By using a new saturable absorber V 3+ :YAG, a flashlamp-pumped passively Q-switched Nd:GdVO 4 laser at 1.34 µm has been realized. Both a-cut and c-cut Nd:GdVO4 crystals are used. The output single-pulse energy and the pulse width versus the pump energy for different initial transmissions of V 3+ :YAG saturable absorbers are measured. The experimental results show that, c-cut Nd:GdVO4 laser can generate the shorter pulse width and higher energy in comparison to a-cut one.

In this paper, we demonstrate the efficient 1.3 um dual-wavelength operation of LD end-pumped Nd:YAG ceramic laser. With a plano-concave cavity, a maximum continuous-wave dual-wavelength output power of 5.92 W is obtained under an incident pump power of 20.5 W, giving a slope efficiency of 30.3% and an optical-optical conversion efficiency of 29.0%. With Co(2+):LaMgAl(11)O(19) crystal as the saturable absorber, the passively Q-switched dual-wavelength operation is achieved for the first time to our knowledge. The maximum passively Q-switched average output power is 226 mW, the minimum pulse width is 15 ns, and the highest pulse repetition rate is 133 kHz.

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A Ho:YAG ceramic microchip laser pumped by a Tm fiber laser at 1910 nm is passively Q-switched by single- and multi-layer graphene, single-walled carbon nanotubes (SWCNTs), and Cr²⁺:ZnSe saturable absorbers (SAs). Employing SWCNTs, this laser generated an average power of 810 mW at 2090 nm with a slope efficiency of 68% and continuous wave to Q-switching conversion efficiency of 70%. The shortest pulse duration was 85 ns at a repetition rate of 165 kHz, and the pulse energy reached 4.9 μJ. The laser performance and pulse stability were superior compared to graphene SAs even for a different number of graphene layers (n=1 to 4). A model for the description of the Ho:YAG laser Q-switched by carbon nanostructures is presented. This modeling allowed us to estimate the saturation intensity for multi-layered graphene and SWCNT SAs to be 1.2±0.2 and 7±1  MW/cm², respectively. When using Cr²⁺:ZnSe, the Ho:YAG microchip laser generated 11 ns/25 μJ pulses at a repetition rate of 14.8 kHz.

A passively Q-switched ytterbium doped fiber laser has been demonstrated with a Cr(4+):yttrium aluminum garnet saturable absorber and distributed stimulated Brillouin scattering. A linearly polarized output with approximately 375 kW peak power and a pulse duration as short as 490 ps have been obtained. A theoretical model is developed to simulate passive Q switching with the stimulated Brillouin scattering, which shows good agreement with the experiment.