Design And Simulation Of The Flat-field Output Of Etched Diffraction Grating Wavelength Division Multiplexing And Device Fabrication

The optical communication is developing at very fast speed these years. Wavelength Division Multiplexing (WDM) is an effective technique to meet the fast-grown demand for communication capacity. Dense Wavelength Division Multiplexing (DWDM) has been successfully put into commercial use. DWDM's ability of expanding the communication capacity is in continuous growth. As the key device of a DWDM system,Etching Diffraction Grating (EDO) is one of the most potential types of planar waveguide DWDM devices.In this paper a brief introduction of EDO is presented,the design of the EDO parameters is analyzed and a set of typical designed parameter is described. Then,the Kirchhoff scalar diffraction theory is used to derive the scatter field of the EDO grating and the simulation model is presented. Using this model the basic demultiplexing characteristics of EDO are obtained. The results include the intensity distribution along output,spectral response,dispersion,etc. Based on this,the design of Flat Input/Output is put forward. A conventional EDG design is based on the Rowland circle on which the end points of the input and output waveguides located. An EDG with flat input/output has many advantages. For example,in some applications an EDG without input and output waveguides is preferable and it is much easier to fabricate. An EDG of flat input/outputs can also maintain a good linear dispersion and a perfect focused field as a conventional EDG This paper presents a design method for an EDG of flat input/outputs is presented. The scalar diffraction theory is used to verify the design and the numerical results show that the designed EDG has a good performance. Besides the scalar diffraction theory,the simulation method of Beam Propagation Method,which is extensively used in the simulation of integrated optical devices,is also discussed though no successful result of calculation with BPM is given.The key point of the fabrication of integrated optical devices is to prepare the planar waveguide structure with high quality. Silica (SiO2) is a very promising material used to fabricate the optical waveguide for its low insertion loss,efficient fiber-to-chip coupling,high integration density and compatibility with microelectronic process. It is possible to realize the monolithic integration of optical devices with microelectronic devices and the passive devices with the active ones. Without using the doping of Ge,Plasma Enhanced Chemical Vapor Deposition (PECVD) of thick silica films on Si substrates with gas mixtures of SiH4 and N2O has been investigated. Various factors affecting the refractive index and the deposition rate of the deposited films are studied to optimize growth conditions of the films. The microstructures and optical properties of the films are characterized by a prism coupler,a Fourier transform infrared spectroscopy (FTIR) and an Atom Force Microscopy (AFM). Also,the effect of the annealing to the films is discussed. The results showed that thick films with a uniform surface and small loss for infrared light can be rapidly deposited by the PECVD technology and the refractive index of the films can be controlled accurately. After annealing,the refractive index of the film decreases. And,the annealing process release the stress of the films,which give the film a higher density. When the two layers of SiO2 with different refractive index are finished,the designed mask pattern is printed on the film by photolithography. After that,ICP is performed for dry etching,then,the waveguide structures are obtained. At present,the rudimental graph of EDG has been obtained.