1,150 research outputs found
Output polarization control of fiber DFB laser using injection locking
Author name used in this publication: W. H. ChungAuthor name used in this publication: H. Y. TamAuthor name used in this publication: P. K. A. WaiAuthor name used in this publication: M. S. Demokan2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Hemolysis and methemoglobinemia due to hepatitis E virus infection in patient with G6PD deficiency
published_or_final_versionSpringer Open Choice, 21 Feb 201
Simultaneous repolarization of two 10-Gb/s polarization-scrambled wavelength channels using a mutual-injection-locked laser diode
Author name used in this publication: W. H. ChungAuthor name used in this publication: P. K. A. WaiAuthor name used in this publication: H. Y. TamAuthor name used in this publication: M. S. Demokan2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Transmission Estimation at the Cram\'er-Rao Bound for Squeezed States of Light in the Presence of Loss and Imperfect Detection
Enhancing the precision of a measurement requires maximizing the information
that can be gained about the quantity of interest from probing a system. For
optical based measurements, such an enhancement can be achieved through two
approaches, increasing the number of photons used to interrogate the system and
using quantum states of light to increase the amount of quantum Fisher
information gained per photon. Here we consider the use of quantum states of
light with a large number of photons, namely the bright single-mode and
two-mode squeezed states, that take advantage of both of these approaches for
the problem of transmission estimation. We show that, in the limit of large
squeezing, these states approach the maximum possible quantum Fisher
information per photon for transmission estimation that is achieved with the
Fock state and the vacuum two-mode squeezed state. Since the bright states we
consider can be generated at much higher powers than the quantum states that
achieve the maximum quantum Fisher information per photon, they can achieve an
much higher absolute precision as quantified by the quantum Cram\'er-Rao bound.
We discuss the effects of losses external to the system on the precision of
transmission estimation and identify simple measurements techniques that can
saturate the quantum Cram\'er-Rao bound for the bright squeezed states even in
the presence of such external losses
Optical coherence tomography: an assessment of current training across all levels of seniority in 8 ophthalmic units in the united kingdom
BACKGROUND: Optical Coherence Tomography (OCT) is becoming an increasingly integral part of ophthalmological clinical practice. The accurate interpretation of OCT images is important both in terms of diagnosis and in directing subsequent management. The aim of this study was to determine the clinical competence in OCT image interpretation of ophthalmologists in different subspecialties and grades. METHODS: Eight OCT images demonstrating a single macular pathology and two normal scans were selected by case notes review. These ten images were shown to thirty doctors and 10 non-medical staff from eight units. They were asked to identify each lesion, the average thickness of the lesion, and the axis at which the OCT was taken. One point was awarded for each correct answer. RESULTS: The mean scores for the correct qualitative identification of the OCT lesion (with a maximum score of 10) for different grades of doctors and non-medical staff were as follows: medical retinal consultants (MRC), 9 (range, 8–10); vitreoretinal consultants (VRC), 7 (range, 6–9); non-retinal consultants (NRC), 4 (range, 2–6); vitreoretinal fellows (VRF), 4 (range, 3–7); specialist registrars (SpR), 3 (range, 2–5); senior house officers (SHO), 4 (range, 3–6); orthoptists, 1 (range, 0–1); ancillary staff, 2 (range, 0–3). CONCLUSION: A wide range in the ability to accurately interpret OCT images has been demonstrated. All doctors would thereby benefit from further training in the interpretation of OCT scans
All-optical bit-error monitoring system using cascaded inverted wavelength converter and optical NOR gate
Author name used in this publication: Demokan, M. S.Author name used in this publication: Wai, P. K. A.2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Quantum states of light produced by a high-gain optical parametric amplifier for use in quantum lithography
We present a theoretical analysis of the properties of an unseeded optical parametic amplifier (OPA) used as the source of entangled photons for applications in quantum lithography. We first study the dependence of the excitation rate of a two-photon absorber on the intensity of the light leaving the OPA. We find that the rate depends linearly on intensity only for output beams so weak that they contain fewer than one photon per mode. We also study the use of an N-photon absorber for arbitrary N as the recording medium to be used with such a light source. We find that the contrast of the interference pattern and the sharpness of the fringe maxima tend to increase with increasing values of N, but that the density of fringes and thus the limiting resolution does not increase with N. We conclude that the output of an unseeded OPA exciting an N-photon absorber provides an attractive system in which to perform quantum lithography
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