Silicon photonics is a research field in full expansion that works towards the integration of photonics and microelectronic components in a single chip. The creation of a broadband optical link that is able to carry high-speed information requires the development of efficient building blocks compatible with CMOS technology. The work carried out during my Ph.D. focused specifically on silicon optical modulators for high-speed applications from 10 to 40 Gbit/s. The work presented includes design, optimization, fabrication and characterization of the complete device. The modulator is based on the electro-refractive effect obtained by depletion of carriers in PN and PIPIN diodes to obtain a phase change of the optical mode. Intensity modulation is obtained by integration of the active region in a Mach-Zehnder interferometer or a ring resonator. Electrical, optical and radio frequency simulations were conducted on the various elements of the modulator to design a device for FTTH (Fiber To The Home) applications operating at 127 µm. Additional studies included the design of RF coplanar waveguide electrodes optimized through the development of an electro-optical model that takes into account the propagation of the electrical and optical waves in the active region. Compatible CMOS processes were proposed, and the necessary masks for fabrication were designed considering fabrication tolerances and critical parameters. Finally, various experimental results were obtained on components designed at IEF and fabricated at CEA-LETI. We can specially mention a Mach Zehnder modulator operating at 40 Gbit/s that uses a PIPIN diode to obtain an index variation, and having an extinction ratio of 7.5 dB and losses of only 6 dB. The goal of future optimizations of silicon modulator is to integrate these devices with the RF driver, and to move towards more complex and efficient modulation formats than the two-level intensity modulation seen so far.
