This thesis deals with the update of the system for the measurement of optical cladding attenuation. The update was necessary due to poor repeatability. We suspected that not all exit light from the laser fibre falls on the detector of optical spectrum analyser.
Numerical aperture of the fibre plays a great role when measuring the attenuation and setting up the measuring system for the attenuation. The numerical aperture of the optical fibre is around 0.48; consequently, the fibre has also a wide exit beam. This is why we must ensure that all the light falls on a detector otherwise the measurement is incorrect. This was the problem of the old system. The fibre with such large numerical aperture was too far away from the detector.
In the new system, I included a chopper, a monochromator, a lock-in amplifier, a xyz table and a new detector. The detector and the xyz table are essential. I placed the xyz table in front of the suitably large detector and the fibre could fastened on the table. The fibre was then able to approach the detector and I prevented the leakage of the exit beam out of the detector. I made additional two test measurements to check the repeatability.
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