Un contrôle de température réduit de façon significative le phénomène de dérive de l'EOM. Nous avons étudié les influences de la température sur le modulateur électrooptique (EOM) et sur le comportement global de l'OEO. S'il n'est pas bien optimisé ni contrôlé, il ne peut pas fonctionner correctement sur une longue durée. Compte tenu de sa structure l'OEO dépend fortement des conditions ambiantes d'utilisation. Dans cette thèse nous étudiants plusieurs aspects de l'OEO pour son application à la mesure d'indice de réfraction d'un liquide. Mais l'OEO devrait aussi pouvoir être utilisé dans le domaine des capteurs. Les développements de l'OEO concernent les applications en photonique microondes, télécommunications optiques, radar et traitement du signal. Maleki, en tant qu'oscillateur microondes à très faible bruit de phase et obtenu par synthèse directe. L'oscillateur optoélectronique (OEO) a été introduit pour la première fois en 1996 par S. Therefore the signal-to-noise ratio in the refractive index measurement can be enhanced and so the detection resolution of the refractive index variations during time. Introducing by this way a correction to the long-term frequency measurement it is possible to reduce the oscillation frequency fluctuations to only 606 Hz, compared to the 8 GHz of the oscillator, for a duration of 62 hours. Finally, we have introduced a new method to improve the long-term refractive index measurement by monitoring, with a vector network analyzer, the variations of the optical delay in the fiber loop of the OEO. The results are in rather good agreement with previous publications. Using like that the OEO, we have tested several configurations to measure the refractive index of four classical chemical solutions leading to a standard deviation of 3 per thousand. A combination of these two techniques can take advantages from both of them. The second one is based on the average optical output power of the EOM. The first technique is based on a dither signal at low frequency, injected to DC electrode of the EOM. In order to totally remove this drift, we have developed a complete digital system, based on a DSP kit, to detect and compensate automatically the EOM optical bias point drift and to control simultaneously its temperature. Temperature control can significantly reduce the drift phenomena of the EOM. We have analyzed the influences of temperature on the electrooptic modulator (EOM) and the global OEO behavior. If the OEO is not optimized and controlled, it cannot operate well for long duration.
Because of its structure the OEO is very dependent on the ambient conditions. In this thesis, we study several aspects to apply the OEO to liquid refractive index measurement. The OEO developments concern applications in microwave photonics, optical telecommunication, radar and high speed signal processing systems but it should also be used in the sensing domain.
Maleki as a very low phase noise microwave oscillator working in direct synthesis. The optoelectronic oscillator (OEO) was first introduced in 1996 by S.
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