Instead of a contact end face which is perpendicular to the fiber axis the end face is manufactured so that it is at an angle of 8º to the axis.
Apc fiber connector angle.
Connectors with apc finishes are made by polishing the fiber at either an 8 or 9 degree angle with a radius of curvature between 5 and 12 mm see figure 1.
Another more obvious difference is color.
With upc the fiber ends are more rounded than the pc finish giving greater contact between the glass surfaces.
Apc connector is a type of fiber connector that minimizes backreflection due to a 5 to 15 angle polish applied to end faces.
With upc connectors any reflected light is reflected straight back towards the light source.
Apc connectors are polished at an 8 degree angle.
However the angled end face of the apc connector causes reflected light to reflect at an angle into the cladding versus straight back toward the source.
Sc apc connector is polished with an 8 degree angle while sc upc connector is polished with no angle which causes difference in light reflection.
Because of the angle the reflected light does not stay in the fiber core but instead leaks out into the cladding.
Upc connectors are blue while apc connectors are green.
They have a slight curvature for better core alignment.
Upc connectors are polished with no angle but are slightly curved for better core alignment.
Upc connectors are not exactly flat however.
Like illustrated in the following picture.
Upc connectors are blue while apc adapters are green.
Any reflection light bounces back from the interface at 16º to the axis which is greater than can be constrained by the fiber core cladding interface so is thus lost.
Angled polished physical contact apc also called as apc fiber connector is best for high bandwidth applications and long haul links since it offers the lowest return loss rl characteristics of connectors currently available.
This causes some differences in return loss.
By angle polishing the end of the fiber one ensures that reflections at the fiber air interface are not captured by the fiber core.
Upc connectors are polished with no angle.
Upc connectors are polished with no angle but apc connectors feature a fiber end face that is polished at an 8 degree angle.
The apc connector is altogether much more crafty.
The apc stands for angled physical contact because these connectors allow the surfaces of two connected fibers to be in direct contact with each other and because the fiber end is polished at an angle to prevent reflected light from traveling back up the fiber.
Apc connectors feature a fiber endface that is polished at an eight degree angle.
Sc upc connector adopts an extended polish method to realize finer fiber surface finish which brings much lower back reflection orl and thus provides much more reliable signal in data center digital tv and telephone.