Research On Variable Optical Delay Technology Of Integrated Optics

Optical delay line is an important device in the field of optical communication and has important applications in the true delay of phased array antenna.Compared with optical fiber delay lines,integrated optical waveguide delay lines have the advantages of high accuracy,low loss,and small size.In view of the difficulty of continuous delay tuning and large delay bandwidth at the same time,a broadband continuously tunable integrated optical waveguide delay line is proposed in this thesis.The main research contents are as follows:(1)A design scheme of broadband continuous tunable optical delay line is presented.By studying the basic theory of integrated optical waveguide,including the analysis method of optical waveguide,coupler,optical switch,microring resonator and the basic principle of thermo optical effect and heat conduction for tuning optical switching state,the anti-resonant microring and N bit switching delay line are proposed to be deployed on silicon waveguide on insulating substrate.The delay line not only realizes the continuous delay tuning of the range 0～2~NΔτ,but also has the characteristics of flat delay and large bandwidth.The structure of the integrated optical delay line is designed,and the delay ripple and delay step analysis are carried out for the core device tunable coupling microring which affects the optical delay line bandwidth and delay continuous tuning performance.The data reference and theoretical support are provided for the integrated simulation design of the delay line.(2)The key components of integrated optical delay line are simulated and optimized.Firstly,the refractive index distribution and the mode field distribution of light in the single mode waveguide are analyzed.Secondly,the influence of the cladding thickness of the waveguide and the position and size of the air groove on the steady-state and transient performance of the thermo-optical phase shifter is analyzed by thermal simulation.The optimization of the heating resistance power of the thermo-optical phase shifter is achieved,which is 49.7%,and the rise and fall time is 46.6%.The transverse and longitudinal thermal crosstalk analysis is carried out.The bandwidth and splitting ratio of the multimode interferometric coupler and the loss of the curved waveguide are then optimized by scanning the device size parameters and optical wavelength.The simulation results show that the extinction ratio of the optical switch is 35.6 d B,the switching power consumption is about 9.4 m W,the switching time is about 35.55μs,the loss is less than 2.75 d B in the wavelength range of 1500 nm to 1600 nm,and the crosstalk between the channels is less than-31.72 d B.Finally,the structure simulation design of the tunable coupling microring is carried out,so that the delay range covers 0～10 ps,and the anti-resonant wavelength is stable at 1550 nm.(3)The performance analysis and application research of broadband continuously tunable integrated optical delay line are presented.Firstly,the performance of the integrated optical delay line composed of microring and 4-bit switched delay line is analyzed.The delay range of the optical delay line can cover 0～160 ps,and the loss is less than 3.21 d B.The delay ripple is less than 1.6 ps and the loss ripple is less than 0.03d B within 20 GHz near 1550 nm.Then,the delay line is applied to an 4-element optically controlled phased array antenna for X band.The beam scanning range from-45°to+45°can be achieved,the beam skew is less than 2.69°within 20 GHz bandwidth,and the beam scanning angular resolution is less than 0.23°.It shows the application value of the broadband continuously tunable integrated optical delay line.