（1）60 essential facts about optical fiber cables, save them and keep them with you!

1.Briefly describe the composition of optical fiber?

Answer: Optical fiber consists of two basic parts: the core and cladding, which are made of transparent optical material.

2. What are the basic parameters that describe the tranSMission characteristics of optical fiber lines?

Answer: Including loss, dispersion, bandwidth, cut-off wavelength, mode field diameter, etc.

3. What are the causes of optical fiber attenuation?

A: Fiber attenuation refers to the reduction of optical power between two cross sections of a fiber, which is related to wavelength. The main causes of attenuation are scattering, absorption, and optical loss caused by connectors and joints.

4.How is the optical fiber attenuation coefficient defined?

Answer: It is defined by the attenuation per unit length of a uniform optical fiber in steady state (dB/km).

5.What is insertion loss?

Answer: It refers to the attenuation caused by inserting optical components (such as inserting connectors or Couplers) into the optical transmission line.

6.What does the bandwidth of optical fiber depend on?

A: The bandwidth of an optical fiber refers to the modulation frequency when the amplitude of the optical power is reduced by 50% or 3dB compared to the amplitude of the zero frequency in the transfer function of the optical fiber. The bandwidth of an optical fiber is approximately inversely proportional to its length, and the product of the bandwidth and length is a constant.

7.How many types of dispersion are there in optical fibers? What are they related to?

Answer: Fiber dispersion refers to the broadening of the group delay within a fiber, including modal dispersion, material dispersion and structural dispersion. It depends on the characteristics of both the light source and the fiber.

8.How to describe the dispersion characteristics of signals propagating in optical fibers?

Answer: It can be described by three physical quantities: pulse broadening, fiber bandwidth, and fiber dispersion coefficient.

9.What is the cut-off wavelength?

A: It refers to the shortest wavelength that can only transmit the fundamental mode in the optical fiber. For single-mode optical fiber, its cut-off wavelength must be shorter than the wavelength of the transmitted light.

10.What impact does optical fiber dispersion have on the performance of optical fiber coMMunication systems?

Answer: The dispersion of optical fiber will cause the optical pulse to be broadened during transmission in the optical fiber, affecting the bit error rate, the transmission distance, and the system rate.

The phenomenon of optical pulse broadening in optical fiber caused by the different group velocities of different wavelengths in the spectral components of the light source.