Research On Er³⁺:ZBLAN Dual Band Fiber Laser Based On Composite F-P Cavity

Mid-infrared lasers in the 3μm and 2μm bands have good application prospects in laser detection,optoelectronic countermeasures,space communications,scientific research and experiments.In terms of medical surgery,since water has an absorption peak at each of the 2.8μm and 1.6μm bands,a 2.8μm laser can be used for precise tissue cutting,and a 1.6μm laser can coagulate and stop bleeding,so a laser beam containing these two components can be used In surgical minimally invasive surgery.At present,the commonly used method for obtaining 2.8μm and 1.6μm laser beams is to use two independent lasers for coherent beam combining.This solution has a complicated system structure,a large volume,high cost,and low reliability.In this paper,a cascaded oscillation method is used to develop a fiber laser with a single working medium output of 2.8μm / 1.6μm dual-band.Based on the research of the 2.8μm / 1.6μm dual-band Laser operating mechanism,the following research and experiments have been carried out.First,a complete mathematical model is established based on the rate equation and the energy level system of Er³⁺ ions.The model is simulated with MATLAB.In order to improve the accuracy of the simulation,a genetic algorithm is innovatively written to solve the model to obtain a suitable Er³⁺:ZBLAN fiber laser Parameters of each part.Secondly,a single pump source and single working medium Er³⁺:ZBLAN fiber laser is designed and built on the basis of simulation calculation results The Er³⁺:ZBLAN fiber was back pumped with 976 nm LD,and the fiber length is 10.5m and doping concentration is 1mol.% Form a composite F-P cavity.With a pumping power of 50 W,cascade laser outputs with center wavelengths of 2.789μm and 1.599μm were obtained.The laser powers were 8.19 W and 2.8W,and the corresponding slope efficiency was 17.7% and 7.17%.The peak power fluctuation ratios within two hours are 4.6% and 3.1%,respectively.Finally,a single-point ablation experiment was performed on the pig epidermal tissue with a built-in dual-wavelength fiber laser.The experimental parameters are: laser power 0.5W,1W,1.5W,2W;irradiation time 5s,10 s,15s,20 s.The comparison results of the parameters of the 10.6μm CO2 laser show that the ablation effect of the 2.8μm laser is better than that of the 10.6μm CO2 laser,and the 1.6μm laser has a good coagulation effect on the tissue.