Abstract : The development of the internet has generated a large increase in data transmission all over the world. To avoid an inexorable saturation of the telecommunication network, Dense Wavelength Division Multiplexing (DWDM) transmission, using optical signals at different wavelength in optical fibers, is one of the solutions to obtain a data rate up to 1Tbit/s. Routing these signals in this kind of network can be done using Optical Add Drop Multiplexers (OADM).
My PhD was concerned with the study and the construction of two different OADMs based on photoinduced Bragg gratings, which are actually optical filters written with an interference pattern of UV light on a photosensitive germanium doped optical waveguide. The thermal stability of these gratings and the origin of their photosensibility was also considered.
The first OADM studied was based on an integrated SiO2/Si coupler configuration including two Bragg gratings in the coupling zone of the coupler. The work consisted of improving the construction of the waveguide (getting a lower birefringence, lower loss...) as well as the photoinscription process (better apodisation of the spectral response of the grating, higher isolation...). The fabrication of the first prototypes, allowing the routing of channels separated by 200GHz, was then achieved.
The second study was about the optimisation of a twin-core fiber-based OADM, in which the Bragg gratings are placed in the central part of a Mach-Zehnder interferometer. Theoretical investigations, such as the study of the influence of the phase mismatch induced by the gratings on the interferometer, were carried out and lead to the improvement of the specifications of the component. Furthermore, a low value of the Bit Error Rate (BER) induced by the insertion of this OADM in a metropolitan network (2.5Gbit/s, NRZ signal) and negligible temperature and polarization sensitivities were measured, so that the first marketable items for routing data in networks with interchannel spacing of 100GHz and 50GHz were achieved at the end of my PhD.