Design And Research Of Optical Communication Devices Based On The Band Gap And Defect Of Two Dimensional Photonic Crystals

With the rapid development of technology,especially the tremendous pressure brought by transmission speed and big data,electronic devices are gradually encountering performance bottlenecks.Compared with electronic devices,photonic devices have faster transmission speed,higher tolerance of fault and stronger anti-interference ability.Therefore,the using of photons instead of electrons to fabricate high-performance,and highly integrated photonic devices has become a hot research topic.The emergence of photonic crystals provides new ideas for modern high technologies such as all-optical communication and photonic integration.The photonic crystal filters,polarized beam splitters,all-optical switch and other devices have attracted wide attention due to their advantages such as small size,high transmission efficient,adjustable structure and so on.This thesis focuses on the two-dimensional photonic crystals with defects in the structure and launched depth study.The simulation work is carried out by RSoft optical simulation software.The main research contents of this thesis are as follows:1.Analyzed the photonic band gap and the transmission of several photonic crystal structures by plane wave expansion?PWE?method and finite-difference time-domain?FDTD?method.Choose the column triangular lattice photonic crystal,introduced three kinds of defects into the complete structure.The result shows that the point defect has a strong photonic locality,the line defect can transmit the waveguide well,and the transmission efficiency can be reach 88%at 120°;the ring defect can couple light waves.2.Designed a two-channel photonic crystal micro-cavity filter based on photonic band gap.The device introduces a centrally symmetric"L"type cavity in a two-dimensional triangular lattice photonic crystal.Introduces two points defects by changing the radius of the column.The simulation is carried out by using the finite difference time domain method and the plane wave expansion method.The result shows that the structure has 180°separation angle,the device size is only10?m?6?m,the transmittance of both 1550nm and 1110nm wavelengths can reach more than97%,the channel isolation is high and the device is easy to integrate.3.Designed a photonic crystal all-optical switch based on the ring resonator of photonic crystal and the nonlinear refraction effect.The ring resonator formed by the nonlinear refractive medium TiO₂,realized the switching on and off well.The simulation results show that,the output port has a transmittance of 99.4%and a response time of 14.3ps.This switch has good performance.4.Designed a photonic crystal polarizing beam splitter with a complete band gap of a honeycomb lattice photonic crystal.It mainly used the characteristics of TE mode and TM mode propagation in the complete band gap.By changing the radius of the column,the band gap of TE mode is shifted upwards,exceeding the complete band gap,achieved the purpose of separating two modes.The numerical calculation and simulation results of the polarizing beam splitter show that the designed structure can achieve high-efficiency separation of TE mode and TM mode.The transmittance near the 1550nm wavelength can reach over 98%,and the extinction ratio can reach19.01dB and 29.21dB.