Trimming of InP-based Mach-Zehnder interferometer by filling side cladding of high-mesa waveguide with resin

A trimming method for an InP-based Mach-Zehnder interferometer (MZI) is proposed and demonstrated by filling the side cladding of a high-mesa waveguide with resin. The trimming structures have trimming grooves that are separated by polyimide to obtain a stable and easy phase shift. After investigating the amount of phase shift realised by filling one groove with resin, a trimming operation designed to match the characteristics of four MZIs is described.