Research On Diode Laser Linear Array Combining Source And Wavelength Beam Combination With External-cavity Feedback

Diode lasers possess many outstanding advantages, like high conversionefficiency, long lifetime and so on. However, due to the special structure, its beamquality is so poor and its power density is so low that it is difficult for a diode laser tobe as a direct laser source applied in the fields of material processing and nationaldefense. How to obtain a diode laser source with both high power and high beamquality has become an international major bottleneck, which has been listed in thestate-level program by many countries such as America, Germany. The technology oflaser combining has been proven to be a key solution to conquer it. The USA wants todemonstrate a100kW, with near-diffraction-limited beam propagation by combiningthe beams of high power, high efficiency laser diodes for the tactical applications.Germany has developed a series of high efficiency and energy saving laser processingmachines by diode laser combining, applied in the field of industrial manufacturing.In this paper, the high power, high beam quality diode laser sources areresearched from two aspects of tradition beam combination (TBC) and wavelengthbeam combination (WBC) with external-cavity feedback, and the main accomplishedwork as follows:1) A beam shaping method of beam compression with a single component is putforward to improve the beam quality by a factor of about one, licensed1inventionpatent. A diode laser source with a CW (continuous wavelength) power of500W anda beam quality of12.4mm·mrad is designed and developed, and the result is publishedin the Chinese journal of laser vol.40,2013.2) To meet the demand of industrial application, a fiber coupling diode lasersource with a CW power of935W and a fiber diameter of600μm is developed forflexible processing. And it is successfully applied to sheet metal welding as a direct light source, which has not yet been reported in domestic after the novelty search. Theresults are published in Chinese journal of laser vol.39,2012. On the basis of theabove result, three methods of rail cleaning, rail repairs and wire cleaning by diodelaser source are presented, and3authorized invention patents are licensed.3) A novel structure of wavelength beam combination with external-cavityfeedback based on the transmission grating is first proposed and implemented. Adiode laser source spectrally combined by a single bar is developed with a CW powerof50.8W and a beam quality of3.34mm·mrad, published in Optical Express vol.21,2013, and “The coupled output power is very higher and the beam quality is muchbetter than others”, evaluated by the reviewer.4) Two laser sources with wavelengths of800nm and970nm are developed,respectively, each of which is combined by three bars with WBC. The conclusion isinferred that the WBC structure is suitable for the emitters with any differentwavelength. Besed on the above, the structure combining WBC with TBC is furtherproposed.