Toward photon storage inoptically driven color centers in diamond

An ever increasing effort has been devoted over the years to develop techniques for manipulating light in optical devices. Electromagnetic induced transparency (EIT) is one of these techniques that has recently led to an astonishing control on light wave propagation in ultracold clouds of alkali atoms. EIT may be employed to realize a photonic band gaps that are controllable through the parameters of an external standing light wave pattern [1]. Such gaseous approaches are not however suitable for on-chip implementation. Early work on control over photonic band-gap comprises, e.g., structures built from the periodic complex susceptibility of quantum well excitons whose optical properties can be dynamically modified through the Stark effect. Other interesting proposals to control photonic band-gaps in semiconductor heterostructures have been brought forward and where control over the band-gap is achieved through EIT in conduction intersubband transitions of a n-doped quantum well. EIT effects have also been observed in a class of solid materials exhibiting defect states, following either familiar or less familiar schemes, and among which presodimium doped Y2SiO5 and diamond containing nitrogen vacancies (N-V) color centers are perhaps the most ubiquitous ones. Color centers in diamond, in particular, have attracted over the past few years a renewed interest for their potential as single-photon sources and are attractive qubit candidates as they behaves a bit like an atom trapped in the diamond lattice. These centers can have extremely long-lived spin coherence because the diamond lattice is composed primarily of 12C, which has zero nuclear spin. In addition, N-V color centers also have interesting optical properties as they exhibit a configuration with two ground state levels connected to a common excited state by optical transitions of moderate strength leading to a lambda-type level configuration required for the observation of EIT [2,3]. This has been exploited to devise a novel photonic band-gap mechanism [4]. We here study the propagation of a very week optical pulse in the band-gap region of N-V diamond crystals. Our calculations show that adopting realistic parameters, as taken from recent experiments on coherent population trapping in N-V color centers, nearly complete reflectivities can be attained in a mm long diamond sample. This occurs when most probe frequency components lie inside the band-gap, yielding instead controllable loss and distortion as the incident probe pulse falls outside the gap. The relevant photonic band-gap may be all optically controlled while its well developed structure is seen to arise from the reduced values of residual absorption in the EIT region. [1] M. Artoni et al., Phys. Rev. Lett. 96, 073905 (2006). [2] C. Wei et al., Phys. Rev. A 60, 2540 (1999). [3] P. Hemmer, et al.,Opt. Lett. 26, 361 (2001). [4] Q.-Y. He, et al., Phys. Rev. B 73, 195124 (2006).