Modal noise in single-mode fiber-optic systems with closely spaced splices

Modal noise can be a problem in single-mode fiber-optic systems when short lengths of fiber are spliced into the system. Previous analyses have dealt only with lengths greater than 1 m. With very short lengths (< < 1 m), noise is not a problem, but modal interference can still manifest itself in the form of a time-invariant attenuation. Modal interference must be considered in the design of components that utilize very short pieces of fiber.