Realizing optical amplifiers with micro-sphere: A 15 dB gain, 2 dB noise-figure, tiny amplifier

We propose recently in a pan to use these objects as optical amplifiers. This aim requires working in a complete different direction. Firstly it is not suitable to have a good quality factor for the micro-sphere, because we want to avoid the lasing effect and the interferences between the many round-trip fields that will give a severe limitation to the optical bandwidth. Secondly, it could be interesting to have bigger sphere in order to have a higher gain. We present in this communication the fabrication of optical amplifiers [3] using 6000 ppm Er³⁺ Al-doped silica micro-spheres of diameters ranging from 200 mum to 3 mm. In a first step, 46 samples have been made in order to realize this study.