Single-mode transmission principle of step-index fiber
In step index single mode fiber, the core diameter is extremely small, that it allows only one mode to propagate through it. The V-number is defined as You need more refined tools to check the single-mode condition for non-step-index profiles! where λ is the vacuum wavelength, a is the radius of the. Each mode will propagate in the fiber at as if it had its own index of refraction n.
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