Long wavelength distributed feedback tapered quantum cascade lasers.

We present a study on distributed feedback tapered quantum cascade lasers emitting at 14 µm. The fabricated lasers with taper angles between 0° and 3° exhibited output powers scaling in accordance with the active zone volume increase. Reduced divergence angles as small as 4.

Quantum cascade lasers monolithically integrated on germanium.

Silicon (Si) photonics can have a major impact on the development of mid-IR photonics by leveraging on the reliable and high-volume fabrication technologies already developed for microelectronic integrated circuits. Germanium (Ge), already used in Si photonics, is a prime candidate to extend the operating wavelength of Group IV-based photonic integrated circuits beyond 8 µm, and potentially up to 15 µm. High performance quantum cascade lasers (QCLs) and interband cascade lasers grown on Si have been demonstrated, whereas no QCLs monolithically integrated on Ge have been reported yet.

Mid-infrared III-V semiconductor lasers epitaxially grown on Si substrates.

There is currently much activity toward the integration of mid-infrared semiconductor lasers on Si substrates for developing a variety of smart, compact, sensors based on Si-photonics integrated circuits. We review this rapidly-evolving research field, focusing on the epitaxial integration of antimonide lasers, the only technology covering the whole mid-to-far-infrared spectral range. We explain how a dedicated molecular-beam epitaxy strategy allows for achieving high-performance GaSb-based diode lasers, InAs/AlSb quantum cascade lasers, and InAs/GaInSb interband cascade lasers by direct growth on on-axis (001)Si substrates, whereas GaAs-on-Si or GaSb-on-Si layers grown by metal-organic vapor phase epitaxy in large capability epitaxy tools are suitable templates for antimonide laser overgrowth.

Optical power detector with broad spectral coverage, high detectivity, and large dynamic range.

Optical power measurements are needed in practically all technologies based on light. Here, we report a general-purpose optical power detector based on the photoacoustic effect. Optical power incident on the detector's black absorber produces an acoustic signal, which is further converted into an electrical signal using a silicon-cantilever pressure transducer.

Benzene sensing by Quartz Enhanced Photoacoustic Spectroscopy at 14.85 µm.

Benzene is a gas known to be highly pollutant for the environment, for the water and cancerogenic for humans. In this paper, we present a sensor based on Quartz Enhanced Photoacoustic Spectroscopy dedicated to benzene analysis. Exploiting the infrared emission of a 14.

Photoacoustic characteristics of carbon-based infrared absorbers.

We present an experimental comparison of photoacoustic responsivities of common highly absorbing carbon-based materials. The comparison was carried out with parameters relevant for photoacoustic power detectors and Fourier-transform infrared (FTIR) spectroscopy: we covered a broad wavelength range from the visible red to far infrared (633 nm to 25 μm) and the regime of low acoustic frequencies (< 1 kHz). The investigated materials include a candle soot-based coating, a black paint coating and two different carbon nanotube coatings.

Sub-ppb detection of benzene using cantilever-enhanced photoacoustic spectroscopy with a long-wavelength infrared quantum cascade laser.

We report a novel, to the best of our knowledge, photoacoustic spectrometer for trace gas sensing of benzene. A quantum cascade laser emitting at the wavelength 14.8 µm is used as the light source in the spectroscopic detection.

Off-beam QEPAS sensor using an 11-μm DFB-QCL with an optimized acoustic resonator.

An off-beam quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor was designed for ethylene detection using a distributed-feedback quantum cascade laser (QCL) operating in the mid-infrared around 11 μm. The acoustic microresonator configuration was experimentally optimized using an original open-cell photoacoustic setup with a MEMS microphone. Correction factors based on theoretical acoustic models were introduced in order to accurately describe the response of millimeter-sized acoustic resonators.

Half-disk laser: insight into the internal mode structure of laser resonators.

Usually electromagnetic modes inside a laser resonator are a matter of the theoretical studies. In a sense we manage "to have a look into a whispering gallery mode (WGM) resonator" and observe how the resonator modes arrange in reality. The picture occurs to be quite different from the commonly used Bessel modes in a disk resonator.

Quantum cascade lasers grown on silicon.

Technological platforms offering efficient integration of III-V semiconductor lasers with silicon electronics are eagerly awaited by industry. The availability of optoelectronic circuits combining III-V light sources with Si-based photonic and electronic components in a single chip will enable, in particular, the development of ultra-compact spectroscopic systems for mass scale applications. The first circuits of such type were fabricated using heterogeneous integration of semiconductor lasers by bonding the III-V chips onto silicon substrates.

Room temperature continuous wave operation of InAs-based quantum cascade lasers at 15 µm.

We report low threshold InAs/AlSb quantum cascade lasers emitting near 15 µm. The devices are based on a vertical design similar to those employed previously in far infrared InAs-based QCLs, whereas the doping level of the active core is considerably decreased. The lasers exhibit a threshold current density as low as 730 A/cm in pulsed mode at room temperature and can operate in this regime up to 410K.

