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Features

• Resists Transmission Loss from UV Radiation
• Step-Index Multimode Fiber
• SMA905 Connectors on Both Ends
• Ø3 mm Orange Reinforced Outer Jacket

These fiber optic patch cables are similar to our other multimode SMA to SMA patch cables but incorporate solarization-resistant fiber for UV applications. Solarization refers to the formation of color centers within a fiber that lead to transmission degradation. These color centers form when exposed to light below 300 nm. Solarization-Resistant fibers are thus desirable when working in the UV due to their superior transmission and prolonged performance. Typical applications for these fibers are spectroscopy, UV photolithography, and medical diagnostics.

High-OH Fiber experiences significant transmission losses when exposed to UV radiation. In contrast, solarization-resistant fiber offers higher transmission. For optimal performance, expose the fiber to UV radiation for 5 minutes prior to use in your application to allow initial degradation. After this time, equilibrium is reached and the fiber can be used normally.

Each patch cable includes two protective caps that shield the connector ends from dust and other hazards. Additional CAPN Fiber Caps for SMA-terminated ends are also sold separately.

Numerical Aperture

Numerical Aperture (NA), a measure of the acceptance angle of a fiber, is a dimensionless quantity.  For applications, it is most commonly expressed as

where

is the maximum 1/2 acceptance angle of the fiber,

and

is the index of refraction of the material outside of the fiber; this material is typically air, making it equal to approximately 1.0, as shown in the figure below.

Figure: A ray at the maximum 1/2 acceptance angle propagates into a fiber.

Numerical Aperture can also be defined in terms of the index of refraction of the fiber core and the cladding. Due to Snell’s law, there is a critical angle above which all of the light at a fiber-cladding interface will be totally internally reflected. In turn, this means that there is a maximum acceptance angle at which light can enter the fiber. Following Snell’s law, the maximum acceptance angle can be determined:

Here,

is the index of refraction of the fiber core,

is the index of refraction of the cladding,

is the critical angle for total internal reflection,

and

is the maximum 1/2 acceptance angle.

This is the common way numerical aperture is defined for optical fibers. It is also important to note that these equations assume that a Gaussian beam is being outputted from the fiber.