Research On Beam Control Theory Based On Multi-Plane Light Conversion

Multi-plane light conversion(MPLC)is widely used in the field of beam control.It can be seen in the aspects of mode multiplexing,spatial optical communication,laser focus control,quantum communication and so on.In this paper,the theory and key technologies of optical fiber mode multiplexing and demultiplexing technology based on multi-plane optical conversion are studied.Main contents and innovations of this paper are as follows:1.Mode multiplexing MPLC system is designed basing on the Wavefront matching algorithm.The coupling efficiency of the traditional HG mode multiplexing MPLC which has a triangular input arrangement is studied.Simulations prove that the frontal difference of the coupling efficiency between different modes is related to the number of related modes of the target mode.An improved arrangement based on increasing the number of related modes in HG mode multiplexing MPLC system is proposed.Compared with the traditional triangular arrangement,mode dependent loss is increased from-1.21dB to-0.4dB.2.The important parameters in HG mode multiplexing MPLC system,including pixel size,plane spacing,waist diameter of the input spot,input arrangement and other parameters which have influence on insertion loss and mode dependent loss of the MPLC is studied in this paper.And parameters are optimized in this paper.3.A beam encryption method basing on MPLC is proposed and simulated.The realization of encryption conversion and encryption multiplexing is realized via MPLC.After setting reasonable parameters,MPLC can achieve high performance.Insertion loss achieves above-0.5dB and mode dependent loss achieves above-0.15dB.The sensitivity of the wavelength error and the plate spacing error of the MPLC encryption system is studied.The performance of the system was stable in the wavelength range of 1549.5nm-1550.5nm and the plate spacing range of 24.99mm-25.01 mm.