Study Of Tunable Output Characteristics Of Yb³⁺-doped Ring Ifber Laser

With the development of the optical fiber manufacturing process andsemiconductor laser production technology, optical fiber laser based on optical fiberhas got obviously advances in reducing threshold, oscillation wavelength range,tunable wavelength characteristics, which has already become a new technology inthe field of laser application and has been studied by many researchers.In this paper, we first introduce the valuable significance of optical fiber laser;then we talk about the development history of mode-locking fiber laser at home andabroad; at last, we summarize the future and potential application of mode-lockingfiber laser. We roundly elaborate the double cladding structure, characteristics,developing situation, double cladding principle, mode-locking principle of passivemode-locking optical fiber laser based on nonlinear polarization rotation effect. Then,we analysis the different characteristics of laser system working at linear region andnonlinear region, discuss the relation between each parameter derived frommode-locking time domain equation, which has been the theory support of our opticalfiber laser system and the experimental phenomenology analysis. Next to what wetalk about before, we introduce our experimental apparatus. There is a solenoid withdiameter34mm between isolator and left collimating lens, closely twine the solenoidwith different length1060-XP single mode optical fiber respectively, the length ofoptical fiber is75cm,3m and7m.We then analysis the tunable wavelength, poweroutput and mode-lock characteristics of this system. We find that solenoid twined withoptical fiber has great influence on this system which can extend the range of lasertunable wavelength. Compare to75cm length fiber, solenoid twined with3m or7moptical fiber has a little enhanced tunable range, this confirm that the length of thetwined optical fiber is not the longer the better, it also can bring great additional loss, as a result the slope efficiency and the frequency of pulses are reduced. We choose7m optical fiber as the twined length, the diameter of the solenoid is25mm,34mmand48mm.We then analysis the influence of solenoid size on system performance,experiments indicate that there is none noticeable change of system performance withdifferent solenoid size. However, there should be a best scheme which can optimizeeach characteristics of system, this need more careful work, and we should havespecific theory analysis of double refraction effect and system loss.In this thesis, we intensively study the tunable characteristics of Yb³⁺doped ringoptical fiber laser and get some valuable experimental results. What is more, we findsome phenomenon which deserves farther study.