Etude et réalisation d’un micro-collimateur à fibres optiques à microlentille semi- ellipsoïdale

Abstract

This thesis aims to evaluate the capability of the micro-collimator in its functionality as an emitter and collector of light excited with a laser diode. The chosen structure consists of a fiber with a semi-ellipsoidal end. Although much research has been carried out into the manufacture of these precision components at the end of optical fibers, these methods still need to be improved. The main issue is the mismatch between the modes of the optical fibers and the optoelectronic components used in the optical systems. This problem of shaping the laser source-fiber interface therefore requires an advanced, simple, reproducible and inexpensive innovative technology for shaping the beam from the laser source and focusing it into the fiber core. Thus, we propose a new technology to fabricate and characterize micro- collimators based on semi-ellipsoidal microlenses on the end of SMF single-mode fibers, related to the propagation of light in standard optical telecommunications fibers via focusing optical systems. The optical characterization of the microlenses show that a selection of the mode diameters of the micro-collimators can be obtained, ensuring a better mode matching of the fibers and lasers by optimizing the opto-geometric parameters. The advantage of this manufacturing technique is the possibility to control the ellipticity ratio of the microlenses, allowing in effect to correct the ellipticity of the laser mode propagating in fibers. This approach therefore has the advantage of controlling the beam ellipticity.