Performance Analysis Of Multi-channel Wavelength-Mode Division Hybrid Multiplexer/Demultiplexer

With the rapid development of Internet technology,distance education,medical treatment,cloud computing,and big data,the transmission capacity of optical fiber communication system needs to be greatly increased.Optical fiber communication system is developing from multi-channel,high-rate to ultra-high rate,super-capacity and ultra-long distance.In order to meet the demand,multiple multiplexing technologies are used to increase the communication capacity,but the single multiplexing technology has limited improvement in the capacity of the optical communication system.Combing wavelength division multiplexing technology with mode division multiplexing technology can increase system capacity and spectrum effifiency exponentially,which can be applied as the most effective method to multiply communication capacity.The wavelength-mode division hybrid multiplexer/demultiplexer is a key device in the wavelength-mode division multiplexing system.It is of great application value to study wavelength-mode division hybrid multiplexer/demultiplexer with excellent performance.This thesis proposes a 6-channel wavelength-mode division hybrid multiplexer/demultiplexer based on photonic crystals.The device consists of three combined resonators,three wavelength selective reflection microcavities,single mode waveguides,multimode waveguides and tapered coupled waveguides.The filtering is realized by the structure of combined resonator and wavelength selective reflection microcavity,and the mode conversion is realized by the structure of the asymmetric parallel waveguide.Two kinds of models are established.The coupled-mode theory is used to analyze and the finite difference time domain method is used to simulate.The simulation analysis by finite difference time domian method shows that the device can realize the multiplexing/demultiplexing of six channels,i.e.,the 1550 nm TM₀ mode,1530 nm TM₀ mode,1550 nm TM₁ mode,1530 nm TM₁ mode,1550 nm TM₂ mode and 1530 nm TM₂ mode.Its insertion loss is<0.46d B and the channel crosstalk is<-15.28d B.Then,in order to reduce the wavelength interval,the wavelength division module is replaced by a bichromatic cavity.A6-channel hybrid multiplexer/demultiplexer with working wavelengths of 1563.2nm and 1558.2nm and working modes of TM₀ mode,TM₁ mode and TM₂ mode is proposed to reduce the wavelength interval of the device to 5nm.Its insertion loss is<0.86d B and the channel crosstalk is<-11.07d B.These two devices have important practical value for the wavelength-mode division multiplexing system.