Nonlinear Saturable Absorption Properties Research Articles

WS2 mode-locked ultrafast fiber laser.

Graphene-like two dimensional materials, such as WS2 and MoS2, are highly anisotropic layered compounds that have attracted growing interest from basic research to practical applications. Similar with MoS2, few-layer WS2 has remarkable physical properties. Here, we demonstrate for the first time that WS2 nanosheets exhibit ultrafast nonlinear saturable absorption property and high optical damage threshold. Soliton mode-locking operations are achieved separately in an erbium-doped fiber laser using two types of WS2-based saturable absorbers, one of which is fabricated by depositing WS2 nanosheets on a D-shaped fiber, while the other is synthesized by mixing WS2 solution with polyvinyl alcohol, and then evaporating them on a substrate. At the maximum pump power of 600 mW, two saturable absorbers can work stably at mode-locking state without damage, indicating that few-layer WS2 is a promising high-power flexible saturable absorber for ultrafast optics. Numerous applications may benefit from the ultrafast nonlinear features of WS2 nanosheets, such as high-power pulsed laser, materials processing, and frequency comb spectroscopy.

Direct growth of graphene on quartz substrate as saturable absorber for femtosecond solid-state laser

We present a novel method for the direct metal-free growth of graphene on quartz substrate. The direct-grown graphene yields excellent nonlinear saturable absorption properties and is demonstrated to be suitable as a saturable absorber (SA) for an ultrafast solid-state laser. Nearly Fourier-limited 367 fs was obtained at a central wavelength of 1048 nm with a repetition rate of 105.7 MHz. At a pump power of 7.95 W, the average output power was 1.93 W and the highest pulse energy reached 18.3 nJ, with a peak power of 49.8 kW. Our work opens an easy route for making a reliable graphene SA with a mode-locking technique and also displays an exciting prospect in making low-cost and ultrafast lasers.

Sapphire-based graphene saturable absorber for long-time working femtosecond lasers.

We report a long-time working femtosecond laser using metal-free sapphire-based graphene as a saturable absorber (SA). The sapphire-based graphene yielded excellent nonlinear saturable absorption properties and was demonstrated to be suitable as an SA for an ultrafast solid-state laser. Stable mode-locked pulses of 325 fs were obtained at a central wavelength of 1032 nm with a repetition rate of 66.3 MHz. At pump power of 8.23 W the average output power was 1.78 W and the highest pulse energy reached 26.8 nJ with a peak power of 72.6 kW. Our work opens up a facile route for making reliable graphene SA in the mode-locking technique and also displays an exciting prospect in making low-cost and ultrafast lasers.

硒化铅量子点聚乙烯醇薄膜的三阶非线性光学特性

PbSe/polyvinyl alcohol composite film with third-order nonlinear optical property was prepared by wet-chemical method.The morphology of the PbSe nanocrystals was characterized by transmission electron microscope,and the surface morphology of the composite film was characterized by scanning electron microscope.The third-order optical nonlinearity of film was investigated by using the laser Zscan technique with 38ps pulses width at 532nm.The experimental results show that the diameter of PbSe nanocrystals is about 10nm,which is in strong quantum confinement regime,and the film has a flat surface.Negative nonlinear refraction and reverse saturable absorption properties were observed,the third-order nonlinear refractive indexχ(3)was found to be 3.6×10-11 esu.