NKT Photonics SuperK CONNECT, Product Manual, Page: 31 / 40

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4 Notes on Fiber Delivery
NKT Photonics can supply multiple Fiber Delivery types which can be
characterized by their fiber and connector types. This chapter includes
information discussing fiber types, coupler and collimator keying, mating fibers,
cleaning fiber facets and protecting them from contaminants.
Selecting standard or photonic crystal fiber delivery
Selection of the Fiber Delivery model depends on the application delivery
requirement and the transmission characteristics of each fiber type. Each FD
model is characterized by its output connector and fiber type.
Table 2 on
page 35 lists fiber models with their transmission characteristics. The selection of
the fiber will depend not only on the transmission characteristic required but also
the type of connector delivery to the end-application.
Wavelength
transmission
Standard Single Mode Fiber
Standard SMF grade fiber is a type of step-index fiber where the high-index core
is surrounded by low-index cladding. At the fiber’s cut-off wavelength, higher
order modes may be transmitted, contaminating the output light and possibly
causing unwanted inter-mode interference. This reduces the possible single-
mode transmission bandwidth. However, SMF fiber is flexible in that is supports
coupling with subsequent fibers through butt joints using FC type connectors.
Photonic Crystal Fiber
A key property of Photonic Crystal Fiber (PCF) is that it only allows transmission
of single mode wavelengths. Higher order modes are leaked due to a special
hollow channel arrangement that surrounds the central light guiding core. PCF
fiber is applicable where broadband single-mode guidance is required. It is,
however, not possible to butt joint PCF fiber, therefore coupling with subsequent
fibers is not possible using PCF as explained in the following section.
Connectors and mating fiber light guides
Output coupling
Standard Single Mode Fiber
The Numerical Aperture (NA) of single mode (SM) fiber facets is well-defined.
Because of this, SM fiber can be coupled using butt joints with a subsequent fiber
of an end-application, Connector types such as FC/APC, FC/PC and SMA can be
requested upon order.
Photonic Crystal Fiber
The air channels within a PCF fiber are subject to capillary effects which tends to
attract moisture to into them. To avoid this, the ends of PCF fibers are fused
together sealing the channels off. The fused end section of fiber is approximately
100 µm long. This causes the light guided within the core to scatter with a wide