The beat length in a single mode optical fiber is 8 cm, when light from a laser with a peak wavelength 0.6?m is launched into it. Estimate the modal birefringence.

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Quizplus · Accepted Answer

The beat length is given by:$$L_b=\frac{\lambda^2}{2\Delta n}$$where:* $L_b$ is the beat length* $\lambda$ is the wavelength of light* $\Delta n$ is the modal birefringenceSubstituting the given values into the equation, we get:$$8	imes10^{-2}	ext{ m}=\frac{(0.6	imes10^{-6}	ext{ m})^2}{2\Delta n}$$Solving for $\Delta n$, we get:$$\Delta n=1	imes10^{-5}$$

The Beat Length in a Single Mode Optical Fiber Is