The Study Of The Coupling Of High Power LDA And Fibers

Coming with optical communication age, LDA (Laser Diode Array) is moreand more applying in the military affairs area, medical treatment, materialprocessing and so on, for it is small, durable, high transition efficiency of light andelectricity, high output power density and other advantages. From the first fibertransmit equipment which was used in material machining come out in 1985 tonow when some countries in US have transmitted the laser of the power of 10KW,and it have received the output power of 6KW in products. However the fibercoupling module of the output power of hundreds watt are researching in ourcountry.Because of the limitation of the structure of the LDA (the dimension of theactive area is150 μ m × 1μm), it has the large radiation angles and great opticalaberration, so it must to be shaping. Using micro-lensed technique to compress theradiation angle from all direction, we will be able to reach the higher output powerand get the smaller photospheric, and then the loss of the coupling will be muchless and the distance of light-transfer should be much longer. We discuss the ideafrom five aspects.1. The advantages and the necessary of fiber coupling were introduced, andalso the history, the existing state of coupling technique in all of world and itsapplications were presentationed.2. For the limitation of the application of the LDA was caused by the highlydissymmetry of the radiation field, the configuration of the LDA and thecharacteristic of the radiation beam were discussed.3. According to the importance of fibers in laser beam sharping, theconfiguration of fibers was introduced, also the conditions and the factors werestudied for the low loss of the fibers where the laser beam traced.4. Some main beam sharping technologies were summarized, and theoperation mistake and some different ways to deal with the heads of fibers in thetechniques of beam sharping were analysed.5. Two beam sharping modes were designed. First, it was the coupling ofhigh output power LDA and fiber array. It could reach the output power of 30W,and the efficiency of coupling was 75.1%. Second, it was the coupling of the highoutput power LDA and a single fiber. The finally output power was more than 30W,and NA was 0.22.The coupling technology of LD Bar and fiber array in our country has reacheda very high level. However with the development of the industry, the LDA of morehigh output power will be needed. LDA will be made of much more LD which iscalled LD Stack. If we remain used the coupling mode of fiber array, the results arelaser-spot size will enlarge, and the brightness will descent. So the coupling ofLDA and a fiber is the best of all, and it will be the director of the couplingtechnique. So in the future, the emphasis of our work include preparing the LDAwith much higher output power, designing simple and effective beam sharpingmodule, and research the fibers with the high damage threshold.