Control òptic de bandes fotòniques en materials E.I.T

We intend to investigate the effect of a periodically space-modulates dispersion pattern on the propagation of an incident light pulse. The principles of such an effect can be illustrated by employing EIT (Electromagnetically Induced Transparancy) materials driven in a standing-wave (SW) pump configuration [1,2]. We will examine special classes of intrinsic semiconductors (Cu2O, CuCI) and doped crustals (Pr:YSO) exhibiting a large EIT effect [3, 5]. This is expected to lead to non-traditional photonic band-gap structures the nature of which will be thoroughly investigated. A similar investigation will be carried out for ultracold samples of alkali atoms whose band-gap will display an even richer structure [6]. Periodically space-modulates absorption and dispersion patterns can be easily varied with time which would allow to realize a tunable photonic band-gap. EIT media are known to exhibit giant Kerr nonlinearites [7]. We intend to exploit this feature to propose the realization of all-optical polarization qubit logic gates [8-10]