What is Optical Return Loss
Feb 20, 2023| What is Optical Return Loss
When light encounters any section or uneven refractive index distribution (n) during transmission, such as Air Gap, misalignment, it will cause reflection. The calculation formula of Return Loss is as shown in the figure below, where Pr is the reflection of the original path The returning optical power, Pi is the forward transmitting optical power. The larger the value, the smaller the reflected energy.
Effect of return loss on the system
When the signal uses light waves as the carrier and encounters reflection during transmission, it will cause two impacts on the system:
1. The noise generated by the reflected light source will inhibit the S/N ratio of the transmitted signal;
2. Reflected light energy will broaden the pulse of the luminous system (Laser Source), causing the luminous system to be unstable;
For a system with more than two cross-sections, two or three reflections may occur due to the discontinuity of the refractive index. It is necessary to consider the interference effect and various losses caused by the change of light intensity or wavelength. Mainly caused by the following two:
a. Optical fiber end face gap loss;
b. Reflection caused by multiple reflections (Fresnel reflection) at the fiber end face.
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