Sample interview questions: Can you discuss your knowledge of the principles behind optical fibers and their transmission characteristics?
Sample answer:
Principles of Optical Fibers
Optical fibers are long, thin strands of glass or plastic that transmit light signals over long distances. They operate on the principles of total internal reflection, where light rays are guided through the core of the fiber by successive reflections off the inner surface of the cladding. The core and cladding have different refractive indices, ensuring that the light rays are confined within the core.
Transmission Characteristics
The transmission characteristics of optical fibers are determined by several factors:
- Attenuation: The loss of light power over distance due to absorption, scattering, and bending.
- Dispersion: The broadening of light pulses over distance caused by different wavelengths traveling at different speeds.
- Nonlinear Effects: Changes in the refractive index of the fiber under high optical power, leading to signal distortions and limitations on transmission capacity.
- Modal Behavior: The number of light modes (paths) that can propagate through the fiber. Single-mode fibers support only one mode, while multimode fibers support multiple modes.
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