Study On Optical Devices Based On Integrated Optical Waveguide

With the development of integrated optics,more and more devices are integrated into optical chips.On the one hand,in order to achieve high integration and high stability of three-dimensional optical chips,it is necessary to systematically study the coupling characteristics of three-dimensional space optical waveguides.For this research,the coupling between waveguides in three-dimensional integrated optical chip is systematically studied in this paper.On the other hand,in integrated optical waveguide chips,the birefringence of optical waveguide leads to the degradation of the overall performance of integrated devices.As one of the main components of polarization diversity system,polarization rotator can greatly reduce polarization dependent loss and polarization mode dispersion.For this research,the polarization rotator based on adiabatic waveguide is proposed,which shows good performance in cross-polarization conversion efficiency and polarization extinction ratio.This paper first summarizes the concepts of optical communication and integrated optics and introduces the key components of integrated optics.The second chapter mainly summarizes the optical waveguide theory,including the optical frequency Maxwell equation,boundary conditions,Helmholtz equation,optical waveguide mode,analysis methods of optical waveguide theory,optical waveguide coupling mode theory and several commonly used numerical analysis methods,and expounds the optical waveguide fabrication process.In third chapter,the coupling between waveguides in three-dimensional integrated optical chips is systematically studied.Firstly,the coupling characteristics between parallel waveguides are studied,and the effects of waveguide spacing,refractive index of surrounding medium and working wavelength on the coupling efficiency between waveguides are analyzed.Then,the coupling characteristics between spatial crossing waveguides are studied,and the effects of angle between waveguides on the coupling efficiency are analyzed.The finite difference time domain method(FDTD)and eigenmode expansion method(EME)are used for numerical simulation.The results show that the structure,position and working wavelength of waveguides have important effects on the coupling efficiency.The results can provide theoretical guidance for optical path design on integrated optical chip.In fourth chapter,a polarization rotator based on adiabatic waveguide is proposed,which is composed of a strip Si waveguide with twisted angle.The finite difference time domain method(FDTD)are used for numerical simulation.The results show that the polarization rotator has the characteristics of small footprint,high polarization extinction ratio and high cross-polarization conversion efficiency.At 1.55μm wavelength,the cross-polarization conversion efficiency of the rotator is up to 0.996,and polarization extinction ratio is up to 35.03 d B.The 20 d B working bandwidth of the device is about 210 nm.