Study On Spectral Beam Combining System Of Semiconductor Laser With External-cavity Feedback

External cavity feedback spectral beam combining technology is a kind of beam combination based on the dispersion element,which makes each incident beams overlapped,and realizes the combination of the close field and the far field.It is an effective method to improve the beam quality and the output power.There are still some shortcomings.First,the quality of the combination beam can't be completely equal to the beam quality of a single emitting unit.Second,the spectral combining efficiency is not high.Third,the spectral broadening of the output beam is the sum of the spectrum of all the emitting units,which broadens the output spectral bandwidth.This paper focuses on the problem of low beam combining efficiency and wide output spectrum.In order to improve the output power,the combining efficiency model of the spectral beam combining is established.The influence of three parameters,namely,the focal length of the lens,the diffraction efficiency of the grating and the reflectivity of the output coupling mirror,on the combining efficiency are analyzed.Design a high combining efficiency of external cavity feedback spectral beam combining structure.To narrow the output spectral bandwidth,two kinds of beam shaping system are designed.One is a 5 times compressed prism consisting of two right angled prisms,and the other is a 5times reverse Galileo lens group.The theoretical spectral broadening are 2.54nm and 2.88nm respectively.Then two ways to verify the traditional and improved spectral beam system are also carried out.First,build the optical transmission model to simulate the beam distribution after the beam combining.The beam of the M~2=3.2 beam is obtained.The effects of two grating parameters the ridge height and the duty ratio on the beam characteristics are simulated.The second method is using the non-sequence mode of ZEMAX optical software to simulate the overall structure of the spectral beam system.The beam combining efficiency of 90.8%and M~2=1.27 are obtained.The two methods have proved that the beam quality of the improved beam combining system is higher than the traditional beam combining system.