Research On The Cladding Light Stripper In High Power Fiber Laser

With the output power of the fiber laser and amplifier which using cladding pump technology reached kilowatt level,in order to maintain the beam quality of fiber laser at a high level,there are some new technical problems,a very important one is the "unwanted" residual light appear in the cladding of optical fiber.These "unwanted" light residues in the cladding of the fiber,if not timely removed,will not only affect the beam quality and monochromatic laser output,but also cause damage to the output device,it is directly related to the safe and stable operation of high power fiber laser.In order to improve the stability of high power fiber laser’s beam quality,spectral characteristics and fiber laser systems,a new type of cladding light stripper was designed,investigates the stripping method for the residual cladding light of high power fiber lasers.Firstly,this paper introduces the cladding pump technology and double clad fiber,analyzes the sources,magnitude and characteristics of residual cladding light in the double clad fiber laser,and a new type of cladding light stripper was designed.Using the Monte Carlo algorithm and The light trajectory tracking method to calculate and evaluate the performance of the cladding light stripper,analysis the principle of traditional cladding light stripper which using high refractive index gel,analyzes the influence of the refractive index of the recoated gel and different divergence angle on the filtering effect,and evaluates filtering effect of the new cladding light stripper and its optimization model.Then use the CFD module in ANSYS software,modelling the thermal simulation of the cladding light stripper,doing theoretical research and analysing the boundary conditions,simulation analysis temperature field of the cladding light stripper,under the input power of 100W-600 W.The results show that,the hot spot temperature of the cladding light stripper is reduced by 20.8℃,under the input power of 600 W,and the uniform filtering of the optical power is realized.Finally,this paper describes the fabrication process of the cladding light stripper,including the removal of the optical fiber coating layer and the solidification of UV curable adhesive.The experimental environment of the prototype of the cladding light stripper is set up.By adjusting the output power of the semiconductor laser,it is proved that the extinction ratio of the cladding light stripper is more than 18 dB.