Numerical Aperture Mismatch Loss, also known as NA Mismatch Loss, is a loss of power at a joint that occurs when the transmitting end of a cable has a numerical aperture (NA) greater than the numerical aperture of the receiving end of the cable. This type of loss occurs when light is being coupled from one source to another, such as when light is being transmitted from a source to a fiber optic cable, from one fiber optic cable to another, or from a fiber optic cable to a detector.
NA Mismatch Loss can occur when two cables with different NA values are connected together. The NA value is a measure of the light-gathering ability of the cable’s endface, and is determined by the cable’s core and cladding size, as well as the refractive index of the core and cladding materials. A larger NA indicates a greater light-gathering capacity, and thus a higher amount of power. When two cables with different NA values are connected, the larger NA will be the limiting factor, resulting in lower power throughput at the joint.
To minimize power loss due to NA Mismatch Loss, it is important to ensure that the cables being connected have the same NA value. This can be done by checking the specifications of the cables to ensure that they have the same numerical aperture, or by inspecting the cables’ endfaces to make sure they have the same size core and cladding. It is also important to use quality connectors and cables that have been designed to reduce losses due to NA Mismatch Loss.
In short, NA Mismatch Loss is a loss of power that occurs when two different cables with different numerical apertures are connected together.