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Fibre Coupling Solution for any PicoQuant Laser

Fibre Coupling

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Fibre Coupling Solution for any PicoQuant Laser

  • Available for all collimated free beam laser sources from PicoQuant (except below 350 nm)
  • Various fibre types: multi-mode, single mode and polarisation maintaining single mode
  • Various input and output connectors: FC/APC, FC/PC, SMA, High Power Fibre End-caps, others on request
  • Typ. 40–60 % coupling efficiency in (polarisation maintaining) single mode fibres
  • Typ. 80 % coupling efficiency in multi-mode fibres


Most laser sources from PicoQuant provide a collimated output beam1, including laser heads from the LDH, LDH-FA, and LDH-IX series as well as the high-powered VisIR and VisUV laser modules. All of these laser sources can be optionally coupled into a variety of optical fibres (such as multi-mode, single mode, or polarisation maintaining single mode) via different connector types. We recommend FC/APC connectors for most applications, since they prevent back reflections that can interfere with laser stability.

Fibre coupling for a laser head from the LDH-FA Series Why fibre coupling?
Coupling the laser beam into a fibre is useful to transport the beam light in a safe manner. But besides the prosaic function of light transportation, fibre coupling has the added benefit of improving the beam quality. For example, the typically elliptical beam shape of a collimated laser diode gets circularised into a round beam at the output of the fibre. Furthermore, coupling the light beam into a single mode fibre or a polarisation maintaining single mode fibre even permits to filter out all side modes of the diode in order to obtain a not only circular but also near TEMoo, gaussian distribution of the beam profile. In fact, for confocal microscopy setups, the coupling of a laser diode head into a polarisation maintaining single mode fibre is nearly a must.

Fibre coupling for a VisIR laser moduleCoupling efficiency
Note that fibre coupling does always lead to a loss in optical output power. The typical coupling efficiencies for elliptical laser diode beam shapes is 40 % for single mode and 80 % for multi-mode. The typical coupling efficiencies for fibre amplified laser beam shapes is 60% for single mode and 80 % for multi-mode in the visible/NIR range. At 355 nm the coupling efficiency in a single mode is typically of 50 %. Below 350 nm no fibre coupling is offered at the moment.

An optional collimator at the fibre output can also be provided upon request.

1 Except for a few butterfly-diode-based laser heads where a FC/APC receptacle is used as output (e.g., LDH-P-F-1030, CPDL-S-F-1060). Some lasers do come with a fixed output fibre by default such as the LDH-P-FA-530B.

Possible Fibre Types Typical Coupling Efficiency
Typical Coupling Efficiency
Typical Coupling Efficiency
Single mode fibre > 40 % > 60 % > 30 % for 2 wavelengths
Polarisation maintaining single mode fibre > 40 % > 60 % > 30 % for 2 wavelengths
Multi-mode fibre > 80 % > 80 % > 70 % for all 3 wavelengths
at 355 nm: 50 % for (PM) single mode, 80 % for multi-mode
< 350 nm: no fibre coupling!


[1] Different coupling efficiency into optical fibres for pulsed and CW operation due to astigmatism and possible wavelength shift. The coupling is optimised for pulsed operation as standard.


Direct emission Behind a multi-mode fibre Behind a single mode fibre
Laser diode heads from the LDH or LDH-I Series emit a collimated beam with an elliptical shape with typical dimensions of 1.5 × 3.5 mm When coupled into a multi-mode fibre, the beam shape at the fibre exit is nearly circular. The beam also displays a speckle pattern due to interference of multiple modes inside the fibre. Coupling a beam into a single mode fibre will change the beam shape at the fibre exit into a nice gaussian beam profile as only one mode is transmitted within the fibre.


The fibre amplified sources (LDH-FA, VisUV, VisIR) have mostly circular beam shapes with various beam diameters.


Connector types

  • FC/APC connectors are recommended for the majority of applications. The end of this fiber is cut by 8°, which minimises backreflections into the fibre that might interfere with the laser stability. This connector is therefore always used at the laser head and preferably as well at the output of the fibre.
  • FC/PC connectors have a flat output end. They might be necessary at the output of the fibre, if it needs to be connected to a device that also has a FC/PC connector. In such cases one should take care that the optical path of a possible back reflected pulse does not match the selected pulse period.
  • SMA connectors are only suited for multi mode fibres due to their limited fixation accuracy. They have a flat output end.


All Information given here is reliable to our best knowledge. However, no responsibility is assumed for possible inaccuracies or omissions. Specifications and external appearances are subject to change without notice.


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Fibre Coupling

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