A molybdenum disulfide (MoS2) saturable absorber (SA) was fabricated via the liquid-phase exfoliation method. The optical properties of MoS2 were systematically characterized and the modulation depth was measured to be 6.2%. A laser-diode-end-pumped, passively mode-locked Nd : YVO4 / PPLN green laser with a SA based on few-layered MoS2 was successfully demonstrated. The pulse width of the stable continuous-wave mode-locked laser operating at 532.1 nm was 3.5 ps, and the pulse repetition frequency was 87.2 MHz. The maximum average output power of 757 mW was obtained under an absorbed pump power of 8.62 W. The calculated single pulse energy and peak power were 8.7 nJ and 2.49 kW, respectively.
A multiwavelength midinfrared quasi-phase-matched (QPM) difference frequency generation (DFG) scheme is proposed based on a segmented temperature controlling technique for the uniform grating periodically poled lithium niobate (PPLN). The QPM DFG output performances have been investigated under the fixed pump and signal wavelength conditions, respectively. Our theoretical results show that when the pump wavelength is fixed at 1.08 μm, three idler QPM bands, located at 3.46, 3.50, and 3.57 μm, have been obtained, where the temperatures of the three PPLN segments with the same length are set at 20°C, 70°C, and 100°C. However, when the signal wavelength is fixed at 1.58 μm, six idler QPM bands, located at 2.95, 3.06, 3.14, 3.63, 3.72, and 3.83 μm, have been achieved with the same crystal temperature distribution of 20°C, 70°C, and 100°C.
The characteristics of pulse laser transmitting in atmosphere were analyzed. An experiment setup was introduced to
measure the impacts of fog produced by ultrasonic-nebulizer on time delay characters of the laser pulse transmission in
atmosphere. The experimental results show that the width of laser pulse becomes wider while the laser pulse transmits in
fog. The value of width broadened increases with the enhancement of fog thickness. The value of width broadened is
substantially proportional to the extinction coefficient. The R-square of curve fitting is 0.9777. This relation may be used
to estimate the atmosphere extinction.