Design and Fabrication of MMI Optical Coupler Using Ti-diffused Lithium Niobate Waveguides

Optical couplers based on Multi-mode interference (MMI) were considered using Ti-diffused LiNbO
₃
(Ti:LN) waveguides. Properties of MMI waveguides of Ti:LN were analyzed using the beam propagation method. An optical 90-degree hybrid of the MMI structure was designed and fabricated with the Ti:LN waveguides. We experimentally confirmed that the MMI coupler could operate as a 90-degree hybrid using the MMI waveguide part of 50 μm width and 2.13 mm length.