Design And Fabrication Of Multi-channel Polymer Array Waveguide Grating

Due to the surge in communication capacity of modern society,it is urgent to improve the capacity and speed of communication network.Dense wavelength division multiplexing(DWDM)technology can solve the above problems effectively.Arrayed waveguide grating(AWG)has a very important role in DWDM system.It is based on Planar Lightwave Circuit(PLC).It has the advantages of flexible design,low insertion loss,low crosstalk,coupling with fiber easily,simple process and suitable for large-scale production and so on.The polymer AWG stands out from the PLCs because of the advantages such as low cost,easy adjustment of refractive index,easy to miniaturization and integration,etc.AWG devices are also easier to integrate with the other passive or active devices to achieve a variety of functions,so that it becomes the research focus in applications and development of the optical communication networks.The purpose of this paper is to develop a multi-channel polymer array waveguide grating with excellent performance.In this paper,the optical waveguide theory and the basic theory of arrayed waveguide grating were introduced firstly.By studying the interaction between AWG structural parameters and performance indexes,the 23-channel AWG was designed,simulated and optimized by Beam Propagation Method(BPM).Then,the preparation technology of polymer AWG was studied,especially the etching process,and the optimum etching parameters were obtained.The optimum etching parameters of Reactive Ion Etching(RIE)were as follows:the etching power was 100 w,the pressure in the reaction chamber was 3 pa,the etching gas was O2:CHF3 = 30:20,the etching rate was about 0.1 ?m/min;the optimum etching condition of Inductively Coupled Plasma(ICP)etching was RF power of 50 w,ring power of 0 w,chamber pressure of 0.5 pa,gas ratio of O2:CHF3 = 30:20,etching rate of about 0.1216 ?m/min.It was found that the etching effect of RIE was more ideal.Then,23-channel AWG chips with a channel spacing of 50 GHz were fabricated successfully by the experiment,including spin coating,vacuum coating,photolithography,etching by RIE,cutting,grinding and polishing etc.The test results show that the insertion loss of the chip was 22.46?26.12 dB,the adjacent channel crosstalk was 8?10 dB,the insertion loss uniformity was about 3.66 dB,and the effective size of the chip was 3.40× 3.75 cm2.In order to reduce the size and improve the performance of the device,two optimization designs were proposed.One was to optimize the AWG structure parameters,especially for several important parameters and bending radius.The effective size of the chip was reduced to 2.78 x 3.07 cm2,the length and width were both reduced by about 0.7 cm.The other was to increase the refractive index difference of the core layer and the cladding layer of the material to further reduce the size,which reduced the size of chip to 1.45 x 1.97 cm2 in simulation,the length and width were reduced by 1.33 cm and 1.10 cm respectively.The test results showed that the insertion loss of the optimized small size AWG chip was reduced by 7?8 dB,the adjacent channel crosstalk was reduced by about 5 dB,the insertion loss uniformity was reduced by 1 dB.The experimental results not only achieved the compact of AWG,but also enhanced the performance of the device greatly,while indicated that it could achieve the miniaturization of the device with the similar performance by improving the refractive index difference,which had laid a good foundation for future integration of the optical waveguide devices.