Optical fiber splitter is a device used to split and combine light wave energy. It distributes the light energy transmitted in one optical fiber to two or more optical fibers according to a predetermined ratio, or combines the light energy transmitted in multiple optical fibers into one optical fiber. The optical splitter can be divided into two types according to the principle: fusion taper type and planar waveguide type. The fusion taper type product is formed by fusing two or more optical fibers on the side; the planar waveguide type is a micro-optical component type product. Photolithography technology, forming an optical waveguide on a medium or semiconductor substrate to realize the branch distribution function. The two types of optical splitting principles are similar. They achieve different branch amounts by changing the evanescent field coupling between the fibers (coupling degree, coupling length) and changing the fiber radius. Conversely, multiple optical signals can be combined into one signal. It's called a synthesizer. Because of its simple manufacturing method, low price, easy connection with external optical fiber, and resistance to mechanical vibration and temperature changes, the fusion-tapered optical fiber coupler has become the mainstream manufacturing technology in the market.