Comparison of the sensitivity of air and dielectric modes in photonic crystal slab sensors

Optical cavities provide a route to sensing through the shift of the optical resonant peak. However, effective sensing with optical cavities requires the optimization of the modal quality factor, Q, and the field overlap with the sample, f. For a photonic crystal slab (PCS) this figure of merit, M =fQ, involves two competing effects. The air modes usually have large f but small Q, whereas the dielectric modes have high-Q and small f. We compare the sensitivity of air and dielectric modes for different PCS cavity designs and account for loss associated with absorption by the sensed sample or its host liquid. We find that optimizing Q at the expense f is the most beneficial strategy, and modes deriving from the dielectric bands are thus preferred. ©2009 Optical Society of America

Broadband and robust optical waveguide devices using coherent tunnelling adiabatic passage

We numerically demonstrate an optical waveguide structure for the coherent tunnelling adiabatic passage of photons. An alternative coupling scheme is used compared to earlier work. We show that a three rib optical waveguide structure is robust to material loss in the intermediate waveguide and variations to the waveguide parameters. We also present a five rib optical waveguide structure that represents a new class of octave spanning power divider

Design of high-Q Cavities in Photosensitive Material-based Photonic Crystal Slab Heterostructures

Abstract-We propose a novel concept for creating high-Q cavities in photonic crystal slabs (PCS). We show that photonic crystal slab-based double heterostructure cavities, formed by variations in the refractive index, can have large a Q-factor (up to Q = 1 × 10 6 ), and that such cavities can be implemented in chalcogenide glasses using their photosensitive properties. DOI: 10.2529/PIERS060907042030 In the last few years the study of optical microcavities based on photonic crystal slabs has attracted much attention A cavity is usually formed in either of two ways: forming a point cavity or forming a "heterostructure". Microcavities with the highest Q values achieved to date, have been realised through the use of photonic crystal double-heterostructures The concept of the cavity design in hetero-structures relies on the mode-gap effect, a narrow frequency range for which PC 2 supports a mode, but not PC 1 . Therefore, first we determine if there is a sufficient mode-gap to support a localized state between the structures having different refractive indices. We introduce a W1 waveguide in these structures: W1 1 for PC 1 with n = 2.7, and W1 2 for PC 2 with n = 2.75. Using the Plane Wave Expansion method, we obtain the dispersio

Room-temperature single-photon emission from zinc oxide nanoparticle defects and their in vitro photostable intrinsic fluorescence

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Slow-light switching in nonlinear Bragg-grating coupler

We study propagation and switching of slow-light pulses in nonlinear couplers with phase-shifted Bragg gratings. We demonstrate that power-controlled nonlinear self-action of light can be used to compensate dispersion-induced broadening of pulses through the formation of gap solitons, to control pulse switching in the coupler, and to tune the propagation velocity.Comment: 3 pages, 4 figure

Depletion of nitrogen-vacancy color centers in diamond via hydrogen passivation

We show a marked reduction in the emission from nitrogen-vacancy (NV) color centers in single crystal diamond due to exposure of the diamond to hydrogen plasmas ranging from 700{\deg}C to 1000{\deg}C. Significant fluorescence reduction was observed beneath the exposed surface to at least 80mm depth after ~10 minutes, and did not recover after post-annealing in vacuum for seven hours at 1100{\deg}C. We attribute the fluorescence reduction to the formation of NVH centers by the plasma induced diffusion of hydrogen. These results have important implications for the formation of nitrogen-vacancy centers for quantum applications, and inform our understanding of the conversion of nitrogen-vacancy to NVH, whilst also providing the first experimental evidence of long range hydrogen diffusion through intrinsic high-purity diamond material.Comment: 6 pages, 3 figure

Dynamic stabilization of the optical resonances of single nitrogen-vacancy centers in diamond

We report electrical tuning by the Stark effect of the excited-state structure of single nitrogen-vacancy (NV) centers located less than ~100 nm from the diamond surface. The zero-phonon line (ZPL) emission frequency is controllably varied over a range of 300 GHz. Using high-resolution emission spectroscopy, we observe electrical tuning of the strengths of both cycling and spin-altering transitions. Under resonant excitation, we apply dynamic feedback to stabilize the ZPL frequency. The transition is locked over several minutes and drifts of the peak position on timescales greater than ~100 ms are reduced to a fraction of the single-scan linewidth, with standard deviation as low as 16 MHz (obtained for an NV in bulk, ultra-pure diamond). These techniques should improve the entanglement success probability in quantum communications protocols.Comment: 6 pages, 3 figures + Supplementary Info (4 pages, 3 figures

Deterministic optical quantum computer using photonic modules

The optical quantum computer is one of the few experimental systems to have demonstrated small scale quantum information processing. Making use of cavity quantum electrodynamics approaches to operator measurements, we detail an optical network for the deterministic preparation of arbitrarily large two-dimensional cluster states. We show that this network can form the basis of a large scale deterministic optical quantum computer that can be fabricated entirely on chip.Comment: 9 pages, 10 figures, minor revision

Microfluidic photonic crystal double heterostructures

We demonstrate postprocessed and reconfigurable photonic crystal double-heterostructure cavities via selective fluid infiltration. We experimentally investigate the microfluidic cavities via evanescent probing from a tapered fiber at telecommunication wavelengths. Fabry-Ṕrot fringes associated with modes of the induced cavity are in good agreement with the theory. We also demonstrate a cavity with quality factor Q=4300. Our defect-writing technique does not require nanometer-scale alterations in lattice geometry and may be undertaken at any time after photonic crystal waveguide fabrication. © 2007 American Institute of Physics

Resonant enhancement of the zero-phonon emission from a color center in a diamond cavity

We demonstrate coupling of the zero-phonon line of individual nitrogen-vacancy centers and the modes of microring resonators fabricated in single-crystal diamond. A zero-phonon line enhancement exceeding ten-fold is estimated from lifetime measurements at cryogenic temperatures. The devices are fabricated using standard semiconductor techniques and off-the-shelf materials, thus enabling integrated diamond photonics.Comment: 5 pages, 4 figure