The work presented here concerns the development of optoelectronic oscillators. Their high spectral purity is one of their most interesting qualities for photonics signal processing, communication or radio over fiber systems. The classical structure is based on a very long optical fiber loop acting as a delay line. Different techniques have been introduced, such as multiple loops, in order to get very narrow spectral lines and large mode spacing. Among the problems due to long fiber loops, there is the size and the requirement of temperature control. In order to go toward integrated solutions, it is also possible to introduce optical resonators instead of the delay line. Such resonators should present a very high quality factor in order to keep a low phase noise. Different solutions based on silica microspheres, on polymer materials or on silicon can be investigated. These resonators can be directly implemented with the associated Mach–Zehnder optical modulators in the case of both polymer and silicon materials.