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Slow light photonic crystal waveguides can be dispersion-engineered with an unprecedented degree of control over the group index, propagation loss and injection efficiency. Ultrasmall optical switches and substantial enhancement of nonlinear effects are demonstrated.Show More
The promising concepts of photonic microstructures are finally beginning to enter the realm of optical wavelengths: following a number of years of speculative theoretical work and experiments in the microwave regime, we present the first demonstration of strong photonic bandgap effects in semiconductors at optical wavelengths below 1 /spl mu/m. We have observed both short and long wavelength band-...Show More
We have shown that "all-solid" 1D and 2D oxide/semiconductor grating microstructures, with feature size of 1 /spl mu/m and 1:1 height:width aspect ratio, may be formed in a controlled manner by top-down pattern-masked wet-thermal oxidation of compositionally-graded AlGaAs layers. This approach is expected to have considerable impact in the fabrication of practical photonic lattice light-emitting d...Show More
We review some of the most promising methods for generating light in the silicon photonics context; nonlinear effects, defects, dopants and germanium alloying have all shown promise and can be enhanced using photonic crystals.Show More
We have investigated semiconductor (GaAs/AlGaAs) ring lasers with three different types of output coupler in order to identify the influence of the coupling geometry on the performance of such lasers. Ring lasers with multimode interference (MMI) couplers show significantly better characteristics than devices with Y-junctions and directional couplers. This improvement is explained by the high tole...Show More
Electromagnetic band structure can produce either an enhancement or a suppression of spontaneous emission from two-dimensional (2-D) photonic crystal thin films. We believe that such effects might be important for light emitting diodes. Our experiments were based on thin-film InGaAs-InP 2-D photonic crystals at ambient temperature, but the concepts would apply equally to InGaN thin films, for exam...Show More
A waveguide based microcavity exhibiting a quality factor Q/spl ap/2500 has been realized by incorporating a /spl lambda//4 phase shift into a 1-D photonic microstructure. The microstructure has an overall length of 3 μm, consists of a deeply etched grating with very narrow (75 nm) air-gaps and exhibits a third-order stop band in the 800-900 nm wavelength regime. A comparison between measurement a...Show More
Summary form only given. In the contribution, we show clear evidence that photonic crystals (PC) can be used in ultrasmall integrated optics to cascade two elements, in this case a cavity and a waveguide. We use as a basis PC a triangular array of holes of period a=220-260 nm etched through an AlGaAs planar waveguide, in which we define a hexagonal cavity of side h=7a (H7 cavity), and a guide with...Show More
The Ultrafast Photonics Collaboration (UPC) is a recently funded Interdisciplinary Research Collaboration with the aim of exploiting novel photonic technologies for ultrafast data communications networks. This paper discusses the nature of the collaboration and outlines the scientific programme.Show More
Summary form only given. We present results on the control of waveguided light around 1 /spl mu/m by two dimensional photonic bandgap (PBG) triangular lattices. The lattice consists of 0.8- /spl mu/m deep cylindrical holes etched through the waveguide with an air filling factor. To test PBG lattices we use the guided photoluminescence (PL) of InGaAs quantum wells embedded in a 0.24/spl mu/m-thick ...Show More

High-efficiency optoelectronic system for monitoring of antimicrobial resistance (AMR) in bacteria

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Antimicrobial resistance (AMR) is the ability of bacteria to become immune to antimicrobial treatments and it is going to become the main cause of death in the next decades. The diagnostic techniques usually used to define the most suitable antibiotics require long time delay and also provide a resolution that is not suitable to detect multibacterial diseases. Here, we propose an optoelectronic ap...Show More

High-efficiency optoelectronic system for monitoring of antimicrobial resistance (AMR) in bacteria

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We will demonstrate that Fourier space imaging technique of the light diffracted from a photonic crystal (PhC) device allows the direct measurement of important physical properties of the PhC such as dispersion curves, equi-frequency surfaces, group indices and the characterization of the device performances in a complex environment. Advance techniques based on size effect super-resolution or coup...Show More
Summary form only given. In planar microcavity light-emitting diodes (MCLEDs), light not extracted is lost to leaky modes and also, up to 40% or more, to unavoidable laterally propagating guided modes. Photonic crystals (PCs) located around the emitting area within a distance smaller than the absorption length may act as efficient scatterers that extract guided light outside the heterostructure pl...Show More
Photonic crystal waveguides have evolved from an academic curiosity to an area where practical applications are beginning to appear feasible. Waveguides consisting of a single line of missing holes ("W1") have become the benchmark to assess fabrication quality, and losses of order 10 dB/cm and below are now possible. We discuss fabrication aspects of such waveguides, made both by e-beam and by dee...Show More
We present what we believe is the highest efficiency and lowest threshold current density ever reported for semiconductor ring resonator lasers. Ring lasers are interesting components, e.g. for fiber-to-the-home systems, because they can readily be integrated and their very simple fabrication process, which is discussed and compared with other common approaches, does not require overgrowth or the ...
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Sharp resonance features are observed in the polarized reflectivity spectra of semiconductor photonic crystals fabricated by deep periodic patterning of AlGaAs surface waveguides. Both one- (1-D) and two-dimensional (2-D) lattices are studied by angular dependent reflectivity. By comparison with theory we show that the sharp features in reflectivity arise from resonant coupling of the external rad...Show More
We report on the measurement of the diffraction efficiency of two-dimensional photonic-bandgap lattices consisting of a triangular array of circular air holes etched in a semiconductor waveguide. We use the spontaneous emission of the material as an internal point source. Combined with previous reflectivity and transmission measurements, the diffraction data allow us to assess the total amount of ...Show More
Summary form only given.We show clear evidence that photonic crystals (PC) can be used in ultrasmall integrated optics to cascade two elements, in this case a cavity and a waveguide. We use as a basis PC a triangular array of holes of period a=220-260 nm etched through an AlGaAs planar waveguide, in which we define a hexagonal cavity of side h=7a (H7 cavity), and a guide with width varying from a ...Show More