Engineering Research And Application Of Soft Edge Aperture High Power Solid-state Lasers

Converting Gaussian to super-Gaussian beam is the key for ulteriorly improving the power of laser systems. Soft aperture apodization is one of the effective ways to get super-Gaussian beam. But it’s not yet completely practical in high-power lasers because of the design and fabrication methods. This paper gives the design and fabrication methods of serrated aperture and glass soft aperture based on diffraction theory of soft aperture for getting super-Gaussian beam, and verifies the correctness of design and effectiveness of fabrication methods by means of typical cases.This paper establishes numerical model of serrated aperture in conjunction with spatial filter based on Fresnel diffraction theory, and discusses the influence of different parameters of serrated aperture on the output beam by virtue of numerical calculation. Based on this, we give systemic design method and typical case and fabricate the serrated aperture in a thin copper material sheet using the high-power fiber laser. We compile diffraction experiments for getting super-Gaussian beam with serrated aperture in conjunction with spatial filter in the SGR-Extra laser system of "Beijing Beamtech Optronics Co., Ltd.". The results agree well with the design requirements, and achieve expected goals. Similarly based on the soft aperture scalar diffraction theory, the paper also gives the design method of glass soft aperture and introduces the laser engraving process method achieving the processing of typical case. Applied in the Nimma, and Vlite series lasers, these results show that using glass soft aperture can reliably weaken or even disappear hot point, ease up diffraction rings and make whole spot more uniform. The application in Vlite series lasers also show that glass soft aperture can increase the second harmonic(532nm) energy more than40%without any damage of KTP crystals.