Design And Simulation Of AWG Based On Si-wire Waveguide

Internet's requirement for network band width which grows day by day has created a fast growing market for the Wavelength Division Multiplexing components and the system.Many different technologies and techniques can be used to realize the Wavelength Division Multiplexing/Demultiplexing(MUX/DMUX)components, compared with other types of MUX/DMUX,Arrayed Waveguide Grating(AWG)has the merits of low insertion loss,low crosstalk,high reliability,low processing request and small size.But AWG based on Planar Lightwave Circuit technology is the core device for constructing the ultra large capacity Wavelength Division Multiplexing system.And it has become an important research area of fiber optic communications technology in recent years.In order to meet optical network system's requirement for economy and versatile optical devices in the future,the size reduction of types of function optical devices and theirs integration has become the key.Compared to the general size components,the function loss of this component will be reduced with the reduction of optical devices.To further enhance the integration and running rate of the chip,the existing bulk-silicon material and techniques are approaching their physical limit,and face to stem challenge in the aspect of future characteristic size reduction of integrated circuits,so there should be new important breakthrough in the material and techniques.At present Silicon on Insulator which is impelled in the aspect of material are recognized as one of solutions to replace the existing monocrystalline silicon material in the nanometer technology era.Silicon wire waveguide which takes SOl material as the substrate utilizes the total internal reflection principle to concentrate lightwave energy in the band of high refractive index so as to realize the guided waves function,therefore the size of the core can be smaller than 1 um,and the bend radius can reach several micrometer.In the article,the design of AWG is based on silicon wire waveguide,the structure consists of a silicon core,SiO₂ and silica-based cladding that have refractive indices of 3.46,1.45 and 1.5,respectively,yielding a refractive index contrast as high asΔ＞40%,so the bend radius of the light waveguide can be very small.In order to provide singie-mode propagation at communication wavelength aroundλ=1550 nm,the thickness of Si core is 0.32 um and its width is 0.45 um,the thickness of SiO₂ is 1 um.Using APSS software combined with the finite difference method to compute and simulate,the simulation result indicates that the bend loss is smaller than 0.001 dB when the bend radius of the waveguide is 2 mm.In our design,bend radius of all wave guide should be bigger than 2mm.In the process of designing AWG,tapered waveguide is used to reduce its insertion loss.Take 1550 nm wavelength as the example,from the simulation data we can know, the minimum insertion loss of AWG without tapered waveguides is -6.208 dB while the insertion loss of AWG with tapered waveguides reducing to -1.565 dB,so the insertion loss is improved obviously.Using this simple and effective method,we can utilize tapered waveguides between planar waveguide and input/output waveguide to reduce radiation of guided mode optical field,without increasing manufacture difficulty of the component and can reduce the insertion loss of AWG greatly.1550/1625 nm wavelength MUX is usually used in the Optical Fiber Cable Automatic Monitoring System.We design a 1×2 AWG based on Si-wire waveguide,the clear DUX characteristics are observed with the insertion loss -1.157dB,-1.277dB and the cross talk loss 35dB,43dB at the wavelength of 1550,1625nm respectively.The size of the AWG is 117×217um²,which is far smaller than the present mature silicon-based SiO₂ AWG.It can make the 1550/1625nm wavelength MUX used in Optical Fiber Cable Automatic Monitoring System in the future highly integrated,through optimizing waveguide distribution structure et al.,the designed AWG can be made more compact.Finally,related research works in the thesis are briefly concluded and the future related works are preliminary forecast.