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We present measurements of two-dimensional photonic crystals in a waveguided geometry, using photoluminescence from emitters inserted in the guiding heterostructure as an internal light source. A complete set of measurements is given, including quantitative evaluation of the transmission, reflection and also diffraction coefficients of the samples. Their behaviour is shown to follow mostly the pure 2D theory. Capitalizing on the measured properties, we fabricated one-dimensional cavities. The cavity modes are probed through transmission measurement. The measured quality factor leads to an estimation of the reflectivity of the mirror of the order of 95%. We also designed and fabricated disk cavities surrounded by circular Bragg mirrors. The resonances are probed by exciting the photoluminescence of quantum dots placed inside the cavity. Resonances with quality factors up to 650 are found corresponding to the confined Quasi-Radial Modes. [ABSTRACT FROM AUTHOR]

If the improvement of computation continues at anything like the pace that it has set over the last fifty years, within a few decades we will have devices of atomic dimensions. Quantum computing, in which bits, in their atomic embodiment, can exist and be manipulated in a coherent superposition of computational states, is one possible method for fundamentally improving computing once the atomic scale is reached. I illustrated some of the design principles of quantum gate constructions, using the two-bit adder as a simple example. Some details of the Shor prime factoring algorithm are discussed. [ABSTRACT FROM AUTHOR]

We use the modifications of spatial mode distributions in planar microcavities to address the issue of light outcoupling in devices such as LEDs. Whereas detailed calculations are needed to fully model and optimize the structures, we show that a simple picture can be obtained that clarifies the main physical effects of the microcavity. In particular, it is shown that the cavity order mc is the chief parameter in determining the extraction efficiency according to η=1/mc under some reasonable, simplifying assumptions. When the source in the cavity has a linewidth, light redistribution among both angles and wavelengths occurs and can either be a limiting factor for the overall extraction efficiency or a positive one in case of spectral narrowing requirements. In extraction-optimized systems, one gains a factor of up to ten on the single-face extraction as well as brightness (radiance). [ABSTRACT FROM AUTHOR]

Most of the work on photonic crystals has been devoted to the study of the linear optical properties of these refractive index heterostructures. In this lecture, the use of optical heterostructures for nonlinear optics and in particular frequency conversion is reviewed. A key issue for frequency conversion is the possibility of phase matching, that is to compensate for optical dispersion, which results in different phase velocities for light of different frequencies. Various optical heterostructures, which can be used for phase matching nonlinear interactions, are described. A first way consists of engineering form birenfringence in a composite multilayer material. In that case the different waves propagate in the plane of the layers, and phase matching is obtained by making use of the different dispersion relations for two perpendicularly polarized Bloch waves. Generalization of form birefringence phase matching in two-dimensional (2D) photonic crystals is discussed. Quasi phase matching (QPM) is another possibility, which has achieved considerable success for instance in periodically poled LiNbO3: in that case, the propagation is perpendicular to a one dimensional multilayer system of periodic nonlinear susceptibility. QPM can be generalized in 2D: the possibilities offered by frequency conversion in a 2D photonic crystal of χ(2) are discussed. Interesting perspectives are opened with this kind of 2D nonlinear interaction, described by a nonlinear Bragg law. [ABSTRACT FROM AUTHOR]

We discuss sources of single photons for quantum information processing. For limited applications the attenuated laser is an adequate source. Further improvement would be obtained from single atom or molecule emission. Collection efficiency into a narrow band and single mode could be improved by photonic bandgap material surrounding the emitter. We discuss a measurement showing light emission from single dye molecules modified by planar cavity. Another source could be time gated single photons created from the parametric downconversion process. We go on to show a simple interference effect between separate single photons that confirms the quantum nature of this source. [ABSTRACT FROM AUTHOR]

We discuss the recent observation of a strong enhancement of the spontaneous emission rate (Purcell effect) for self-assembled InAs/GaAs quantum boxes inserted in GaAs-based pillar microcavities or microdisks. [ABSTRACT FROM AUTHOR]

We discuss recent experiments in cavity QED with strongly coupled single atoms, studied one at a time, in real time. Particular emphasis is placed on defining what is, and is not "quantum" about particular parameter regimes of the system. [ABSTRACT FROM AUTHOR]

An overview of the theory of the linear optical response of planar semiconductor microcavities with embedded quantum wells is presented. In particular, the optical properties close to the excitonic transition in the strong coupling regime are addressed and the formalism of exciton polaritons is used. First, the transfer matrix formalism is introduced in order to solve Maxwell equations for the Fabry-Pérot microcavity with distributed Bragg reflectors and to study the cavity mode features. Then, the coupling to a quantum well excitonic resonance is included within the semiclassical formalism for the optical response. The main qualitative and quantitative features of microcavity polaritons are illustrated through several calculated optical spectra and, afterwards, a more formal description of the polariton modes is provided. Finally, the problem of the full quantum description of the exciton photon coupling is briefly addressed. The quasimode formalism is introduced and, as an example of application, a simple model for microcavity photoluminescence under nonresonant continuous wave excitation is presented. [ABSTRACT FROM AUTHOR]

This paper reviews the theory needed to describe the near bandgap optical properties of semiconductor quantum-well structures. After brief introductions of the basic concepts of electronic banstructures, quantum confinement effects, and optical susceptibility, a systematic derivation of the semiconductor Bloch equations is presented. In the regime of linear response the excitonic and Coulombic enhancement effects in the absorption spectra of direct-gap semiconductor structures are discussed. Nonlinear phenomena, such as absorption saturation, gap renormalization and excitation induced dephasing are analyzed using a systematic scheme of approximations. The resulting nonlinear semiconductor theory is self-consistently combined with solutions of Maxwell's equations to compute the optical properties of excitonic semiconductor microcavity systems. [ABSTRACT FROM AUTHOR]

This chapter discusses, in a tutorial way, the basic theory of electromagnetic emission by a dipole in a planar cavity, which is representative for the spontaneous emission in micro-cavity LED's. We start from the expansion of a point source field into plane waves. Then the enhancement and inhibition effects of a cavity upon plane wave components are introduced. Next. the vectorial aspects af dealing with a dipole field are discussed, as well as the effects caused by the use of realistic mirrors. Finally we describe the effect of the cavity upon the carrier lifetime and give a discussion of guided modes. More in particular the plane wave decomposition and normal mode decomposition are confronted with each other. [ABSTRACT FROM AUTHOR]

This very rapid overview of quantum electrodynamics in the optical range has allowed us to give a first insight concerning some basic physical phenomena of the domain, and to precise the validity conditions of the different approximations. It has also missed many others, which could not fit within such a short series of lectures. Let us mention briefly some of them:the non resonant atom-cavity interaction, leading to electromagnetic field phaseshifts dependent on the atomic state, or to atomic coherence phase factors dependent on the field state.the tailoring of atom-field quantum correlations, leading to quantum non demolition measurement of field observables and to the very active domain of "quantum computing".the radiative forces due to the atom-field coupling, which have also a nonclassical character (Casimir force between mirrors, trapping force due to the vacuum field, …).the micromaser, in which excited single atoms are continously sent in the cavity mode. All these fascinating subjects (and some others) are presented in the references [4, 6, 49, 50, 44]. [ABSTRACT FROM AUTHOR]