Ti2CTx MXene as a Saturable Absorber for Passively Q-Switched Solid-State Lasers

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.

Study on Femtosecond Laser Processing Characteristics of Nano-Crystalline CVD Diamond Coating

Ultra-short pulse laser interaction with diamond materials has attracted extensive interest in micro- and nano-machining, especially for the fabrication of micro tools, because of the straightforward method and high precision. Thanks to the development of chemical vapor deposition (CVD) technology, high-quality CVD diamonds are employed in more varieties of tools as performance-enhancing coatings. The purpose of the experiments reported here was to explore the machinability of CVD diamond coating under the irradiation of femtosecond (fs) pulsed laser. The factor-control approach was adopted to investigate the influence of scanning speed, single pulse energy and repetition rate on the surface quality and carbon phase transition of CVD diamond coating. The material removal rate and surface roughness were evaluated. The interaction mechanism of scanning speed, single pulse energy, and repetition rate were discussed, and the fs laser ablation threshold of CVD diamond coating was calculated. It was demonstrated that two ablation mechanisms (weak and intensive) were in existence as evidenced by the distinct surface morphologies induced under different processing conditions. A strong dependence on the variation of scanning speed and pulse energy is identified in the examination of surface roughness and removal rate. Lorentzian–Gaussian deconvolution of Raman spectra illustrates that fs laser irradiation yields a strong modification effect on the coating and release the compressive stress in it. Furthermore, a newly defined parameter referring to the fs laser energies applied to unit volume was introduced to depict the degree of ablation and the Taguchi method was used to figure out the significance of different parameters. The ablation threshold of CVD diamond coating at the effective pulses of 90 is calculated to be 0.138 J/cm2.

Nanosecond level passively Q-switched Nd:YAG and Nd:YVO4 laser using black phosphorus as a saturable absorber

Black phosphorus (BP) saturable absorber (SA) solution is fabricated by liquid-phase exfoliation method. By using the BP-SA solution, a compact diode-pumped passively [Formula: see text]-switched Nd:YAG and [Formula: see text] laser has been demonstrated. 100 Hz and 1 kHz repetition rate pulse lasers are achieved, respectively. The minimum pulse duration is 3.56 ns. In the [Formula: see text]-switched [Formula: see text] laser with wideband absorbers, the lowest repetition rate and the shortest pulse duration are obtained for the first time to the best of our knowledge. The maximum single pulse energy is as much as 0.1 mJ. Our results show that BP-SA solution can be developed as an effective SA to achieve nanosecond pulse laser.

Passive Q-Switching with Graphene Saturable Absorber in Nd:YAG Operating at 1064nm

A graphene-PVA film is fabricated by using polyvinyl alcohol(PVA), which provides excellent mechanical property and easy operation. Based on the numerous advantages of graphene in optical and mechanical characteristics,Graphene was used as absorber with passively Q-switched Nd:YAG solid laser in our experiment. Furthermore, there are no changes in the structure and characteristics of graphene. Inserting our graphene-PVA SA mirror to the Nd: YAG laser, we ultimately get that the single pulse energy is about 7.68μJ, and that the shortest pulse width is about 640ns. The experiment results prove that our graphene-PVA SA mirror is feasible and suitable for Q-switched lasers.