Dispersion of optical fiber (dispersion) refers to the time-diffusion phenomenon caused by the different wavelengths of light speed when the optical signal is transmitted in the fiber. Dispersion of optical fiber is related to the following factors:
1. Refractive index distribution of the fiber: the refractive index distribution of the fiber has a significant impact on the dispersion. Usually, the refractive index of an optical fiber is higher in the central axis and gradually decreases in the periphery. Different refractive index distributions result in different types of dispersion, such as waveguide dispersion and material dispersion.
2. Operating wavelength of optical fiber: the dispersion characteristics of optical fiber will change with the change of operating wavelength. Usually, optical fiber has a certain working wavelength range, in the range of dispersion is small. Beyond this range, the dispersion will increase significantly. For example, single-mode fibers have small dispersion in the communication wavelength range (typically 1310 nm and 1550 nm).
3. Refractive index of the fiber: The refractive index of the fiber also has an effect on the chromatic dispersion. There is a correlation between the refractive index and the speed at which the light signal travels through the fiber. When light signals of different wavelengths pass through an optical fiber, due to the difference in refractive index, their propagation speeds will be different, causing the phenomenon of chromatic dispersion.
4. Waveguide structure of the optical fiber: the waveguide structure of the optical fiber has a certain impact on the dispersion. Different types of optical fibers (such as single-mode fiber and multimode fiber) have different waveguide structures, resulting in different dispersion characteristics. For example, multimode fibers typically exhibit multimode dispersion (modal dispersion) due to transmission differences between modes.
5. Environmental conditions: The dispersion characteristics of optical fibers are also affected by environmental conditions. For example, temperature changes can cause the refractive index of the fiber material to change, which in turn affects dispersion. In addition, external factors such as stress and pressure may also cause changes in the dispersion of an optical fiber.
Understanding and controlling these factors is essential to optimize the dispersion characteristics of fiber optic transmission systems, especially in high-speed optical communications and fiber optic sensing applications.
