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We report a novel OFDM-transmitter operating in the emerging 2µm waveband. Sub-FEC limit transmission of a 32QAM signal over 500m of both solid and hollow-core fiber was achieved and the generation of 30Gbits 64QAM demonstrated.

X-ray computational tomography is demonstrated as a powerful non-destructive tool to image the internal structure of a hollow core photonic band-gap fibre and its preforms. The technique is applied to measure the deformation within a splice with unprecedented detail.

We present a new S2-based technique with potential for near real-time (1s) characterization of the modal-content of multimode fibers. We also demonstrate the identification and removal of measurement artifacts originating from reflections from optical components.

Hollow core photonic bandgap fibres (HC-PBGFs) are emerging as contenders in the race to identify the best solution for next-generation high capacity transmission systems, owing to their low nonlinearity, ultimate-low signal latency, an ideal match to thulium-doped fibre amplifiers and to the promise to deliver ultralow loss, potentially comparable or even below the level of state-of-the-art single mode fibres. Recently, substantial progress in the development of HC-PBGFs has been reported; however, for these fibres to stand a realistic chance of competing with solid transmission fibres, the key challenges of loss reduction over a sufficiently wide transmission bandwidth, as well as the ability to produce fibres in multi-hundred kilometre lengths must be addressed. A predicted route to reduce loss is by increasing the core size, e.g. from 19-cell to 37-cell. In this work we review recent progress in the development of HC-PBGFs based on a 37-cell core geometry, including the realization of fibres with low loss, wide bandwidth, low modal crosstalk and low bending loss, which have paved the way to data transmission experiments using mode division multiplexing. We also investigate the issue of longitudinal uniformity in HC-PBGFs and report a systematic study of defects observed in these fibres - a first step towards their removal and thus towards the demonstration of multi-kilometre lengths of defect free fibres.

We describe low loss (50dB/km at 3.3µm) and low bend sensitivity mid-IR hollow core-photonic bandgap fiber. Gas sensing applications are highlighted by a methane spectrum recorded in our fiber.

We present sub-ppm sensitivity, broadband gas absorption measurements using improved hollow-core photonic-bandgap fibers with low loss in the range 3-3.6 μm. The sensitivity levels, unprecedented for a fiber-based sensor system, were achieved by addressing the strong mid-IR vibrational bands through use of a high-intensity supercontinuum source and by exploiting long interaction lengths in the HC-PBGFs. We measured mixtures of methane (1034 ppm) and ethane (50.4 ppm) and attained 7 and 0.9 ppm sensitivities for 0.925 and 5.69 m long HC-PBGF samples, respectively, from high-resolution (0.2 nm) spectra. Significant scope for further sensitivity improvement exists through use of longer fibers in combination with more sophisticated sensing schemes.

Hollow-core photonic-bandgap fiber, fabricated from high-purity synthetic silica, with a wide operating bandwidth between 3.1 and 3.7µm, is reported. A minimum attenuation of 0.13dB/m is achieved through a 19-cell core design with a thin core wall surround. The loss is reduced further to 0.05dB/m following a purging process to remove hydrogen chloride gas from the fiber - representing more than an order of magnitude loss reduction as compared to previously reported bandgap-guiding fibers operating in the mid-infrared. The fiber also offers a low bend sensitivity of

To improve yield in fabricated HC-PBGFs we have studied morphology and longitudinal evolution of occasional, undesired defects causing localized loss. The short spatial and temporal duration of the defects seems indicative of residual preform contaminations.

We present a method to reconstruct the cross-sectional profile of fabricated hollow-core photonic bandgap fibers from SEM images. For the first time, numerical simulations show a good agreement with measured loss and surface mode position.

First experimental wavelength scaling in 19-cell core HC-PBGF indicates that the minimum loss waveband occurs at longer wavelengths than previously predicted. Record low loss (2.5dB/km) fibers operating around 2µm and gas-purging experiments are also reported.

