Fiber structure
Fiber bare fiber is generally divided into three layers:
The first layer: a central high refractive index glass core (core diameter is generally 9-10 μm, (single mode) 50 or 62.5 (multimode).
The second layer: the middle is a low refractive index silica glass cladding (typically 125 μm in diameter).
The third layer: the outermost is a resin coating for reinforcement.
1) Core core: high refractive index, used to transmit light;
2) cladding coating: a lower refractive index, together with the core to form a total reflection condition;
3) Protective sleeve jacket: It has high strength and can withstand large impact and protect the optical fiber.
Fiber size
The outer diameter is generally 125um
Inner diameter: single mode 9um; multimode 50/62.5um
Numerical aperture
The light incident on the end face of the fiber cannot be transmitted entirely by the fiber, but only the incident light within a certain angle range. This angle is called the numerical aperture of the fiber. The larger numerical aperture of the fiber is advantageous for the docking of the fiber.