Fiber cladding mode stripper is one of key devices in high-power fiber lasers and high-power transmission fiber. We report a new kind of mode stripper using quartz tubes with etched dots on the surface. We studied the waveguide property of the mode stripper both the dots on the outer surface and on the inner surface of the tube. Then we produced some quartz tubes using green laser for the experiments, which demonstrated that the new model strippers can reduce the cladding light and improve the axial temperature distribution obviously.
We present a laser beam shaper designed to obtain a homogeneous line beam. A beam shaping system was designed based on cutting and rearranging optics, using two groups of plane parallel plates. The analysis of beam uniformity was performed by use of ray tracing simulation through ZEMAX software and experimental validation. The simulation results show that in the focal plane, a beam width of 1 mm (@95%Imax) and a uniformity of 90.2% are achieved in one direction, and a Gaussian profile with a beam width of 0.06 mm (FWHM) is achieved in the other direction.
A model of deicing with Nd:YAG and CO2 lasers for simulation using ANSYS software is presented. Experiments with a 300-W, 1-ms, 60-Hz Nd:YAG laser and a 500- to 2000-W cw CO2 laser are reported. The Nd:YAG laser is considered as a volume thermal source, and the CO2 laser as a plane thermal source. The model and the simulation results can describe both Nd:YAG and CO2 laser deicing well. The results of the simulation and experiments suggest that the melting rates for the two lasers are almost equal at the same laser power density. So are the melting efficiencies. The hard and transparent ice irradiated by the Nd:YAG laser becomes opaque and loose, because the thermal stress is distributed in the body of the ice, while the ice irradiated by the CO2 laser is still transparent and hard, because thermal stress hardly occurs. So the laser with characteristics of high output power and large ice absorbing length can be selected for the power line laser deicing system, and Nd:YAG laser is more appropriate for power-line deicing than CO2 laser.
Based on the theoretical model of uniform pulsed laser beam irradiating on the optical material, the stress
distribution of the transparent material when laser with different beam spatial distribution - circle beam spot and
dark-cross beam spot - irradiated to the inner of optical material was discussed.
The experiment that 532nm Q-switched laser pulse was focused to the inner of silicate glass was taken, which the
beam spatial distribution of the output laser was dark-cross beam spot. According to the theory, the experimental results
and phenomena were analyzed and the damage micro-configurations were explained. The theory and experiment could
be accordant well.
Under the normal temperature, Nd:YAG crystal has three fluorescence spectrums, the strength of 1.06 micrometers spectrum is nearly 4 times to that of 1.32 micrometers 's, only by selecting frequency method, 1.32 micrometers oscillation can be obtained. Modulating the 1.32 micrometers wavelength and doubling its frequency, 0.66 micrometers the SHG of 1.32 micrometers can be output. In this experiment, we obtain 23.7 W 1.32 micrometers maximum laser output and 500 mW 0.66 micrometers red laser output.