We review recent progress towards improving the transmission properties of hollowcore photonic band gap fibres including advances made in understanding the key issues limiting minimum loss and bandwidth in current fabricated structures.

We review our recent progress in developing hollow core photonic bandgap fibers for high capacity data transmission. Novel numerical and characterization tools developed to improve fiber performance and yield will be discussed.

We review the capacity records achieved using mode-division multiplexing in few-mode fiber and hollow-core photonic bandgap fibers. Currently the MDM-capacity record for both fiber types is 73.7 Tb/s, whereas per wavelength 960 Gb/s is achieved.

The longest coherent transmission distance of 0.95km, and highest distance×bandwidth product 19cell hollow-core photonic bandgap fiber (HC-PBGF) are demonstrated, indicating the potential for longer distance HC-PBGF high capacity coherent transmission applications.

We review our fabrication of low loss (50dB/km at 3.3μm) and low bend sensitivity HC-PBGFs for mid-IR operation. Gas sensing applications are highlighted by a high resolution methane spectrum recorded in 1.26m of gas-filled fiber.

A method to track the evolution of a microstructured fibre, from initial preform to final fibre geometry, is presented. Up scaling to longer lengths, new structure development and effects of material parameters can all be explored with this model.

The origins of South America's domestic alpaca and llama remain controversial due to hybridization, near extirpation during the Spanish conquest and difficulties in archaeological interpretation. Traditionally, the ancestry of both forms is attributed to the guanaco, while the vicuña is assumed never to have been domesticated. Recent research has, however, linked the alpaca to the vicuña, dating domestication to 6000-7000 years before present in the Peruvian Andes. Here, we examine in detail the genetic relationships between the South American camelids in order to determine the origins of the domestic forms, using mitochondrial (mt) and microsatellite DNA. MtDNA analysis places 80% of llama and alpaca sequences in the guanaco lineage, with those possessing vicuña mtDNA being nearly all alpaca or alpaca-vicuña hybrids. We also examined four microsatellites in wild known-provenance vicuña and guanaco, including two loci with non-overlapping allele size ranges in the wild species. In contrast to the mtDNA, these markers show high genetic similarity between alpaca and vicuña, and between llama and guanaco, although bidirectional hybridization is also revealed. Finally, combined marker analysis on a subset of samples confirms the microsatellite interpretation and suggests that the alpaca is descended from the vicuña, and should be reclassified as Vicugna pacos. This result has major implications for the future management of wild and domestic camelids in South America.

Hollow-Core Photonic-Bandgap Fibres (HC-PBGFs) offer several distinct advantages over conventional fibres, such as low latency and radiation hardness; properties that make HC-PBGFs interesting for the high energy physics community. This contribution presents the results from a gamma irradiation test carried out using a new type of HC-PBGF that combines sufficiently low attenuation over distances that are compatible with high energy physics applications together with a transmission bandwidth that covers the 1550nm region. The radiation induced attenuation of the HC-PBGF was two orders of magnitude lower than that of a conventional fibre during a 67.5 hour exposure to gamma-rays, resulting in a radiation-induced attenuation of only 2.1dB/km at an accumulated dose of 940kGy.

