Mode Field Adapter (MFA)

A Mode Field Adapter (MFA) is a passive fiber-optic component designed to connect two fibers with different mode field diameters (MFDs) and optical characteristics, such as numerical aperture (NA), core diameter, or refractive-index profile. It is widely used in fiber amplifiers and fiber laser systems. An MFA typically employs an adiabatic tapered transition to gradually match the optical mode fields of the two fibers, thereby minimizing splice loss, suppressing higher-order mode excitation, and enabling efficient fundamental-mode coupling and transmission. We offer MFAs for various operating wavelengths, fiber types, power levels, and package configurations to meet diverse application requirements. For directional identification, we define transmission from the fiber with the smaller MFD to the fiber with the larger MFD as the forward direction, and transmission from the larger-MFD fiber to the smaller-MFD fiber as the backward direction.