Coupling Length Analysis by Using Three Strips for Compact Design of Photonic Waveguide in Photonic Integrated Circuit

Development of compact photonic waveguide makes the possibility to design very dense photonic integrated circuits by using complex design structure. Conversely, compact photonic waveguide requires high coupling length between the neighboring photonic waveguides to avoid crosstalk between them. Some recent research demonstrated that to increase the coupling length between adjacent photonic waveguides, one can use the strips between them. In the current work, our focus is to obtain higher coupling length with reduced separation between the adjacent waveguides. By using three uniform silicon strips, the maximum coupling length of 3029 mu m has been achieved for the end-to-end separation between photonic waveguides of 300 nm. The obtained result is higher than previously reported values at the same separation of photonic waveguides. Higher coupling length is beneficial to design many compact photonic devices such as splitter, photonic switches, etc.