1. Describe the components of the optical fiber.

A: An optical fiber consists of two basic parts: a core made of transparent optical materials and a cladding layer and a coating layer.

2. What are the basic parameters for describing the transmission characteristics of an optical fiber?

A: 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 decrease in optical power between the two cross sections of an fiber and is wavelength dependent. The main causes of attenuation are scattering, absorption and optical loss due to connectors and joints.

4. How is the optical fiber attenuation coefficient defined?

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

5. What is insertion loss?

A: Refers to the attenuation caused by the insertion of optical components (such as connectors or couplers) in the optical transmission line.

6. What is the bandwidth of the optical fiber related to?

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

7. How many kinds of dispersion do optical fibers have? With what?

A: The dispersion of optical fiber refers to the broadening of the internal group delay of an optical fiber, including mode dispersion, material dispersion and structural dispersion. Depends on the characteristics of both the light source and the fiber.

8. How to describe the dispersion characteristics of signal propagation in optical fiber?

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

9. What is the cut-off wavelength?

A: refers to the optical fiber can only conduct the fundamental mode of the shortest wavelength. For single-mode fibers, the cut-off wavelength must be shorter than the wavelength of the transmitted light.

10. What is the effect of optical fiber dispersion on the performance of optical fiber communication system?

A: The dispersion of the fiber will widen the optical pulse as it travels through the fiber. It affects the size of the bit error rate, the length of the transmission distance, and the size of the system speed.

The broadening of optical pulses in an optical fiber caused by different group velocities of different wavelengths in the spectral component of the source.