Efficient light coupling from integrated single-mode waveguides to supercollimating photonic crystals on silicon-on-insulator platforms

We propose a practical and efficient solution for the coupling of light from integrated single-mode waveguides to supercollimating planar photonic crystals on conventional silicon-on-insulator platforms. The device consists of a rib waveguide, designed to sustain spatially extended single-modes and matched to a supercollimating photonic crystal, which has been truncated at its boundary to improve impedance matching between the two photonic components. Three-dimensional simulations show transmission efficiencies up to 96 % and reflections below 0.2 % at wavelengths close to 1.55 microns. This approach constitutes a significant step toward the integration of supercollimating structures on photonic chips.Comment: 11 pages, 4 figure

Studies of the photonic and optical-frequency phonon properties of arrays of selectively grown micropyramids

An array of GaN micropyramids containing a near-surface InxGa1?xN/GaN single quantum well has been fabricated using selective area epitaxial overgrowth above a patterned silica mask. The pyramid array has been studied by means of angle-resolved reflection measurements using s- and p-polarized incident light in the near- and mid-infrared optical ranges. We have found that the periodic array of flat-topped pyramids shows marked resonances in the near-infrared optical range due to resonant Bloch modes within the extraction cone and that the angular dispersion of these modes exhibits strong photonic crystal characteristics. The experimental results are in good agreement with the photonic band structure calculated using a scattering matrix formalism. The mid-infrared optical anisotropy properties of the micropyramids were investigated to probe the infrared active phonons of the pyramid array. The A1?LO? phonon of the InxGa1?xN/GaN single quantum well was identified and the InN mole fraction was estimated from the mode behavior

Enhancement of Visible Second Harmonic Generation in Epitaxial GaN-Based Two-Dimensional Photonic Crystal Structures

also in Virtual Journal of Nanoscale Science & Technology, March 1, 200

3D Numerical modeling of propagation losses of a single line-defect photonic crystal

International audienc

Characterisation of 2D photonic crystals cavities on InP membranes

We report on characterisation of optical modes in InP microcavities formed by two-dimensional (2D) photonic crystals (PC) on a suspended membrane. Diffracted photoluminescence (PL) experiments and numerical calculations are associated in order to analyse the properties of PC microresonators and waveguides and to investigate the coupling between these two building blocks of PC based photonic integrated circuits

Studies of the photonic and optical-frequency phonon properties of selectively grown GaN micro-pyramids

An array of GaN micropyramids containing a near-surface InxGa1-xN/GaN single quantum well has been fabricated using selective area epitaxial overgrowth above a patterned silica mask. The pyramid array has been studied by means of angle-resolved reflection measurements using s- and p-polarized incident light in the near- and mid-infrared optical ranges. We have found that the periodic array of flat-topped pyramids shows marked resonances in the near-infrared optical range due to resonant Bloch modes within the extraction cone and that the angular dispersion of these modes exhibits strong photonic crystal characteristics. The experimental results are in good agreement with the photonic band structure calculated using a scattering matrix formalism. The mid-infrared optical anisotropy properties of the micropyramids were investigated to probe the infrared active phonons of the pyramid array. The A1(LO) phonon of the InxGa1-xN/GaN single quantum well was identified and the InN mole fraction was estimated from the mode behavio

Reversible occurrence nets and causal reversible prime event structures

One of the well-known results in concurrency theory con-cerns the relationship between event structures and occurrence nets: anoccurrence net can be associated with a prime event structure, and viceversa. More generally, the relationships between various forms of eventstructures and suitable forms of nets have been long established. Goodexamples are the close relationship between inhibitor event structuresand inhibitor occurrence nets, or between asymmetric event structuresand asymmetric occurrence nets. Several forms of event structures suitedfor the modelling of reversible computation have recently been developed;also a method for reversing occurrence nets has been proposed. This pa-per bridges the gap between reversible event structures and reversiblenets. We introduce the notion of reversible occurrence net, which is ageneralisation of the notion of reversible unfolding. We show that re-versible occurrence nets correspond precisely to a subclass of reversibleprime event structures, the causal reversible prime event structures

Angular dispersion of photons and phonons in a photonic crystal of selectively grown GaN pyramids containing an InxGa1-xN quantum well structures

Angular-dependent reflection measurements were used to map out the dispersion relations of the resonant Bloch modes, and the angular dispersion of the phonon modes, in a photonic crystal consisting of selectively grown GaN pyramids containing a single InxGa1-xN/GaN quantum well. The dispersion of the photons exhibits strong photonic crystal characteristics, while the mean indium content of the 2 nm thickness InxGa1-xN layer was extracted from the angular dispersion of the phonon modes