Ion-Exchange Technique For Directional Couplers Fabrication On Glass Substrate

A more economical directional couplers (DC) fabrication method based on ion exchange Ag+/K+ /Na+ technique at the temperature of 300°C was studied here. Beam propagation method (BPM) had been employed to study the light-coupling phenomenon in a directional coupler. It was found that light coupling was critically influenced by the separation (d) between two waveguides. It showed that coupling could be achieved faster when wavelength (A.) to waveguide separation distance (d), Nd is greater than 1.5. The time required for ion-exchange process was a crucial factor to control the ratio of output powers at the two output ports. From the Ion-exchange fabrication technique, it was found that side diffusion was an important consideration for mask design. It could be concluded that as far as the device geometry is still in single-mode regime, this ion-exchange fabrication method eliminates the need/or high-resolution lithography for producing exact geometry of the device, thus making the process a very economical one