Q-switched Laser Absorbing Material-Nano Tungsten Disulfide

Q-switched laser technology is a technology that compresses the general output continuous laser energy into a very narrow pulse to emit, so that the peak power of the light source can be increased by several orders of magnitude. Because Q-switched lasers can obtain high peak power and narrow pulse width, they are widely used in industrial processing and scientific research fields, such as the manufacture of ultrafine semiconductors, terahertz wave equipment and so on.

At present, Q-switched lasers have many wavelengths, including 266, 355, 523.5, 526.5, 532, 656.5, 660, 1047, 1053, 1064, 1313, 1319 nm. Laser head is one of the important components of Q-switched lasers. It is found that two-dimensional monolayer nano-tungsten disulfide can also be used in the manufacture of laser absorbers.

Because of the special structure of sandwich sandwich, the direct bandgap of tungsten disulfide monolayer can be changed from indirect to direct, and its direct bandgap is about 2.1eV. High energy pulsed laser can be obtained by tungsten disulfide Q-switched lock film, and nanosecond or even femtosecond pulsed laser output can be achieved. Furthermore, the number of layers and defects of tungsten disulfide materials can be controlled by optimizing the preparation process, and different energy band gaps can be obtained to realize the normal operation of saturable absorbers in different laser bands.

Some scholars have developed a new Q-switched pulse laser with single-layer nano-tungsten disulfide as absorption material. Its characteristics include: sequentially arranged semiconductor laser, coupling lens, plane mirror, Yb: GAB crystal, tungsten disulfide saturable absorber and concave lens.

Semiconductor lasers have tail fiber output. The continuous light generated by semiconductor lasers is focused by coupling lens. After focusing, the continuous light passes through plane mirror and Yb:GAB crystal in turn. Then it passes through tungsten disulfide saturable absorber. Finally, Q-switched laser is output by concave lens.

Compared with graphene and other transition metal sulfides, tungsten disulfide has a 2.1ev direct band gap and unique nonlinear saturation characteristics. Therefore, tungsten disulfide saturable absorber is used as Q-switching device. By changing the layers and defects of tungsten disulfide material on the substrate surface, different energy band gaps can be obtained to realize the operation of tungsten disulfide saturable absorber material in different laser bands. It is cheaper and easier to achieve pulse output. 

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