Studies On All-fiber Photonic Crystal Fiber Amplifier

Due to its dual advantages in structure and performance,fiber lasers have become one of the hot topics in the optoelectronics field in recent years.The emergence of the large mode field double clad fiber greatly improves the laser output power,but reduces the beam quality.The emergence of double-clad photonic crystal fiber,while the core mode field diameter can be further increased,but also to ensure the core laser mode operation,which in order to achieve high peak power,high beam quality pulse laser has opened up a new Way.However,due to the photonic crystal fiber's hole structure,so that the application began to use more space structure,stability and reliability are low.In this paper,we focus on the all-fiber amplifier based on photonic crystal fiber,improve the stability of the whole system,reduce the threshold of photonic crystal fiber,and lay the foundation for a wide range of application.The research work of this thesis mainly includes the following aspects:1.Fully study and summarize the fabrication method of end signal / pump combiner,follow the principle of adiabatic tapering and brightness conservation,learn the design and production process of end signal / pump combiner,and lay the theoretical and experimental foundation for achieving all-fiber photonic crystal fiber amplifier.2.The use of domestic photonic crystal fiber to complete the production of all-fiber photonic crystal fiber amplifier.Using the CT-106 cutter to complete the cutting of photonic crystal fiber,through the continuous adjustment of parameters to achieve a small angle cutting.Through a large number of experiments,master the photonic crystal fiber cutting techniques.The use of casing method,completed the photonic crystal fiber end signal / pump combiner production.Master the end signal / pump combiner production process and operating skills.We successfully splice the tapered fiber bundle to photonic crystal fiber and the photonic crystal fiber amplifier has completed.The amplifier is tested and analyzed.3.The use of NKT Photonics 40/200 / 450?m(NA = 0.03 / 0.60)double cladding ytterbium-doped photonic crystal fiber to complete the production of fiber amplifiers using the existing cutting and welding technology.The signal fiber is used as the ordinary single mode fiber SMF-28,and the pump fibers are 105 / 125?m(NA = 0.22).multi-mode fibers.Complete the photonic crystal fiber cutting and welding work,and to achieve photonic crystal fiber with end cap welding,to achieve all-fiber photonic crystal fiber amplifier.Based on the fabricated amplification module,we achieved a laser output of 108.1 W with a slope efficiency of 72.7%.The conversion efficiency of the amplifier,the output spectrum and other parameters are measured,and we design refrigeration fixture to realize the modularization.