Which statement best describes the relationship between ORL and reflectance?

Which statement best describes the relationship between ORL and reflectance?

• A. ORL is the total reflectance; Reflectance is per point
• B. ORL is per point; Reflectance is total
• C. They are the same
• D. ORL is forward loss

Answer: (A)

Optical return loss represents the total amount of light that is reflected back toward the source from every interface along the fiber, as measured at the input. Reflectance is a local property: it is the fraction of light that is reflected at a single interface or point along the path. Since many interfaces can exist, the total back-reflected power that contributes to ORL comes from all those points, whereas reflectance at each point can vary. So, ORL is the total reflectance of the link, while reflectance is defined per point. The idea that ORL is forward loss isn’t correct, because forward loss describes attenuation of light traveling forward, not light reflected back toward the source.

Optical return loss represents the total amount of light that is reflected back toward the source from every interface along the fiber, as measured at the input. Reflectance is a local property: it is the fraction of light that is reflected at a single interface or point along the path. Since many interfaces can exist, the total back-reflected power that contributes to ORL comes from all those points, whereas reflectance at each point can vary.

So, ORL is the total reflectance of the link, while reflectance is defined per point. The idea that ORL is forward loss isn’t correct, because forward loss describes attenuation of light traveling forward, not light reflected back toward the source.