Design And Fabrication Of Delay Line Based On Wavelength Division Multiplexing Technology

With the rapid development of the communication technology nowadays,people have higher and higher requirements on the bandwidth and speed of communication network.The traditional phased array antenna,subjected to aperture effect and narrow bandwidth,cannot meet the increasing performance requirements.Then,thanks to the development of optoelectronic technology,optical phased array antenna which has advantages like large instantaneous bandwidth,no aperture effect,low loss,small size,and the resistance to electromagnetic interference has attracted the focus of many research institutions.The main technology of the optical phased array antenna technology is the optical true time delay technology,furthermore,the delay precision of the optical waveguide delay line which made by integrated optical process can up to picosecond scale,and it can meet the high requirements of radar frequency.Array waveguide grating(AWG)has played an important role in dense wavelength division multiplexing(DWDM)system,it has many advantages,such as flexible design,low insertion loss and low crosstalk,easy to coupled with fiber,the process is simple,easy to mass production,etc.In addition to the above advantages,polymer AWG has some other advantages,such as low cost,the refractive index is adjustable,easy to miniaturization,integration,as a result,the delay line based on array waveguide grating obtained the social focus.This paper focuses on the research of multi-channel polymer array waveguide grating and the folded wavelength selective delay line with single chip integrated with array waveguide grating.In this paper,the theory of optical waveguide and the basic theory of array waveguide grating are discussed.Through the study of the relationship between the structure parameters of the waveguide grating and the continuous optimization of the beam transmission algorithm,the small size and low crosstalk 64 channel polymer AWG has been designed.Then according to a series of experimental processes,such as film casting,vacuum coating,photolithography,reactive ion etching(RIE),and cutting grinding and polishing,a small size64 channel AWG chip has been realized.According to the final test results,we can know that the insertion loss of the chip is 18.75 dB,and the adjacent channel crosstalk @3dB is 18 dB,and the effective size of the chip is only 3.16 cm x 2.52 cm.Finally,we designed a delay line based on the array waveguide grating wavelength,inorder to verify the correctness of the design ideas,we first design a 8 channel folded AWG delay line,compared with traditional loopback AWG delay line,it has low crosstalk,and good uniformity.The time delay of different delay paths of this device is: 0ps,25 ps,50ps and75 ps respectively.Then,the 8-channel folded delay line device was developed successfully through the above experimental process.According to the final test results of the device,the related performance indexes of the 8-channel folded AWG are shown as follows: the insertion loss is 25dB;the loss uniformity is 2.3dB;The FSR is greater than 30dB;And the corresponding delay time measured is 0ps?24.3ps?50.2ps and 74.6ps respectively.According to the test data,the 8-channel folded AWG delay line is successfully verify the correctness of the design idea.