7.7 Telecommunication

An ongoing revolution occurring in the field of telecommunications is the development of small laser diodes and high capacity optical fibers. Without telecommunication devices that use optical fiber, the highly convenient availability of huge amounts of information at comparatively low costs, as provided by the Internet, would not be possible.

The measurement of the power output of laser diodes or fibers is a daily routine in the field of telecommunication components testing. Optical power meters using a bare detector have a high sensitivity but at a cost of potential measurement inaccuracies caused by the effects of polarization, local saturation, signal ‘bounce-back’ and beam misalignment. In addition, the use of large sized photodiodes, which require the reduction of the source-to-detector-misalignment, increases costs.

A welcomed alternative is the integrating sphere. This is able to collect all of the source’s optical radiation output independent of beam geometry. In the world of photonics, the integrating sphere is well known for its ability to reliably and accurately measure total flux from fibers, laser diodes, lasers, LEDs, and any other optical radiation or light source. Since the incoming signal is captured as a whole and reflected inside the sphere multiple times before reaching the baffled detector mounted to it, the adverse effects of polarization, local saturation, signal ‘bounce-back’ and beam misalignment are reduced.