Ultraintense and ultrashort light pulses have a huge potential for applications, such as the production of very compact particle accelerators. Exploiting this potential requires pushing the characteristics of lasers beyond their present state-of-the-art performances. However, the laser technology used so far is approaching its limits, in particular because of the optical breakdown of conventional optical media. Overcoming these limits requires finding radically new approaches for optics at ultrahigh laser intensities. The idea of this proposal consists in developing optical elements based on plasmas, i.e. plasma optics . Since plasmas are already ionized, they can sustain electromagnetic fields of extremely large amplitude. They can thus be exploited to produce several key optical elements needed to manipulate e.g. shorten, convert in frequency, or even amplify- existing ultraintense lasers. To this end, two main physical processes are exploited: laser-excited Langmuir waves, and the Doppler effect associated to the relativistic motion of plasmas in ultraintense laser fields. This project would contribute to the conception of a system consisting in a chain of several plasma optics, placed at the output of a table-top laser, which would deliver few-optical-cycle long PetaWatt-class near-visible light pulses, as well as Terawatt-class attosecond pulses in the soft x-ray range. Such light sources would open exciting perspectives in Science and Technology. More fundamentally, this project will exploit the coherent light emission induced during relativistic laser-plasma interaction as a fine probe of the ultrafast plasma dynamic. This new type of diagnostic should lead to significant progresses in the understanding of laser-plasma interaction at extreme laser intensities.