Mingqi Fan

Watt-level passively Q-switched Er:Lu₂O₃ laser at 2.84 μm using MoS₂.

Efficient diode-pumped passively Q-switched Er:Lu2O3 laser operation at 2.84 μm was realized. A few-layer MoS2 nanosheet film on a YAG substrate, was fabricated and employed as saturable absorber (SA) in a short plane-plane cavity. Under an absorbed diode laser pump power of 7.61 W, an average output power of 1.03 W was generated with a pulse duration of 335 ns and a repetition rate of 121 kHz, resulting in a pulse energy of 8.5 μJ.

Passively Q-switched Ho,Pr:LiLuF 4 laser with graphitic carbon nitride nanosheet film

A few-layer graphitic carbon nitride (g-CN) nanosheet film on an yttrium aluminum garnet substrate was fabricated and employed as saturable absorber for a passively Q-switched Ho,Pr:LiLuF4 laser at 2.95 μm. Under an absorbed pump power of 3.89 W at a pump wavelength of 1.15 μm, a maximum average output power of 101 mW was realized with a pulse duration of 420 ns and a repetition rate of 93 kHz. Even shorter pulse durations of 385 ns were obtained at a reduced output coupler transmission.

Experimental and theoretical investigation on passively Q-switched laser action in c-cut Nd:MgO:LiNbO₃.

The performance of a diode-pumped c-cut Nd:MgO:LiNbO3 laser at 1093 nm was demonstrated. Under an absorbed pump power of 7.450 W, a maximum continuous wave output power of 1.570 W was obtained, corresponding to a slope efficiency of 26.0%. For passive Q-switching operation, 24 ns pulses were observed with a repetition rate of 17.1 kHz, resulting in a peak power of 1357 W. The experimental results were theoretically analyzed by a rate equation model, in which the Gaussian spatial distribution of the intracavity photon density was taken into account.

Graphitic carbon nitride: A new saturable absorber for ∼3 μm

Graphitic carbon nitride (g-CN) based materials have been regarded as a novel class of multifunctional nanoplatforms for electronic, catalytic and energy applications. However, its optical characteristics have not received enough attention, yet. Although the theoretical bandgap of g-CN is quite large, which seriously limits the optical response range, various efficient strategies have been proposed to narrow the bandgap, such as heteroatom doping and defect control [1]. Surface sensitization, pore texture tailoring, heterojunction construction and co-catalyst loading have also been applied to promote the photoresponsivity of g-CN [1]. Furthermore, atomically thin g-CN nanosheets possess higher charge carrier density due to an obvious increase of density of states at the conduction band edge with respect to the bulk counterpart [2]. The saturable absorption response of g-CN has been demonstrated in the near infrared wavelength range [2, 3]. Here, we report on the fabrication of a g-CN saturable absorber (SA) and discuss its saturable absorption properties near 3 μm for the first time. By utilizing this home-made g-CN-SA, efficient Q-switched Er:Lu2O3 laser operation at 2.84 μm was realized, delivering a maximum average output power of 1.09 W and a pulse duration of 351 ns, which is among the shortest Q-switched pulses previously achieved with 2D-SAs in this wavelength range.