Difference in Back Reflection at 45 degrees and 41 degrees

In the case of 45-degree polishing, the beam is emitted perpendicularly below the fiber, but the back-reflected light from the bottom of the fiber returns to the SMF and light source along the same optical path and at the same angle.

In the case of 41-degree polishing, the light is emitted slightly in front of the fiber tip, and the back-reflected light from the bottom of the fiber hits the angled polished surface at a different angle than the emitted light. According to Snell’s law, the light is propagated as “stray light” along a different optical path from the outgoing light.

This reflection and propagation reduces the noise of the back-reflected light, so TOYO recommends 41-degree polishing and makes it our standard.