Research On High Power Ytterbium-doped Fiber Laser

Stimulated radiation theory was proposed by Albert Einstein in 1917 and after that people have stepped on the road to laser.Theodore H.Maiman and others developed the first ruby laser of the world in 1960.Since then,great achievement in lasers were achieved in more than 50 years and a variety of lasers including gas lasers,semiconductor lasers,solid lasers,and so on,have been developed.Fiber lasers have attracted considerable attentions due to many merits such as high efficiency,high spatial quality,compactness,low manufacturing costs and so on,which have become a key new generation of lasers with a broad application prospect in the fields of national defense and industrial processing.Among them,the ytterbium-doped fiber lasers have been relatively mature and have achieved great success in commercial applications.In recent years,due to the development and improvement of double-cladding fiber,high-power fiber lasers are still the focus of research.On the one hand,people are pursuing continuous breakthroughs in fiber lasers' power limitations.On the other hand,some subdivided fields require high power and high laser coherence at the same time,so we need to develop narrow-width high-power fiber lasers.This thesis focuses on ytterbium-doped fiber lasers,focusing on continuous narrow-width high-power fiber lasers and pulsed fiber lasers.The specific research content is divided into three parts:1?Design and production of the pump light source driver.A driver circuit is self-designed and fabricated,and a STM8 one-chip computer is adopted as the central microprocessor which realize the control of driving of the pumping light source through programming.The driver may be remotely controlled by a computer,or the by local buttons together with a display panel.The driver controls the temperature and the current of the pump light source so as to achieve different laser output powers,among which the temperature control accuracy is ± 0.1 ?.2.Research on continuous narrow-linewidth high power fiber laser.(1)A domestic fiber laser simulation software was used to optimize the length of the gain fiber in the laser and evaluate the output power.(2)The structure of continuous narrow-line high power fiber laser is a seed laser diode(LD)plus double optical amplification structure.A narrow linewidth LD is used as a seed light source,and a home-made driver is used to realize the current driving and temperature control of the seed light source.The seed light is subjected to a secondary optical amplification and a 976 nm pump light source is used in the optical amplification structure.A double-clad ytterbium-doped fiber in the second-stage optical amplification structure.After a second-stage amplification,pulse lasing output at 1064 nm with a power of 14.8 W and a linewidth of 3 MHz.3?Research on pulse fiber laser.We use fiber Bragg grating feedback and structure of Q-switched to set up pulse seed source where the gain fiber is home-made.A 915nm pump LD is used to achieve 1064nm lasing and the output power of the seed fiber laser is more than 1W.After a Master Oscillator Power-Amplifier(MOPA)structure,the output power of the pulse fiber laser is 10.2W together with the pulse width of 300-500ns and the pulse repetition rate from 20kHz to100kHz.