What is the structure of the fiber composition, what are the parameters?

What is the structure of the fiber composition, what are the parameters? 1 what are the basic parameters analysis the transmission properties of optical fiber? A: the main is loss, dispersion, bandwidth, cutoff wavelength, mode field diameter, and so on. 2. Introduced the structure of the fiber answer: two basic parts: the optical fiber is mainly made of transparent optical material fiber core and cladding, the cladding layer. 3. Can produce optical fiber attenuation are the reasons? Answer: the attenuation of the fiber is to point to in a single fiber optical power between the two cross section reduction, this related to the wavelength. Is the main reason of the attenuation caused by scattering and absorption and optical loss due to connector, connector. 4. Optical fiber attenuation coefficient is how to determine? A: with steady state in a uniform fiber attenuation (per unit length dB /公里) To judge. 5. The bandwidth of the fiber and what department? Answer: the bandwidth of the fiber refers to: in the transfer function of the fiber, the optical power amplitude of 50% lower than zero frequency amplitude modulation frequency or 3 db. The bandwidth of the fiber approximation is inversely proportional to its length, the length of the bandwidth of the product is a constant. 6. What is the insertion loss? A: refers to insert the optical components in optical transmission line will cause attenuation. 7. The dispersion of the fiber has several? And what about? Answer: the dispersion of the fiber is to point to a single fiber within the group delay spread, including mode dispersion, the structure of the material dispersion and dispersion. Depending on the light source, optical properties of both. 8. The solving of dispersion characteristics of signal transmission in optical fiber how to describe? Answer: can use the pulse broadening, the bandwidth of the optical fiber, optical fiber dispersion coefficient to describe the three physical quantities. 9. What is the cutoff wavelength? A: refers to the optical fiber only conduction base model of the shortest wavelength. For single mode fiber, the cutoff wavelength must be shorter than the wavelength of light transmission. 10. The dispersion of the fiber on the performance of optical fiber communication system will produce what kind of impact? Answer: the dispersion of the fiber will make the broadening of optical pulses in the optical fiber transmission. Affect the size of the bit error rate, and the length of the transmission distance, and the size of the system speed. 11. What is the backscatter method? Answer: the backscatter method is a kind of measurement method of attenuation along the fiber length. For the most part of fiber optical power for the former to spread, but there are very few to shine through to scattering. In the light emitting device using the beam splitter observed backscatter time curve, from one end can not only measure the length of the uniform access of optical fiber and attenuation, and measure the irregularity of local, breakpoints, and in the light of connectors and connector power loss. 12. Optical time domain reflectometer ( OTDR） The test principle of is what? What is the function? Answer: OTDR based on the backscattering light and Fresnel reflection principle, when the use of light propagation in optical fiber attenuation of backscatter light to get information, can be used for measuring optical attenuation, splicing loss, fiber optic fault point positioning and understand the status of loss distribution along the length of optical fiber, etc. , is an essential part of fiber optic cable construction, maintenance and monitoring tools. The main parameters including: dynamic range, sensitivity, resolution and measuring time and blind area, etc. 13. OTDR blind area how to judge? Have any influence on test? In the practical test of blind area? A: usually will such as dynamic reflection feature points such as connectors, mechanical joint caused by OTDR receiver saturation and bring a series of 'blind spots' called blind spots. Optical fiber in the blind area is divided into events blind area and attenuation blind area of two types: due to intervention activities connector reflection peak, from the starting point of the reflection peak to peak value of the length of the distance between receiver saturation, known as event blind area; Due to the intervention activities in optical fiber connectors cause reflection peak, from the reflection peak to other events to recognize the point, the starting point of the distance, is called attenuation blind area. For OTDR, certainly blind area as small as possible. Blind area will increase with the increase of the width of pulse broadening and, increasing the pulse width while measuring length, but also increases the measuring blind area, therefore, optical fiber, the tests of OTDR attachment to use of optical fiber and adjacent point of narrow pulse, and from time to time to use to measure the optical fiber remote pulse width.