RESUMEN
We report the fabrication of a 1.2 cm long cavity directly on a nanofiber using femtosecond laser ablation. The cavity modes with finesse values in the range of 200-400 can enable the "strong-coupling" regime of cavity QED, with high cooperativity of 10-20, for a single atom trapped 200 nm away from the fiber surface [Phys. Rev. A80, 053826 (2009)PLRAAN1050-294710.1103/PhysRevA.80.053826]. Such cavity modes can still maintain the transmission between 40%-60%, suggesting a one-pass intracavity transmission of 99.53%. Other cavity modes, which can enable cooperativity in the range of 3-10, show transmission over 60%-85% and are suitable for fiber-based single-photon sources and quantum nonlinear optics in the "Purcell" regime.
RESUMEN
We demonstrate the fabrication of photonic crystal (PhC) cavities on optical nanofibers using femtosecond laser ablation. PhC cavities with cavity lengths varying from 0.54 to 3.43 mm are fabricated by controlling the profile of the nanocrater array formed on the nanofiber. Such PhC cavities show high transmission of 87% for a finesse of 39. For higher finesse values from 150 to 500, the transmission can still be maintained at 20%-25%. Due to the strong confinement of the field and the efficient coupling to single-mode optical fibers, such nanofiber-based PhC cavities may become an interface between quantum and classical networks.
RESUMEN
Prolonged duration of the diabetes may affect the tiny blood vessels of the retina causing diabetic retinopathy. Routine eye screening of patients with diabetes helps to detect diabetic retinopathy at the early stage. It is very laborious and time-consuming for the doctors to go through many fundus images continuously. Therefore, decision support system for diabetic retinopathy detection can reduce the burden of the ophthalmologists. In this work, we have used discrete wavelet transform and support vector machine classifier for automated detection of normal and diabetic retinopathy classes. The wavelet-based decomposition was performed up to the second level, and eight energy features were extracted. Two energy features from the approximation coefficients of two levels and six energy values from the details in three orientations (horizontal, vertical and diagonal) were evaluated. These features were fed to the support vector machine classifier with various kernel functions (linear, radial basis function, polynomial of orders 2 and 3) to evaluate the highest classification accuracy. We obtained the highest average classification accuracy, sensitivity and specificity of more than 99% with support vector machine classifier (polynomial kernel of order 3) using three discrete wavelet transform features. We have also proposed an integrated index called Diabetic Retinopathy Risk Index using clinically significant wavelet energy features to identify normal and diabetic retinopathy classes using just one number. We believe that this (Diabetic Retinopathy Risk Index) can be used as an adjunct tool by the doctors during the eye screening to cross-check their diagnosis.
Asunto(s)
Retinopatía Diabética/diagnóstico , Técnicas de Diagnóstico Oftalmológico , Interpretación de Imagen Asistida por Computador/métodos , Análisis de Ondículas , Adulto , Retinopatía Diabética/patología , Fondo de Ojo , Humanos , Persona de Mediana Edad , Máquina de Vectores de SoporteRESUMEN
We demonstrate that thousands of periodic nano-craters are fabricated on a subwavelength-diameter tapered optical fiber, an optical nanofiber, by irradiating with just a single femtosecond laser pulse. A key aspect of the fabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. We also demonstrate that the periodic nano-crater array on the nanofiber shows polarization dependent fiber Bragg grating (FBG) characteristics. Such FBG structures on the nanofiber may act as a 1-D photonic crystal due to the strong transverse and longitudinal confinement of the field.
Asunto(s)
Cristalización/métodos , Tecnología de Fibra Óptica/instrumentación , Rayos Láser , Impresión Molecular/instrumentación , Nanopartículas/química , Nanopartículas/efectos de la radiación , Diseño de Equipo , Análisis de Falla de Equipo , Nanopartículas/ultraestructura , FotonesRESUMEN
Salivary fistula after a traumatic injury in the buccal region is not common. It is most commonly encountered in injuries involving the pre auricular region or soft tissues along the course of the parotid duct. It is more frequent in the parotid because its anatomical location is superficial; traumatic salivary fistulae of the other two major salivary glands are rare. This report presents an unusual case of a salivary fistula that occurred following trauma to the infraorbital region and drained into the inferior fornix of the left eye. A review of cases reported in the literature is presented. This is the only case of such a presentation the authors have found after a thorough search of the relevant English language literature.
