Multi-mode laser diodes (Broad-area laser diode) are light sources that provide high output power, reaching up to tens of watts. Multi-mode optical modules can only be used for short-distance transmission (SR) due to serious inter-mode dispersion; while single-mode optical modules are mostly used for long-distance transmission such as LR, ER, and ZR. Compared with a single mode laser, a multimode laser emits light in several transverse modes. As a result, the beam profile is broader and the. Multimode fibers are fibers having multiple guided modes at the operating wavelength — sometimes only a few (→ few-mode fibers), but often many.