A Study On Glass Based Spot Size Converters

Due to the huge mode field mismatch between the optical fiber and the SOI(Silicon-on-insulator)waveguide,the loss when the two are directly edge coupled is very high.Spot size converters(SSC)are used to reduce the mode field mismatch,thereby reducing the edge coupling loss.So far,researchers have proposed siliconbased SSC of various structures,including: three-dimensional SSC,double-layer SSC,inverse taper based SSC and gradient-index(GRIN)lens based SSC,etc.In addition,there are some studies on ion exchange glass-based spot size converters.The glass-based SSC is made of glass-based ion exchange optical waveguide technology,which has the unique advantages of simple process and low cost.This paper studies the glass-based SSC,the main contents are as follows:1.Simulation of the glass-based ion exchange processes: Starting from the general diffusion equation,the Finite Difference Time Domain Method(FDTD)was used to simulate the thermal ion exchange,reverse exchange and electric field assisted ion migration processes to get the waveguide ion concentration distribution and refractive index distribution,and RSoft was used to simulate the influence of ion exchange window width and diffusion depth on the waveguide mode field size.2.Design,preparation and characterization of glass-based surface SSC: Different sizes of glass-based surface SSC were designed and prepared through glass-based ion exchange optical waveguide technology.The test results show that the mode conversion loss introduced by the glass-based surface SSC is below 1.0d B.3.Improvement of glass-based SSC: A glass-based segmented spot size converter was proposed.By cascading multi-segment glass-based tapered waveguide chips,it is possible to achieve a greater reduction of the spot size.