Asunto(s)
Fístula/diagnóstico , Enfermedades del Aparato Lagrimal/diagnóstico , Enfermedades de las Parótidas/diagnóstico , Fístula de las Glándulas Salivales/diagnóstico , Adolescente , Párpados/lesiones , Traumatismos Faciales/cirugía , Femenino , Estudios de Seguimiento , Fracturas Conminutas/cirugía , Humanos , Fracturas Orbitales/cirugía , Complicaciones Posoperatorias/diagnósticoRESUMEN
We experimentally investigate the fluorescence photon emission characteristics for single q-dots by using optical nanofibers. We demonstrate that single q-dots can be deposited along an optical nanofiber systematically and reproducibly with a precision of 5 µm. For single q-dots on an optical nanofiber, we measure the fluorescence photon numbers coupled into the nanofiber and the normalized photon correlations, by varying the excitation laser intensity. We estimate the fluorescence photon coupling efficiency into the nanofiber guided modes.
Asunto(s)
Tecnología de Fibra Óptica/instrumentación , Dispositivos Ópticos , Fotometría/instrumentación , Puntos Cuánticos , Espectrometría de Fluorescencia/instrumentación , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Luz , FotonesRESUMEN
We present the experimental realization of nanofiber Bragg grating (NFBG) by drilling periodic nano-grooves on a subwavelength-diameter silica fiber using focused ion beam milling technique. Using such NFBG structures we have realized nanofiber cavity systems. The typical finesse of such nanofiber cavity is F â¼ 20 - 120 and the on-resonance transmission is â¼ 30 - 80%. Moreover the structural symmetry of such NFBGs results in polarization-selective modes in the nanofiber cavity. Due to the strong confinement of the field in the guided mode, such a nanofiber cavity can become a promising workbench for cavity QED.
RESUMEN
Vascular anomalies are amongst the most common congenital abnormalities observed in infants and children. Their occurrence in the head and neck region is a source of functional and aesthetic compromise. This article reviews the surgical management of 115 cases of vascular anomalies involving the head and neck area treated by the authors between 1998 and 2009. It discusses the diagnostic aids, treatment protocol and the results obtained. A new classification based on the anatomical location and depth of the lesion has been proposed. This allows guidelines for surgical ablation of the vascular lesions. The complications encountered are discussed. The use of external carotid artery control as opposed to pre-surgical embolization has proved effective and the technique is described. The location and extent of a vascular malformation should dictate the preoperative investigations, surgical procedure and subsequent outcome.
Asunto(s)
Cabeza/irrigación sanguínea , Cuello/irrigación sanguínea , Malformaciones Vasculares/cirugía , Adolescente , Adulto , Angiografía , Pérdida de Sangre Quirúrgica , Arteria Carótida Externa/cirugía , Niño , Preescolar , Protocolos Clínicos , Constricción , Embolización Terapéutica/métodos , Enfermedades del Nervio Facial/etiología , Femenino , Estudios de Seguimiento , Humanos , Complicaciones Intraoperatorias , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias , Hemorragia Posoperatoria/etiología , Recurrencia , Flujo Sanguíneo Regional/fisiología , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Malformaciones Vasculares/clasificación , Malformaciones Vasculares/diagnóstico , Adulto JovenRESUMEN
We show that the fluorescence emission spectrum of few atoms can be measured by using an optical nanofiber combined with the optical heterodyne and photon correlation spectroscopy. The observed fluorescence spectrum of the atoms near the nanofiber shows negligible effects of the atom-surface interaction and agrees well with the Mollow triplet spectrum of free-space atoms at high excitation intensity.
Asunto(s)
Nanofibras/química , Fotones , Espectrometría de Fluorescencia/instrumentación , Análisis Espectral/instrumentación , Diseño de EquipoRESUMEN
We experimentally demonstrate efficient coupling of atomic fluorescence to the guided mode of a subwavelength-diameter silica fiber, an optical nanofiber. We show that fluorescence of a very small number of atoms, around the nanofiber can be readily observed through a single-mode optical fiber. We also show that such a technique enables us to probe the van der Waals interaction between atoms and surface with high precision by observing the fluorescence excitation spectrum through the nanofiber.