Research On The Key Technologies Of Mode Generation,Multiplexing And Control

Entering the 21st century,human society is stepping gradually from the information era into the data era.With many new businesses and technologies constantly emerging,data business has been continuously growing at an explosive speed,and the existing optical fiber transmission resources are being rapidly consumed.Therefore,demands for expanding the transmission bandwidth and improving the information transmission capacity become increasingly urgent,and seeking a new fundamentally solution of the bandwidth demand contradiction is imminent.Space division multiplexing,which based on space,a new physical dimension,is not limited by nonlinear Shannon limit,therefore,has great potential,and becomes a hot technology expected to solve the channel capacity problem.Mode division multiplexing is a kind of space division multiplexing technology.It uses the orthogonality between modes in the multimode fiber,with different modes as independent channels carrying different information,to propagate simultaneously in the optical fiber.Based on"The National Key Basic Research Development Plan(973 Plan)" project"Multi-dimension multiplexing optical fiber communication basic research",this dissertation studies some key technologies of mode generation,multiplexing and control,and the main content of the research is mode switching and multiplexing in free space.The main research contents of this paper are as follows.First,the derivation and verification of free space mode switching and multiplexing principle.The emphasis is laid on the mode theory model in graded-index fiber and step-index fiber,thus laying the theoretical foundation for the selection of corresponding devices to build experimental platform.Second,the set up and improvement of experimental platform.Using the existing phase plate and spatial light modulator,the free space mode switching and multiplexing optical system was designed and built based on the 4f system,and improved by using methods like high frequency filtering and super pixel.Then the SLM based spatial mode generation system was optimized and improved with the simulated annealing algorithm.Third,the exploration of new kind of spatial mode conversion,multiplexing and demultiplexing system.The working principle of multi-plane optical conversion system was studied,and the optical paths were designed,emulated and analyzed.Then the comparison of this system with the traditional spatial mode conversion system was made.