The Basic Research On Fabricating Arrayed Waveguides Grating By UV-writing

With the rapid increase of global message volume, optical communicationsystem,s demand for bandwidth and capacity improves constantly, wavelengthdivision multiplex system is capable of realizing high-capacity and multifunction.so it has great application potential in network service and becomes preferredtechnology in optical fiber communication field. Arrayed waveguide grating isconsidered as a kind of new promising device due to its low propagation loss,high wavelength resolution, easily coupled with optical fiber. It consists ofinput/output waveguides, two focusing slab regions and a phase-array of multiplechannel waveguides with the constant path length difference ?L betweenneighboring waveguides. In this paper we first introduced the progress of arrayed waveguide grating andits applications in optical communication field, such as optical beamsplitter/router, wavelength option switch, optical add/drop multiplexer andmultifrequency laser. This fully shows that arrayed waveguide grating is mostpromising. Then we introduced the basic structure and function of arrayed waveguidegrating, and briefly deduced the optical waveguide principle of arrayedwaveguide grating, explained the usual methods of the phase error compensationand temperature error compensation and flat spectral response and briefringencecontrolofAWG. Silica-on-silicon planar waveguide technology has developed since 90′ｓ,which is very mature at abroad and turns into people,s research hot topic at home.More and more attention has been paid to silica waveguide on silicon because ofmature silicon processing technic , easy photoelectronic device,s integration on a 67large scale and optical fiber guide-wave material silica,s convenient fabrication onsilicon substrate. The preparation of silica-on-silicon waveguide materials isalways one of the hard and key steps to fabricate AWG devices. 　 In this paper, silica films and silica doped germanium dioxide films werefabricated by flame hydrolysis deposition. This method is widely used owing toits quick film forming speed, simple equipment, easy operation. We have prepareduniform and low loss silica films and silica doped germanium dioxide films bythis method, and the films were consolidated in electric furnace and vacuum furnace,which makes the films more compact and makes their absorption loss lower.Afterwards, we measured and analyzed the surface characteristics of the silicafilms before and after annealing by SEM, AFM, XRD, XPS and VASE .FromXPS ,We can know that Si-O configuration is chemical matching, but matching ofO becomes bigger because oxygen was absorbed in the surface during theannealing, so it is necessary to anneal in vacuum. According to AFM and SEM,silica films after annealing is very compact and can reduce the scattering losseffectively. At the same time, we surveyed the refractive index and extinctionindex of silica films, the refractive index is 1.4564 and loss is 0.1dB/cm at1.55μm, it is fit for the under-cladding; then we tested and analysed andcompared films,characteristics before and after annealing in electric furnace (airambience) and vacuum furnace (vacuum ambience), we found that the ambience ofannealing can affect the state of consolidated SiO2 films: the films are amorphousflocculent structrue before consolidating; the films are tight crystal SiO2(crystobalite) after consolidating in electric furnace; however, the films are compactand uniform, smooth and transparent vitreous state after consolidating in vacuumfurnace.And the thickness of the films after consolidating turns thinner. 68In recent years, more and more attention is paid to the refractive changeinduced by UV-writing in GeO2-SiO2 films because it can be used in integratedlightwave circuits and integrated optical components. The photosensitivity isfound near the 5eV absorption band, its immediate result is...