The Study On Improvement Of The Beam Quality Of High Power Diode Laser Array

Because of high power, high efficiency and long lifetime, diode laser have applied to many fields as communication,medical,diode pumped solid laser and military. Especially in material processing fields, high power diode laser arrays have replaced conditional solid-state lasers. But diode laser suffer from a poor beam quality, which limit their direct application. So how to improve the beam quality of diode laser have become of the focus in the world.The main thesis of this work is to improve the beam quality and enhance the brightness of diode laser arrays. Base on the methods of beam quality improved overseas. Using plan-concave columnar mirror and volume holographic grating as the external cavity to improve the beam quality. To further meet industrial applications. High power diode laser stack fiber coupled has been studies also.Coherent combination make the diffractive fields coupled between elements by external feedback. For reducing the self-coupling coefficient from the external cavity, Use the plan-concave columnar mirror as the external cavity and locate the semi-conf -ocal cavity with the theory analysis and experimental studies. The spectral width of diode laser narrowed from 2.5nm to 0.5nm. Improve the coherent characteristic great- -Ly. Besides, for stabilize the wavelength of diode laser array, First use the volume holographic gratings to improve the spectral properties in our country, and experimental study have been carried out, spectral width was narrowed to 0.22nm, wavelength shift with the tempreture was reduced 0 .01nm/C~0.At last,Innovately use the VHG and plan-concave make up of external complexed cavity, gained the double wavelength, center wavelength speration contained 1.8nm all the time, spectral width narrowed to 0.2nm.Recently, with the beam quality increased and the beam shaping improved. The diode laser with the fiber coupled developed rapidly in materials processing. And applied to deep penetration welding. Using the step refletive mirror to increase the fill factor, It is effective to eliminate the dead region, Improve the beam quality of diode laser stack. At last, further projected the method coupled the beam of diode laser stack into the fiber with core 800um, NA 0.22.