How do you think of fiber single-mode and dual-mode?

　　To distinguish whether the fiber is single-mode or dual-mode (commonly referred to as "dual-mode" fiber actually refers to multi-mode fiber), the following methods can be used:

　　First, color distinction

　　Single-mode fiber: usually indicated in yellow, with its connector and protective sleeve in blue.

　　Multimode fiber: usually indicated in orange or gray, while connectors and protective covers are beige or black.

　　Second, model distinction

　　Single-mode fiber: Common models include GYTS and GYXTW.

　　Multimode fiber: Common models include GYFTZY and GYFTY.

　　III. Identification

　　Single-mode fiber: usually marked with "SM".

　　Multimode fiber: usually marked with "MM".

　　Fourth, the appearance and size distinction

　　Single-mode fiber: The appearance is relatively thin, with a core diameter of 9 or 10 micrometers and a size of 0.9mm or less.

　　Multimode fiber: relatively thick in appearance, capable of transmitting multiple modes of fiber, usually 2.5mm or larger in size.

　　V. Transmission performance differentiation

　　Single-mode fiber: Only one mode of fiber can be transmitted, with a long transmission distance, typically up to several kilometers, suitable for long-distance communication.

　　Multimode optical fiber: capable of transmitting multiple modes of optical fiber, with a short transmission distance, typically around hundreds of meters, suitable for medium and short-distance and small-capacity optical fiber communication systems.

　　Six, the light source distinction

　　Single-mode fiber: Lasers are usually used as light sources.

　　Multimode fiber: A variety of light sources such as laser diodes and LEDs can be used.

　　VII. Cross-sectional observation

　　Single-mode fiber: There is only one optical core in cross-section.

　　Multimode fiber: There are multiple optical cores in the cross section (although in practical applications, we usually do not distinguish between single-mode and multimode fibers by directly observing the cross section, because this requires high-precision equipment and technology).

　　In summary, it is possible to distinguish whether a fiber is single-mode or multi-mode by various methods such as color, model, logo, appearance and size, transmission performance, light source, and cross-sectional observation (although not commonly used). In practice, the appropriate method can be selected according to specific needs and conditions to distinguish.