The Research Of Cascaded Y-branch Optical Waveguide Fabricated By Ion-exchange In Glass

Along with the unceasing development of Optical Network and Communication techniques, integrated optical devices has been more and more widely used. In many materials glass has extremely low propagation loss and is easy to process which makes it possible to integrate optical waveguide in glass substrate. Ion exchange can be used to fabricate low-cost optical waveguides in glass. And the waveguide mode can match with conventional SMF very well. The ion exchange process is simple and suitable for large volume batch processing without expensive facilities. In addition, ion exchange process offers considerable flexibility in the choice of fabrication parameters and, therefore, can be optimized for a wide variety of applications. More and more attention has been focused on it.In this paper we firstly introduced the application of integrated optical devices in glass, fabrication techniques and the present situation of ion exchange used in making glass waveguides. We also surveyed in the development of passive optical power splitter.Secondly we launched researches in characteristics of ion exchanged glass waveguide and the correlative process. We discussed about the sources of waveguide losses, ways to improve the output performance, the principle of ion exchange as well as choices of salts and facilities. Then we got a series of process controlling parameters.High modes can be easily induced by the asymmetry of input field. It will degrade the uniformity of the waveguide. Besides, the interference effect between radiation field and fundamental mode also has negative influence on the output performance. Based on researches above, we proposed a novel structure of Y-branch waveguide which is suitable for cascaded power splitter. The new structure can improve the uniformity of the device by filtering out the high modes. The uniformity of 0.0191dB and 0.0214dB can be respectively achieved with narrow waveguide in1x4 beam splitter under the input wavelength of 1.3um and 1.55um. And it has little influence on the size and excess loss of the device.After that we designed a series of 1 xN optical power splitter (1x4, 1x8, 1x16, 1x32) with further improved structure to upgrade the integration level of the devices. Through two-step field-assisted ion exchange we made out the buried splitters.Take 1x8 for example, the insertion loss is lower than 11.137dB and the uniformity is more excellent than 0.40 ldB. From the performance of the devices we can see the reasonability of the waveguides' structures and controlling parameters of ion-exchange process.