Design And Research Of High Power YB Fiber Laser

With the emergence of various new kind of optical fiber element,他the technology of high power fiber laser producing gets to mature gradually, its related products also get into the fields of industry, military, medical equipment, etc more deeply. Because of the small volume, high conversion efficiency, more centralized energy compared to other high power laser, fiber laser draws more and more attentions from the manufacture and scientific research department. The main research contents and innovation are as follows:1. Using scalar method of linear polarization mode, study fiber coupling process, according to the optical fiber characteristic parameters U, W, calculate coupling coefficient of different fiber modes, and then combined with optical fiber power distribution function, the optical power transmission in fiber is studied. This paper carries out a calculation method of multimode optical fiber coupling numerical analysis, according to fiber parameter, calculate coupling efficiency and fiber coupling length while the main factors influencng fiber coupling is pointed out.2. After theoretical deducing and numerical simulation of absorption characteristic formula of double cladding fiber, based on the analysis of the optical fiber doping concentration, mode field diameter, fiber loss, etc, the factors influence the optical fiber gain, the structure of double cladding Yb fiber laser is designed. Use the analysis result to choose reasonable gain fiber, determine the fiber length, core diameter and absorption rate, etc. At the same time, choose matching fiber components, complete preliminary design of system structure.3. According to Yb fiber absorption spectrum characteristics, carry out the theoretical analysis near the wavelength of976nm in the pump laser, the FBG reflection characteristics and WDM spectral characteristics are studied, simulate the effects of grating length and grating tuning amount to its performance. According to the results of analysis, design pump laser work wavelength control system to improve fiber laser pump efficiency. Designthe full optical fiber wavelength detector with the use of WDM with short half wave oscillation cycle, detect pump laser output wavelength, on this basis, design a kind of pump laser control structure, in order to improve optical conversion efficiency.4. Study the principle and working characteristic of main optical components of fiber laser system, such as Yb fiber, pump laser, combiner, according to experimental purpose and total target, design the fiber laser structure. Apply the MOPA structure with seed source of pulse driving and two level amplifier, finish experimental and theoretical verification in915nm pumping. Complete prototype development with the MOPA strcture that first level of pulse laser using AOM, second amplified level. Test various operation indexs of915nm pumped fiber laser and976nm pumped fiber laser, optical conversion efficiency, pulse shape, the line width and so on.5. Complete the prototype development of20W fiber laser with pulse output, select the structure of pulse output with976nm pump, combined with optimizing design of pump laser control, control the pump wavelength and improve the pump efficiency. System repetition frequency can be adjusted, average power is stable, single pulse energy is high and the free maintenance operation is achieved.