Optimal Design Of M×N Wavelength Selective Switch Based On Dual Prism Beam Expansion Syste

Wavelength selective switch(WSS)have a wealth of all optical signal processing functions such as colorless,directionless,contentionless,gridless.They are the key core devices in current reconfigurable optical add/drop multiplexing(ROADM)optical networks.With the continuous and rapid growth of network capacity and scale,ROADM node devices based on 1 × N-port WSS face prominent technical issues such as complex system composition,numerous devices,high construction and operation maintenance costs,and high power consumption.To address these issues,further research and development of a new generation of ROADM devices based on M ×N-port WSS has become an industry consensus.However,due to the technical complexity of the M ×N-port WSS itself,this research is still in the laboratory research stage and there is no commercial product available.Aiming at the main technical difficulties of current M×N-port WSS,such as complex optical systems and high insertion losses,this paper proposes a simplified system design scheme for a refracting-reflecting M ×N-port wavelength selective switch based on a biprism beam expander system.By establishing a ZEMAX simulation model,the overall optical system is simulated and designed;An experimental system for M ×N-port WSS was established to verify the effectiveness of the proposed system scheme.The main tasks completed in the thesis include:1.Aiming at the prominent problems of the large number of M ×N-port WSS components and the complexity of optical systems at the current stage,a new M xNport WSS technology scheme is proposed based on the idea of extremely simplifying optical systems.The main innovation points are as follows:(1)The design of a refracting-reflecting system structure reduces the size of the entire system by half,greatly reducing the use of optical components,which is conducive to reducing system insertion losses;(2)The design scheme of a biprism beam expansion system is adopted to effectively control the internal transmission beam and port of the system as well as the light spot on the liquid crystal;(3)Using a small focal length cylindrical mirror design,while suppressing system aberration,it alleviates beam divergence on the liquid crystal and increases the number of port light spots that can be arranged on the liquid crystal.2.The key optical components such as fiber collimator port array,biprism,cylindrical mirror,diffraction grating,and mirror,as well as the design scheme of M×N-port WSS system based on biprism beam expansion system were simulated and studied by ZEMAX.Various parameters were optimized,and the switching of optical signals between six ports was realized through simulation.3.An experimental prototype of a M ×N-port WSS optical system with six input/output ports was built.Using the middle two ports as inputs and the other ports as outputs,the experimental verification of switching optical signals between different ports is achieved.The system has a minimum interport insertion loss of 10 dB,a spectral adjustment accuracy of 16.5±1 pm,and a minimum channel bandwidth of 16.3 GHz.The work in this paper shows that the proposed design scheme of a refractingreflecting M ×N-port WSS optical system based on a biprism beam expander system not only greatly simplifies the optical system design of the wavelength selective switch,effectively reduces the number of optical components required,but also achieves all wavelength switching functions of the M ×N-port WSS,achieving a good experimental result with a minimum insertion loss of 10 dB and a minimum channel bandwidth of 16.3 GHz.Through further optimization of key optical components and optical paths,the adoption of this technical solution is expected to achieve greater breakthroughs in port numbers and system performance,which will positively promote the development of M ×N-port WSS and the new generation of ROADM technology.