the same amount of absorbed pump power in the non-lasing case. Using the optimized design, we demonstrate a high power all-solid-state laser emitting 10.0 W single-frequency radiation at 1342 nm when operating the laser crystal at room temperature. Further integration of the laser allows us to operate the laser crystal below room temperature for improving output power up to 11.4 W at 8°C. This is explained by the reduction of energy-transfer upconversion and excited-state absorption effects. Stable free-running operation at the low temperature of 8 °C is achieved with the power stability of ± 0.42 % by peak-to-peak fluctuation and frequency peak-to-peak fluctuation of ± 72 MHz in three hours.

Investigation on 1.3 μm laser performance with Nd:Gd0.69Y0.3TaO4 and Nd:Gd0.68Y0.3NbO4 mixed crystals

Laser performances around 1.3 μm are investigated in 879 nm laser diode (LD) end pumped Nd³⁺ doped mixed crystals with Nd:Gd_0.69Y_0.3TaO₄ and Nd:Gd_0.68Y_0.3NbO₄ crystals for the first time to our best knowledge. The maximum average power in LD end pumped Nd:Gd_0.69Y_0.3TaO₄ 1328 nm laser reaches 435 mW at 50 Hz with an optical-to-optical efficiency of 5.0% and a slope efficiency of 6.9%. In comparison, the highest average power of LD end pumped Nd:Gd_0.68Y_0.3NbO₄ laser at 1337 nm is 190 mW at 50 Hz, corresponding to an optical-to-optical efficiency of 3.5% and a slope efficiency of 4.2%.

Efficient 2122 nm Ho:YAG laser intra-cavity pumped by a narrowband-diode-pumped Tm:YAG laser

We first demonstrate an efficient Ho:YAG laser intra-cavity pumped by a narrowband-diode-pumped Tm:YAG laser. The pump wavelength of the laser diode was selected according to the excitation peak which is also one of the absorption peaks of a 3.5 at. % Tm:YAG crystal and was locked by volume Bragg gratings. In the Tm laser experiment, a maximum output power of 11.12 W, corresponding to a slope efficiency of 51.6%, was obtained. In the Ho laser experiment, a maximum output power of 8.03 W at 2122 nm with a slope efficiency of 38% was obtained for 24.96 W of diode pump power incident on the Tm:YAG rod.

5.2-W high-repetition-rate eye-safe laser at 1525 nm generated by Nd:YVO₄₋YVO₄stimulated Raman conversion

We report herein an efficient eye-safe Raman laser, which is based upon Nd:YVO₄₋YVO₄ and in-band pumped by a wavelength-locked laser diode array at 878.6 nm. By virtue of mitigated thermal load and improved pump absorption, a maximum average output power of 5.2 W at 1525 nm is obtained under the incident pump power of 30.6 W with the pulse repetition frequency of 140 kHz, corresponding to an optical efficiency of 17.0%.