This clinical report describes the nonsurgical treatment of a patient suffering from severe epistaxis associated with hereditary hemorrhagic telangiectasia (HHT). Unlike the permanent surgical closure of the nostrils, known as the Young procedure, this treatment option provides interim relief from nasal obstruction. It includes the use of cone beam computed tomography (CBCT) and computer-aided design (CAD) to create a patient-specific silicone nasal obturator without the need for an impression of the nasal cavity, thereby preventing irritation to the delicate nasal mucosa that could instigate epistaxis.
View Article and Find Full Text PDFA total rhinectomy may be part of the treatment of nasal malignancy and can cause severe facial disfigurement and unwanted psychological repercussions. A technique is described for fabricating a skin-colored interim nasal profile dressing for immediate fitting after surgery without the need for either preoperative or postoperative impressions. The technique avoids patient discomfort, and the initial emotional trauma of facial disfigurement may be avoided.
View Article and Find Full Text PDFReaction-based assays are commonly automated and miniaturized via flow analysis. However, aggressive reagents can affect or destroy even the chemically resistant manifold during long-term use. Using on-line solid-phase extraction (SPE) can eliminate this drawback and allow for high reproducibility and further advanced automation, as presented in this work.
View Article and Find Full Text PDFA flow-based method for the spectrophotometric determination of chromium (VI) in recreational waters with different salinities was developed. Chromium can occur in the environment in different oxidation states with different related physiological properties. With regard to chromium, the speciation is particularly important, as the hexavalent chromium is considered to be carcinogenic.
View Article and Find Full Text PDFA historical description of Wallace H. Coulter's invention and development of his companies' instrumentation for analysis of blood cells or particles has never been available, and too often, this void has been addressed by conjectural or promotional publications. A history thesis, based on the author's access to Coulter's personal papers and to files kept by his father, Joseph R.
View Article and Find Full Text PDFPhotonic integrated circuits (PICs) operating at cryogenic temperatures are fundamental building blocks required to achieve scalable quantum computing and cryogenic computing technologies. Silicon PICs have matured for room-temperature applications, but their cryogenic performance is limited by the absence of efficient low-temperature electro-optic modulation. Here we demonstrate electro-optic switching and modulation from room temperature down to 4 K by using the Pockels effect in integrated barium titanate (BaTiO) devices.
View Article and Find Full Text PDFWe trace the history of liquid core waveguides (LCWs, also called liquid core optical fibers) and the role Teflon AF (TAF) has played in their development. We show that, in any shot noise limited situation, the optimum signal-to-noise ratio (S/N) occurs at a path length of 1/α{ln[1 + 2(α/α)]}, approximately 2/α under most conditions, α and α being the light attenuation coefficient due to the analyte and the background, respectively. The analysis shows that LCW length should be selected depending on the applicable α value.
View Article and Find Full Text PDFThe ultimate goal of flow-based analytical techniques is to automate serial assays of a target analyte. However, when developing any reagent-based assay, the underlying chemistry has to be investigated and understood a step, which is almost always the most challenging component of the optimization effort. The difficulty lies in that almost all reagent-based assays were initially developed and optimized in a batch mode, with the aim to perform assays manually, within a time frame of up to 15 min, while flow injection techniques are designed to monitor concentration gradients at times prior to reaching chemical equilibria and while performing up to two assays per minute.
View Article and Find Full Text PDFThis study aimed to understand how people respond to different urban neighbourhoods. We explored whether participants' mental health and wellbeing, judgements of resident wealth, family SES and sentiments reflected in descriptions of place features predicted in situ sense of threat and trust. Forty-six student participants walked in groups through 2 urban neighbourhoods, separated by a park, in the North West of England, noting responses at pre-determined stops.
View Article and Find Full Text PDFMicroscale, continuous-profile, diffractive lenses have been fabricated and characterized. Lenses designed to operate at λ = 405 nm were created by focused ion beam milling of a glass substrate. The micro-structured profile was analysed by confocal microscopy and optical performance was quantified by measurements of the transmitted laser beam profile.
View Article and Find Full Text PDFWe demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single ^{87}Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics.
View Article and Find Full Text PDFScaling up linear-optics quantum computing will require multi-photon gates which are compact, phase-stable, exhibit excellent quantum interference, and have success heralded by the detection of ancillary photons. We investigate the design, fabrication and characterisation of the optimal known gate scheme which meets these requirements: the Knill controlled-Z gate, implemented in integrated laser-written waveguide arrays. We show device performance to be less sensitive to phase variations in the circuit than to small deviations in the coupler reflectivity, which are expected given the tolerance values of the fabrication method.
