“…They are generally used in various Planar Lightwave Circuit (PLC) applications, including power splitters, optical switches, and wavelength division multiplexers/demultiplexers. MMI couplers based on different materials, such as LiNBO 3 [4], SOI [5], InP [6], polymer [7], silica-on-silicon (SOS) [8], etc., have been reported. The versatility and efficiency of MMI couplers make them a crucial component in modern integrated photonics devices.…”