Passive Phase Shifters Based in 1×1 MMI for Cost-Effective Photonic Integrated Circuits

We propose a solution for fixed phase shifting in Photonic Integrated Circuits (PICs) based on 1x1 Multi-Mode Interference (MMI) with potential cost-effective production. Fixed phase shifting is essential in the design of a large number of building blocks in PIC. In many situations this is accomplished by using curved waveguides which can introduce unwanted complexity and are a source of power loss. Thus, the use of MMI structures is beneficial, especially in materials that are more sensitive to waveguide curvatures, such as Polymethyl Methacrylate (PMMA) and Di-ureasil–ZrOMc in which the refractive index contrast achieved is small. The developed devices in both materials were simulated, numerically characterized and their feasibility demonstrated. The proposed solutions to combine low cost with good performance and small footprint, which are important requirements for PIC design.