Passively Q-switched Nd:YVO(4) laser with a Cr(4+):YAG crystal saturable absorber

Quasi-2D Mn3Si2Te6 Nanosheet for Ultrafast Photonics

The magnetic nanomaterial Mn₃Si₂Te₆ is a promising option for spin-dependent electronic and magneto-optoelectronic devices. However, its application in nonlinear optics remains fanciful. Here, we demonstrate a pulsed Er-doped fiber laser (EDFL) based on a novel quasi-2D Mn₃Si₂Te₆ saturable absorber (SA) with low pump power at 1.5 μm. The high-quality Mn₃Si₂Te₆ crystals were synthesized by the self-flux method, and the ultrathin Mn₃Si₂Te₆ nanoflakes were prepared by a simple mechanical exfoliation procedure. To the best of our knowledge, this is the first time laser pulses have been generated using quasi-2D Mn₃Si₂Te₆. A stable pulsed laser at 1562 nm with a low threshold pump power of 60 mW was produced by integrating the Mn₃Si₂Te₆ SA into an EDFL cavity. The maximum power of the output pulse is 783 μW. The repetition rate can vary from 24.16 to 44.44 kHz, with corresponding pulse durations of 5.64 to 3.41 µs. Our results indicate that the quasi-2D Mn₃Si₂Te₆ is a promising material for application in ultrafast photonics.

Heterostructure ReS2/GaAs Saturable Absorber Passively Q-Switched Nd:YVO4 Laser

Heterostructure ReS₂/GaAs was fabricated on a 110-μm (111) GaAs wafer by chemical vapor deposition method. Passively Q-switched Nd:YVO₄ laser was demonstrated by employing heterostructure ReS₂/GaAs as a saturable absorber (SA). The shortest pulse width of 51.3 ns with a repetition rate of 452 kHz was obtained, corresponding to the pulse energy of 465 nJ and the peak power of 9.1 W. In comparison with the ReS₂ Q-switched laser and the GaAs Q-switched laser, the heterostructer ReS₂/GaAs Q-switched laser can generate shorter pulse duration and higher pulse energy.

Laser Q-switching with PtS2 microflakes saturable absorber

Numerous studies have been conducted to explore the performance of two-dimensional (2D) layered nano-materials based saturable absorber (SA) for pulsed laser applications. However, fabricating materials in nanoscale requires complicated preparation processes, high energy consumption, and high expertise. Hence, the study of pulsed laser performance based on the saturable absorber prepared by layered materials with bulk-micro size have gained a great attention. Platinum disulfide (PtS₂), which is newly developed group 10 2D layered materials, offers great potential for the laser photonic applications owing to its high carrier mobility, broadly tunable natural bandgap energy, and stability. In this work, the first passively Q-switched Erbium (Er) doped fiber laser is demonstrated with an operational wavelength of 1568.8 nm by using PtS₂ microflakes saturable absorber, fabricated by a simple liquid exfoliation in N-Methyl-2-pyrrolidone (NMP) and then incorporated into polyvinyl alcohol (PVA) polymer thin film. A stable Q-switched laser operation is achieved by using this PtS₂-SA within a fiber laser ring cavity. The maximum average output power is obtained as 1.1 mW, corresponding to the repetition rate of 24.6 kHz, the pulse duration of 4.2 μs, and single pulse energy of 45.6 nJ. These results open up new applications of this novel PtS₂ layered material.

Passive Q-switching with GaAs or Bi-doped GaAs saturable absorber in Tm:LuAG laser operating at 2μm wavelength

We report the first demonstration of a diode pumped passively Q-switched Tm:LuAG laser near 2μm wavelength with Bi-doped or undoped GaAs wafer as saturable absorber. For Bi-doped GaAs saturable absorber, stable Q-switched pulses with duration of 63.3ns under a repetition rate of 132.7 kHz and pulse energy of 5.51μJ are generated. In comparison to the passively Q-switched laser with undoped GaAs saturable absorber, the laser with Bi-doped GaAs can produce shorter pulses and higher peak power at almost the same incident pump power. The results suggest that Bi-doped GaAs can be an attractive candidate of saturable absorber for Q-switched laser near 2μm wavelength.

Single- and dual-pulse oscillation in a passively Q-switched Nd:YAG microchip laser

Experimental investigation of single and dual pulses in a passively Q-switched Nd:YAG microchip laser with a Cr4+:YAG saturable absorber has been reported. The dual pulses consist of a main and a satellite pulse with respective spectra, intensities, and durations. It is found that the preponderant oscillating mode gives birth to the main pulse, and the other oscillating mode corresponds to the satellite pulse. Our results demonstrate that the dual-pulse emission results from double-longitudinal-mode oscillation in high pump regime.

Passively Q-switched Yb3+:NaY(WO4)2 laser with GaAs saturable absorber

Passively Q-switched Yb(3+):NaY(WO(4))(2) lasers have been demonstrated using a GaAs saturable absorber. Under continuous wave pump mode, significant pulse shortening effects have been observed at high pump powers. At a pump power of 12 W, stable Q-switched output has been obtained with a pulse duration of 5 ns, pulse repetition rate of 83 kHz and a pulse to pulse timing jitter of less than 2%. With pulsed pump mode, much longer pulse duration and reduced pulse stability have been observed. It is proposed that the heating of GaAs may play an important role in the Q-switched operations under CW pump conditions.

Saturation Characteristics of Cr(4)+:YAG Crystals and Dye Films for Passive Q Switches

Measurements of the saturated transmission and the undepleted ground-state population density of both Cr(4+):YAG crystals and dye films as saturable absorbers have been experimentally attempted to understand the additional unsaturated losses in a high Q state. The saturated transmission of a saturable absorber is less than its maximum at a high saturation fluence because of the undepleted ground-state population density. Higher saturated transmission and lower undepleted ground-state population density have been observed for Cr(4+):YAG crystals than have been observed for dye films at high optical densities.

Passively Q-Switched Diode-Pumped Continuous-Wave Nd:YAG-Cr(4+):YAG Laser with High Peak Power and High Pulse Energy

A high peak power and high pulse energy passively Q-switched diode-pumped cw Nd:YAG laser at 1.064-mum wavelength has been demonstrated with Cr(4+):YAG crystal as the saturable absorber. The average output power of 7-12 W and pulse duration of 100-250 ns was obtained with kilohertz repetition rates. The highest peak power and pulse energy obtained were 30 kW and 3.4 mJ, respectively. All the output resulted from the TEM(00) mode with M(2) < 1.1. The thermal lensing effect of the saturable absorber was investigated, demonstrating that it played an important role in optimization of the output.

Laser-diode-pumped Cr(4)+, Nd(3)+:YAG with self-Q-switched laser output of 1.4 W

By use of a laser diode as a pump source, a self-Q-switched laser from a Cr, Nd:YAG crystal is demonstrated. The output Q-switched traces are very stable, the threshold pump power is 3.5 W, the pulse duration is 50 ns, and the slope efficiency is as high as 20%. In addition, the pulse width remains constant while the pulse repetition rate varies with pump power.