The Research On Quasi-Shaping Technique Of Aspheric Lens Group For High Power Semiconductor

As a new type of light source in space communication, semiconductor laser has the advantages of simple structure, small volume, long life and low price.However, due to its own structural problems, the active width of the side-emitter semiconductor laser is much larger than the thickness, so that the divergence angle is asymmetric parallel to the junction plane and perpendicular to the junction plane. In the far field showing long and narrow elliptical spot, and with the initial astigmatism, poor beam quality, seriously affected the application of semiconductor lasers.In recent years, many scholars or scientists at home and abroad are committed to the laser beam shaping collimation technology, looking forward to improve the beam quality and energy efficiency.In applications where alignment accuracy and energy requirements are not high,low-cost spherical lens groups can be used to achieve collimation of the beam, whereas for those applications where alignment accuracy and energy requirements are relatively high, the aspherical lens has the advantage of being irreplaceable, so this paper proposes two collimation schemes based on aspheric lens. One is the combination of two aspherical lenses. The front surface of the first lens realizes the collimation of the beam, the rear surface and the second lens compress the fast axis beam. The second design is a special lens with a lens and prism. The front surface is used to collimate the beam, and the rear surface is used to compress the fast axis beam. The main work of the paper is summarized as follows:(1) This paper summarizes the research background and significance of semiconductor lasers as a new type of energy in space communication and its development history and current research on laser beam collimation.(2) The working principle, beam characteristics and beam quality evaluation parameter of the semiconductor laser are described. It is pointed out that the semiconductor laser beam is a Gaussian beam with the initial astigmatism, the propagation law of the Gaussian beam and the collimation theory of the Gaussian beam are discussed. Some classical collimation schemes and advantages and disadvantages are summarized.(3) Two collimation schemes of high power laser beam with aspheric lens are proposed.Each design is analyzed from the sagittal plane and the meridional plane respectively, and the surface parameters of each aspherical lens are deduced. Program design using MATLAB simulation. The results show that each scheme achieves the ideal collimation effect in theory, that is, the collimation of the laser beam is realized, which eliminates the inherent astigmatism and improves the energy efficiency.(4) The two quasi-shaping schemes are systematically analyzed, such as the selection of lens materials, the influencing factors of collimation effect and the energy distribution of laser beam through the system.