View Article and Find Full Text PDFLinear optics underpins fundamental tests of quantum mechanics and quantum technologies. We demonstrate a single reprogrammable optical circuit that is sufficient to implement all possible linear optical protocols up to the size of that circuit. Our six-mode universal system consists of a cascade of 15 Mach-Zehnder interferometers with 30 thermo-optic phase shifters integrated into a single photonic chip that is electrically and optically interfaced for arbitrary setting of all phase shifters, input of up to six photons, and their measurement with a 12-single-photon detector system.
View Article and Find Full Text PDFWe present a model for a Yb-doped distributed Bragg reflector (DBR) waveguide laser fabricated in phosphate glass using the femtosecond laser direct-write technique. The model gives emphasis to transverse integrals to investigate the energy distribution in a homogenously doped glass, which is an important feature of femtosecond laser inscribed waveguide lasers (WGLs). The model was validated with experiments comparing a DBR WGL and a fiber laser, and then used to study the influence of distributed rare earth dopants on the performance of such lasers.
View Article and Find Full Text PDFWe demonstrate three and four input multiports in a three dimensional glass platform, fabricated using the femtosecond laser direct-write technique. Hong-Ou-Mandel (HOM) interference is observed and a full quantum characterization is performed, obtaining two photon correlation matrices for all combinations of input and output ports. For the 3-port case, the quantum visibilities are accurately predicted solely from measurement of the classical coupling ratios.
View Article and Find Full Text PDFHighly localized fiber Bragg gratings can be inscribed point-by-point with focused ultrashort pulses. The transverse localization of the resonant grating causes strong coupling to cladding modes of high azimuthal and radial order. In this paper, we show how the reflected cladding modes can be fully analyzed, taking their vectorial nature, orientation and degeneracies into account.
View Article and Find Full Text PDFWe present an experimental and theoretical analysis of the influence of scattering losses on the net reflectivity of fiber Bragg gratings inscribed with a femtosecond laser and the point-by-point technique. We demonstrate that the ratio of the coupling strength coefficient to the scattering loss coefficient varies significantly with the inscribing laser pulse energy, and highlight that an optimal pulse-energy range exists for achieving high-reflectivity gratings. These results are critical for exploiting high power fiber laser opportunities based on point-by-point gratings.
View Article and Find Full Text PDFWe report the performance of a dual-wavelength waveguide laser based on a phase-modulated sampled-grating architecture fabricated using the femtosecond laser direct-write technique. The waveguide laser was written in Yb-doped phosphate glass and had a narrow linewidth (<10 pm), high signal-to-noise ratio (>60 dB), 5 mW output power per channel, and wavelength separation of 10 nm.
View Article and Find Full Text PDFWe report the generation of correlated photon pairs in the telecom C-band at room temperature from a dispersion-engineered silicon photonic crystal waveguide. The spontaneous four-wave mixing process producing the photon pairs is enhanced by slow-light propagation enabling an active device length of less than 100 μm. With a coincidence to accidental ratio of 12.
View Article and Find Full Text PDFWe demonstrate apodized fiber Bragg gratings (FBGs) inscribed with a point-by-point (PbP) technique. We tailor the grating phase and coupling amplitude through precise control over the longitudinal and transverse positions of each laser-inscribed modification. This method of apodization is facilitated by the highly localized, high-contrast modifications generated by focused IR femtosecond laser inscription.
View Article and Find Full Text PDFWe present a narrow-linewidth, linearly polarized neodymium-doped fiber laser that incorporates a point-by-point Bragg grating inscribed into the core of a single-polarization all-solid photonic bandgap fiber. The Bragg grating was written within a single-polarization wavelength band of the fiber; thus, the Bragg reflection was polarized. This all-fiber laser produced 7.
View Article and Find Full Text PDFWe demonstrate the fabrication by direct laser writing and the operation of a directional coupler containing Bragg gratings in each waveguide. We achieve high-precision control over the longitudinal shift between the gratings, which feature first-order Bragg resonance at telecommunication wavelengths. We observe fundamental differences between light transmission characteristics in couplers with unshifted and shifted gratings in agreement with theoretical predictions.
View Article and Find Full Text PDFThird-harmonic generation microscopy has been used to analyze the morphology of photonic structures created using the femtosecond laser direct-write technique. Three-dimensional waveguide arrays and waveguide-Bragg gratings written in fused-silica and doped phosphate glass were investigated. A sensorless adaptive-optical system was used to correct the optical aberrations occurring in the sample and microscope system, which had a lateral resolution of less than 500 nm.
View Article and Find Full Text PDFThe spectral characteristics of a fiber Bragg grating (FBG) with a transversely inhomogeneous refractive index profile, differs considerably from that of a transversely uniform one. Transmission spectra of inhomogeneous and asymmetric FBGs that have been inscribed with focused ultrashort pulses with the so-called point-by-point technique are investigated. The cladding mode resonances of such FBGs can span a full octave in the spectrum and are very pronounced (deeper than 20dB).
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