26 research outputs found
Room temperature mid-IR single photon spectral imaging
Spectral imaging and detection of mid-infrared (mid-IR) wavelengths are
emerging as an enabling technology of great technical and scientific interest;
primarily because important chemical compounds display unique and strong mid-IR
spectral fingerprints revealing valuable chemical information. While modern
Quantum cascade lasers have evolved as ideal coherent mid-IR excitation
sources, simple, low noise, room temperature detectors and imaging systems
still lag behind. We address this need presenting a novel, field-deployable,
upconversion system for sensitive, 2-D, mid-IR spectral imaging. Measured room
temperature dark noise is 0.2 photons/spatial element/second, which is a
billion times below the dark noise level of cryogenically cooled InSb cameras.
Single photon imaging and up to 200 x 100 spatial elements resolution is
obtained reaching record high continuous wave quantum efficiency of about 20 %
for polarized incoherent light at 3 \mum. The proposed method is relevant for
existing and new mid-IR applications like gas analysis and medical diagnostics
GaSbBi alloys and heterostructures: fabrication and properties
International audienceDilute bismuth (Bi) III-V alloys have recently attracted great attention, due to their properties of band-gap reduction and spin-orbit splitting. The incorporation of Bi into antimonide based III-V semiconductors is very attractive for the development of new optoelectronic devices working in the mid-infrared range (2-5 µm). However, due to its large size, Bi does not readily incorporate into III-V alloys and the epitaxy of III-V dilute bismides is thus very challenging. This book chapter presents the most recent developments in the epitaxy and characterization of GaSbBi alloys and heterostructures
Space Division Multiplexing in Optical Fibres
Optical communications technology has made enormous and steady progress for
several decades, providing the key resource in our increasingly
information-driven society and economy. Much of this progress has been in
finding innovative ways to increase the data carrying capacity of a single
optical fibre. In this search, researchers have explored (and close to
maximally exploited) every available degree of freedom, and even commercial
systems now utilize multiplexing in time, wavelength, polarization, and phase
to speed more information through the fibre infrastructure. Conspicuously, one
potentially enormous source of improvement has however been left untapped in
these systems: fibres can easily support hundreds of spatial modes, but today's
commercial systems (single-mode or multi-mode) make no attempt to use these as
parallel channels for independent signals.Comment: to appear in Nature Photonic
Changing Role of Harbour City
organized jointly by the Centre of Urban Planning and Environmental Management and Asia Pacific Research Institut
The role of transplanted Schwann cells in promoting regeneration of rat optic nerve (abstracts)
Current concern for ensuring the air-worthiness of the aging commercial air fleet has prompted the establishment of broad-agency programs to develop NDT technologies that address specific aging-aircraft issues.[1, 2] One of the crucial technological needs that has been identified is the development of rapid, quantitative systems for depot-level inspection of bonded aluminum lap joints on aircraft.[1–3] Research results for characterization of disbond and corrosion based on normal-incidence pulse-echo measurement geometries are showing promise, but are limited by the single-site nature of the measurement which requires manual or mechanical scanning to inspect an area. [4–7] One approach to developing efficient systems may be to transfer specific aspects of current medical imaging technology to the NDT arena. Ultrasonic medical imaging systems offer many desirable attributes for large scale inspection. They are portable, provide real-time imaging, and have integrated video tape recorder and printer capabilities available for documentation and post-inspection review. Furthermore, these systems are available at a relatively low cost (approximately 200,000) and can be optimized for use with metals with straight-forward modifications. As an example, ultrasonic phased-array and linear array imaging technology, which was first developed for use in the medical industry, has been successfully implemented for some NDT applications by other investigators. [8–10