Future optical modulators have to satisfy requirements that current electro-optical modulators fail to do, such as very low command voltage, small size and ability to work in the 0-40GHz range with low losses. It is also necessary to find new ways to modulate light at a faster speed but with low consumption. The work in this thesis addresses these above mentioned problems within the framework of an upstream project which has been financed by the French Ministry of Defence. Its goal is to evaluate the potential gain of plasmonics in the field of semiconductors based optical modulation. We first select a gallium nitride based structure on sapphire whose optical properties exhibit very low propagation losses of 0.6dB/cm. Then we proved the generation of a plasmonic wave for a Au/GaN interface. Optimizations were conducted to get the most effective modulation by varying optical index of the semiconductor. Several devices were fabricated in clean room and were characterized. Results obtained in optical measurements proved the effect of electric field in varying the optical index of GaN until 10-2 for tens of volt; however, RF propagation losses were high, about 16dB/cm for 20GHz. In addition, an electro-absorption structure using multi-quantum wells on InP substrate shows index variation of the order of 2×10-3 for only 2.5V by the prism-coupling technique. This thesis work, which has been the very first one in this domain in this laboratory, will pave the way for future research into new materials for optoelectronic applications and highlight the critical issues of the use of plasmonics for optical modulation in semiconductors.
