Few-layer MoS2/PMMA composite solid bulks with remarkable optical limiting properties in both femtosecond and picosecond domains have been successfully demonstrated.

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A technique for modifying the saturable absorption (SA) properties of 2D nanofilms and a pulse width-dependent theoretical model of SA considering interband exciton recombination have been successfully demonstrated.

In this work, we successfully fabricated a transmissive saturable absorber (SA) with Ti2CTx MXene using the spin-coating method. By inserting the Ti2CTx saturable absorber into the diode-pumped solid-state (DPSS) Nd:YAG laser, a stable passively Q-switched operation was obtained near 1.06 μm. At a pump power of 4.5 W, we obtained the shortest pulse duration of 163 ns with a repetition rate of 260 kHz. The corresponding single pulse energy and peak pulse power were 3.638 μJ and 22.3 W, respectively. The slope efficiency and the optical conversion efficiency of the laser were 21% and 25.5%, respectively. To the best of our knowledge, this is the first time that Ti2CTx was used in the passively Q-switched solid-state lasers. This work demonstrates that Ti2CTx can be a promising saturable absorber for solid-state laser pulse generation.

For the first time, to the best of our knowledge, analytical expressions for mutually compensating the curved mirror astigmatism in the two terminal arms of a folded resonator are deduced and experimentally verified. The analytical expressions are derived using the theory of the propagation and transformation of Gaussian beams under few assumptions. Our exact analytical expressions describe the necessary and sufficient conditions for simultaneously compensating astigmatism in two arms of a sequence of two off-axis curved mirrors. The theoretical results indicate that, when the astigmatism compensation expressions are satisfied, the astigmatism introduced by a folded curved mirror can be mutually compensated by another folded curved mirror, even if there is no additional Brewster element inside the cavity. The astigmatism can only be successfully eliminated by using a pair of concave mirrors or convex mirrors. Our analytical expressions can be used to design astigmatically compensated folded resonators without a Brewster element. A typical side-pumped z-shaped cavity Nd:YAG laser is employed to demonstrate the astigmatic compensation. Experimental measurements of the pattern of the laser output beam show that not only the spot intensity profile deformation but, in addition, the phase distortion in the two terminal arms can be simultaneously compensated completely in the cavity, which is in good agreement with the analytical predictions.