04 May 2017 Schäfter+Kirchhoff offer different fiber couplers for collimating the beams exiting polarization-maintaining (PM) and singlemode fibers, as well as for coupling into PM fibers from free space (type 60FC) or with a coupler directly attached to the laser (type 60SMS).
The optimum focal length of the coupling optics depends both on the beam diameter and the NA of the fiber. Thanks to the large variety of optics, with focal lengths ranging from 2.7 mm up to 200 mm, a high coupling efficiency or a designated beam diameter can be achieved for various different beam diameters and a large wavelength range.
This large range of optics includes many different achromats, where the chromatic aberration has been corrected or minimized for a certain wavelength range, allowing for example the fiber coupling of 400-660nm light together into one fiber with high coupling efficiency for all wavelengths. Additionally, all achromats possess a broadband AR-coating with small residual reflectivity and are corrected for spherical aberration as well. In contrast with aspherical fiber couplers, that show a fine structure in the collimated beam because of their manufacturing process, the achromatic fiber couplers have an undisturbed profile in the collimated beam as well as in the focus.
All fiber couplers can be focused either using an eccentric key or a fine thread (type 60FC-F) and are available for different fiber connectors (FC-APC, FC-PC, DIN-AVIO, F-SMA und ST). For fibers with an angled polish, the fiber couplers have an inclined coupling axis. The fiber couplers of type 60SMS also feature an integrated tilt-adjustment, whereas the fiber couplers of type 60FC are UHV compatible. Both types are also available in amagnetic titanium. | 