[Prevalence of vitamin D deficiency in children aged 5-10 years in western Brittany].

Unlabelled: French guidelines do not recommend systematic supplementation of vitamin D in children aged 5-10 years old owing to the lack of data on vitamin D status in this age group. Our objective was to assess the prevalence of vitamin D deficiency in these children.

Methodology: Single-center, prospective, epidemiological study including 358 children aged 0-15 years.

Distributed feedback GaSb based laser diodes with buried grating: a new field of single-frequency sources from 2 to 3 µm for gas sensing applications.

We report on the growth, fabrication, experimental study and application in an absorption gas setup of distributed feed-back antimonide diode lasers with buried grating. First, half laser structures were grown by molecular beam epitaxy on GaSb substrates and stopped at the top of the waveguide. A second order Bragg grating was then defined by interferometric lithography on the top of the structure and dry etched by Reactive Ion Etching.

High temperature operation of far infrared (λ ≈20 µm) InAs/AlSb quantum cascade lasers with dielectric waveguide.

We demonstrate the high temperature operation, up to 80°C, of quantum cascade lasers emitting at a wavelength of 20 µm. The lasers are based on the InAs/AlSb materials and take benefit of a low loss plasmon-enhanced dielectric waveguide. The waveguide consists of doped InAs cladding layers and low-doped InAs spacers.

Characterization and prevalence of severe primary IGF1 deficiency in a large cohort of French children with short stature.

Objective: The prevalence of severe primary IGF1 deficiency (IGFD) is unclear. IGFD must be identified promptly as treatment with recombinant human IGF1 (rhIGF1) is now available. Our objective was to characterize and assess the prevalence of severe primary IGFD in a large cohort of patients evaluated for short stature at a pediatric endocrinology unit in France.

Unexpected high frequency of skeletal dysplasia in idiopathic short stature and small for gestational age patients.

Objective: To assess the prevalence of skeletal dysplasias (SDs) in patients with idiopathic short stature (ISS) or small for gestational age (SGA) status.

Setting: Rare Endocrine/Growth Diseases Center in Paris, France.

Design: A prospective study on consecutive patients with ISS and SGA enrolled from 2004 to 2009.

A novel FOXE1 mutation (R73S) in Bamforth-Lazarus syndrome causing increased thyroidal gene expression.

Background: Homozygous loss-of-function mutations in the FOXE1 gene have been reported in several patients with partial or complete Bamforth-Lazarus syndrome: congenital hypothyroidism (CH) with thyroid dysgenesis (usually athyreosis), cleft palate, spiky hair, with or without choanal atresia, and bifid epiglottis. Here, our objective was to evaluate potential functional consequences of a FOXE1 mutation in a patient with a similar clinical phenotype.

Methods: FOXE1 was sequenced in eight patients with thyroid dysgenesis and cleft palate.

Maternal phenylketonuria: low phenylalaninemia might increase the risk of intra uterine growth retardation.

Background: Malformations and mental retardation in the offspring of women with Phenylketonuria (PKU) can be prevented by maintaining maternal blood Phenylalanine (PHE) within a target range (120-300 μmol/L) through a PHE-restricted diet. In a former French study, a high and unexpected proportion of intra uterine growth retardation (IUGR) has been reported. Guidelines have been proposed to all French centres caring for maternal PKU since 2002.

Multiplex Ligation-dependent Probe Amplification improves the detection rate of NKX2.1 mutations in patients affected by brain-lung-thyroid syndrome.

Background: NKX2.1 mutations have been identified in patients displaying complete or partial brain-lung-thyroid syndrome, which can include benign hereditary chorea (BHC), hypothyroidism and/or lung disease.

Aims And Methods: We evaluated the recently developed Multiplex Ligation-dependent Probe Amplification (MLPA) method to assess the relative copy number of genes.

Mineralocorticoid receptor mutations and a severe recessive pseudohypoaldosteronism type 1.

Pseudohypoaldosteronism type 1 (PHA1) is a rare genetic disease of mineralocorticoid resistance characterized by salt wasting and failure to thrive in infancy. Here we describe the first case of a newborn with severe recessive PHA1 caused by two heterozygous mutations in NR3C2, gene coding for the mineralocorticoid receptor (MR). Independent segregation of the mutations occurred in the family, with p.

[Centralized preparation in the pharmacy of dilute solutions of ganciclovir: (Cymevan): work load change and economic potential].

The production of ganciclovir doses by a hospital pharmacy having the necessary facilities to reconstitute anticancer drugs would be of the utmost relevance regarding both protection of the nursing staff and therapeutic safety. As this activity is also economically worthwhile a large number of our colleagues would like to implement it. The aim of this work has was to take advantage of a 40 weeks production of ganciclovir dose by the pharmacy at Rangueil hospital in Toulouse so as to answer some of the questions raised by such a project.