The structure of the optical fiber is drawn from a prefabricated silica fiber rod. The outer diameters of the multi-mode fiber and single-mode fiber for communication are both 125 μm. The body is divided into two areas: Core and Cladding layer. The core diameter of single-mode fiber is 8~10μm, and the core diameter of multimode fiber has two standard specifications, the core diameters are 62.5μm (American standard) and 50μm (European standard).
The interface fiber specification has this description: 62.5μm/125μm multimode fiber, where 62.5μm refers to the core diameter of the fiber, and 125μm refers to the outer diameter of the fiber. The wavelength of light used by single-mode fiber is 1310nm or 1550nm. The light wavelength used by multimode fiber is mostly 850 nm. Single-mode fiber and multi-mode fiber can be distinguished from the color. The outer body of single-mode fiber is yellow, and the outer body of multi-mode fiber is orange-red. Gigabit optical port auto-negotiation Gigabit optical port can work in two modes: mandatory and auto-negotiation. In the 802.3 specification, a gigabit optical port only supports a rate of 1000M, and supports two duplex modes, full-duplex (Full) and half-duplex (Half). The most fundamental difference between auto-negotiation and mandatory is that the code streams sent when the physical link is established are different. The auto-negotiation mode sends the /C/ code, which is the configuration code stream, while the mandatory mode sends / I/code, that is, idle code stream. Gigabit optical port auto-negotiation process