FIBERBENCH ALIGNMENT INSTRUCTIONS
The fiberports are provided in “nominal” position requiring just fine adjustment of alignment screws. Before trying to align the system fiberport to fiberport, you should follow procedures below:
- Assemble fiberbench with both ports on the fiberbench and facing each other.
- Launch light into input fiber. Using the camera or IR card, adjust the three pull screws in a near equal amount (0-80 SHC) so the “Z” positioning is fine tweaked to collimate the beam to your fiber. It may only require very small adjustment +/- half a turn of each screw, possibly up to one turn. Be Patient
Once good collimation is achieved, use slight +/- quarter or eight of a turn to steer the beam to center of other fiberport. If this adjustment is not enough, DO NOT adjust more. Set back to good collimation from step #2 and this time use x2 0-80 radial screws to move lens in X-Y to steer beam.
- Trick: Since the fiberbench for 1550nm can be aligned at 1310nm (if this is available to you), it is very helpful to do this at 1310nm since the 1310nm wavelength is more “visible” with IR cards and viewers. The last bit of alignment for optimal performance can be done at 1550nm.
Repeat #2-3 for other port launching light backward through output fiber.
To align fiberbench, start with MM 50-100um core fiber on the output port. This gives good practice in what adjustments help and how quickly you go in and out of alignment. It does not help to use MM fiber on the input port. If no MM fiber is available, it is not a problem. You just have to be patient.
The feedback to inform you of the coupling is to put output fiber into a detector. Some power should be present from steps #2-4 possibly only 10-250nW.
Once you have energy into the output fiber to detector, you can see improvements based on your adjustments. If the number does not improve, you can do two things.
- If you have no power, try launching into output fiber to see if power exits here.
- If you still have no power, try step #2-4 above again.
- If you still do not have any power, try to use 1310nm light if you have it.
- If none of this work and you do not still have any power, call OFR. We may need to provide you with MM fiber cable for practice and course alignment.
- Leave the fibers attached to the fiberbench assembly, disconnect the source and detector end and switch them so that the detector port is on the input side and the output side has the source.
- Tip: On a properly aligned system, the insertion loss should be the same in the forward direction as well as the in the reverse direction.
- Intentionally misalign both input and output fiberport by adjusting the XYZ to about 20% of the power, do not go below 20%. This gives you a new starting point to realign and start all over again and you will find that this time it should improve steadily.