Fiber bending test

A macro bend experiment
Theory Geometry optics analysis for Macro-bending：
In here, we can define two parameters for this system as θc is the critical angle and θ is incident.
Then, we can understand that will be two states happened at the bending area.One is the light pass through bending area fully similar to ray A when θ＞θc.Another is light out of bending area because the refraction was happened if θ＜θc.

Thinking and a simple experiment
ThinkingBased on the theory to think about our product, maybe we have a worse detection direction of photodiode to lead bigger insertion loss.Like the figure 1 showing, the maximum power direction perhaps is direction A not B, so I think that we can adjust the detection direction to reduce insertion loss.

A simple experiment
I do a simple experiment this morning, put a power meter at direction A and direction B then measure optical power individually：Direction A is more or less -25dBm.And direction B is the neighborhood of -27dBm.