We investigate the propagation, growth, and decay of fast magnetosonic waves in the Earth's magnetosphere which are believed to contribute to proton heating up to energies of a few hundred eV near the magnetic equator. We construct a model of the proton and electron distribution functions from spacecraft data and use the HOTRAY code to calculate the path-integrated growth and decay of the waves over a range of L shells from L = 2 to L = 7. Instability calculations show that the waves are excited at very large angles of propagation with respect to the magnetic field, ψ ≈ 89°, at the harmonics of the proton gyrofrequency ΩH+ up to the lower hybrid resonance frequency ωLHR by a proton ring distribution at energies of the order of 10 keV. As a “rule of thumb”, we find that growth is possible for ω > 30ΩH+ when the ring velocity exceeds the Alfven speed vR > vA, and for ω 2vA. For propagation in the meridian plane, waves generated just outside the plasmapause grow with large amplification as they propagate away from the Earth but eventually lose energy to plasma sheet electrons at energies of a few keV by Landau damping. The waves grow to large amplification at frequencies just below ωLHR. For inward propagation we find that waves generated just outside the plasmapause can propagate to L ≈ 2 with very little attenuation, suggesting that waves observed well inside the plasmasphere could originate from a source region just outside the plasmapause. Strong wave growth only occurs for large angles of propagation, and thus the waves are confined to within a few degrees of the magnetic equator. Waves generated near geostationary orbit and which propagate toward the Earth are absorbed by Doppler-shifted cyclotron resonance when they propagate into a region where vR < vA. Cyclotron resonant absorption causes pitch angle scattering and heating transverse to the ambient magnetic field. The amount of absorption, and hence transverse proton heating, increases significantly as the thermal proton temperature is increased up to 100 eV, suggesting a feedback process. Ray tracing shows that transverse heating of the thermal proton distribution is most likely to occur just outside the plasmapause where vA is large. Since proton ring distributions are formed during magnetic storms at ring current energies, we suggest that fast magnetosonic waves provide an additional energy loss process for ring current decay.

An oligodeoxynucleotide has been synthesized, which mimics an ``antigene'' oligonucleotide with a polypyrimidic stretch on its 5′ side and is protected on its 3′ side against nucelases by a naturally forming and very stable hairpin, 5′GCGAAGC3′. The in vitro degradation of the resulting oligonucleotide d(5′TTCTCGCGAAGC3′) has already been studied by fluorescence resonance energy transfer (FRET) (Refregiers et al. 1996, J Biomol Struct Dyn 14: 365 – 371). The technique required the grafting of fluorophores at both ends of the oligonucleotide. In the present work we have compared the hairpin formed in the presence and in the absence of such fluorophores. This was achieved by the study of the Raman spectra (excitation at 257 nm) of the oligodeoxynucleotides H, which forms the hairpin (5′TTCTCGCGAAGC3′), and a con-trol C (5′TTCTCCGGAAGC3′) which is unable to form the hairpin. Resonance Raman spectroscopy with 257 nm excitation greatly favors the resonance of purines and therefore the study of the 3′ part of the oligonucleotides. The difference spectrum obtained from resonance Raman spectra of C and H showed marker peaks specific for hairpin formation. The search for these marker peaks in difference spectra involving the Raman spectrum of H labeled by fluorophores and either C or H proved that the fluorophores do not modify the structure of the hairpin but only the vibrations of the two terminal bases on which the fluorophores are grafted. The use of such labeling is then justified in order to allow oligonucleotides protected by a hairpin on their 3′ side to be studied by fluorescence spectroscopy.

Resonance Raman spectra excited at 257 nm are reported for the complexes of the Nickel, Cobalt and Zinc derivatives of Tetrakis(4-N-methylpyridyl)porphine with poly(dA.dT)2, poly(dA)poly(dT), poly(dG.dC)2 and poly(dG).poly(dC). These spectra are interpreted as evidence of multiple outside binding modes with poly(dA).poly(dT), and of evidence for an outside binding mode with Poly(dG.dC)2. Some results obtained for the zinc derivative with poly(dA).poly(dT) suggest a binding mode peculiar to this derivative.

The first demonstration of a hollow core photonic bandgap fiber (HC-PBGF) suitable for high-rate data transmission in the 2 µm waveband is presented. The fiber has a record low loss for this wavelength region (4.5 dB/km at 1980 nm) and a >150 nm wide surface-mode-free transmission window at the center of the bandgap. Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups. Through the use of a custom built Thulium doped fiber amplifier with gain bandwidth closely matched to the fiber's low loss window, error-free 8 Gbit/s transmission in an optically amplified data channel at 2008nm over 290m of 19 cell HC-PBGF is reported.

