The fiber coupler series 60FC-SMA is designed for coupling into SMA-905 high
power connectorized single-mode and polarization-maintaining fiber cables including
PCF fibers cables. It can also be used to collimate radiation exiting such fiber
cables. Please note that the collimated beam profile strongly depends on fiber
properties and is not Gaussian for PCF fibers.
The features of the coupler type 60FC-SMA include:
Optics
The
monochromat
with focal length 60 mm is designed for collimating
single wavelengths. It is AR-coated from 390 - 670 nm. It is
corrected for spherical aberrations and designed in such a way that it leads to
a diffraction-limited beam with an M2 < 1.05. The focus position varies strongly
with wavelength so that the collimator has to be recollimated after any changes to
the wavelength. It is not suitable for UHV applications.
Adjustment of focus and TILT
The distance between fiber end-face and collimating optics is adjusted by means of
an eccentric key. The lens does not rotate when adjusting the focus. The final focus
setting is locked by means of two radially arranged clamping screws. Additionally
attachment optics of series 60FC-SMA can be mounted to the front of the collimator.
Additionally, the collimator has an integrated TILT adjustment. Unlike common
FC-type connectors, the SMA-905 High Power Connector does not have a spring-loaded
ferrule. With varying ferrule length, the point of emission not only shifts axially,
but also laterally with respect to the optical axis in the case of an inclined
polish (5° and 8° -polish). By using the TILT adjustment, the point of emission can
be adjusted onto the mechanical axis of the fiber coupler. When collimating a laser
beam, the integrated TILT adjustment for the fiber coupler 60FC-SMA-T prevents
vignetting or diffraction arising from a clipped beam. When coupling into a fiber,
high efficiencies can only be reached when the tilt is adjusted properly.
Optimum lens performance
The angled polish of connectors of type SMA-905 with 5° or 8° is considered by a
pre-angled mechanical coupling axis that compensates the beam deflection and
you can use the lens centrically. This minimizes aberrations simply resulting
from a non-ideal beam path through the lens.
Connector Type
The fiber collimator is equipped with a F-SMA type receptacle. Unlike
the fiber collimators for FC-PC or FC-APC connectors (60SMS or 60FC-T) the fiber
connectors of type high power SMA 905 do not have an index key for alignment of
the polarization axis of the fiber cable. A groove in the collimator helps with
the manual axis alignment.
Material
The fiber collimator type 60FC-SMA is made from nickel silver/aluminium (standard)
Mounting
The collimator can be placed into a standard mirror mount