We examine mid- to late Holocene centennial-scale climate variability in Ireland using proxy data from peatlands, lakes and a speleothem. A high degree of between-record variability is apparent in the proxy data and significant chronological uncertainties are present. However, tephra layers provide a robust tool for correlation and improve the chronological precision of the records. Although we can find no statistically significant coherence in the dataset as a whole, a selection of high-quality peatland water table reconstructions co-vary more than would be expected by chance alone. A locally weighted regression model with bootstrapping can be used to construct a ‘best-estimate’ palaeoclimatic reconstruction from these datasets. Visual comparison and cross-wavelet analysis of peatland water table compilations from Ireland and Northern Britain shows that there are some periods of coherence between these records. Some terrestrial palaeoclimatic changes in Ireland appear to coincide with changes in the North Atlantic thermohaline circulation and solar activity. However, these relationships are inconsistent and may be obscured by chronological uncertainties. We conclude by suggesting an agenda for future Holocene climate research in Ireland.

International audience; Gas-filled hollow optical fiber references based on the P(13) transition of the ν1+ν3 band of C122H2 promise portability with moderate accuracy and stability. Previous realizations are corrected (

We formulate a simple model based on mass conservation to accurately predict the structural parameters of hollow-core photonic bandgap fibers from knowledge of the second stage preforms from which they are drawn. We show that combining this model with precalculated property maps can allow real-time prediction of the optical properties of manufactured fibers.

We report fabrication of the first low-loss, broadband 37-cell photonic bandgap fiber. Exploiting absence of surface modes and low cross-talk in the fiber we demonstrate mode division multiplexing over three modes with record transmission capacity.

Hollow core-photonic bandgap fiber, operating in the spectral region between 3 and 4 µm, is reported. Order of magnitude loss reduction is demonstrated (0.13dB/m) compared to previously reported fibers, combined with very low bend sensitivity.

We review our recent progress in the fabrication, characterization, modeling and splicing of wide transmission bandwidth hollow core photonic bandgap fibers and discuss their modal properties and potential for data transmission.

We review our recent progress in the fabrication, characterization, modeling and splicing of wide transmission bandwidth hollow core photonic bandgap fibers and discuss their modal properties and potential for data transmission.

Photonic bandgap fibers (PBGF) potentially offer a very substantial increase of capacity per fiber over solid core fibers. We review transmission experiments using PBGF and their viability for next-generation transmissions systems.

Validation of novel splicing strategy enabling integration of hollow-core photonic band gap fiber with both itself and conventional SMF is presented. Self-splices are robust and low loss (0.16dB). Penalty-free 40Gbit/s data transmission is demonstrated in 1km arrangement of spliced HC-PBGF.

Summary Interactions of the antiretroviral hypericin molecule with polynucleotides, i.e. poly(dG-dC), poly(dA-dT), poly(rG) and poly(rC), have been studied in aqueous solutions by resonance Raman spectroscopy, using an UV excitation wavelength which induces a specific resonance enhancement of spectral band intensities corresponding to proper nucleic base modes of vibration. It is shown that : i) hypericin selectively interacts with the N7 sites of purines, ii) the strength of interaction depends on the polymer structure, and : iii) interaction with guanine is stronger than with adenine molecules.

Comparison of pre-conquest and contemporary Andean llama and alpaca phenotypes suggests that a breakdown in specialized breeding took place after European contact which led to the disappearance of fine fibre producing alpaca and llama breeds. The causes of this loss ultimately lie in the decimation of native Andean herds and herders during the Spanish conquest. The heterogeneous characteristics of today's animals can be attributed to extensive hybridization and a possible genetic bottle neck during the 16th century.

We present a fast implementation of the spatial and spectral imaging ( $\text{S}^{2})$ technique for a modal analysis of multimode optical fibers. It utilizes a continuously scanning tunable laser source with an InGaAs camera operating at 500 Hz along with inline data processing to increase the measurement repetition rate, by reducing the run up/run down time between two successive scans (about 27 times faster as compared with the previous state of the art). This allows real-time mode content monitoring of a multimode fiber. We illustrate the potential of this tool by collecting an 110 000 wavelength $\text{S}^{2}$ spectrogram of a five mode-group fiber in minutes, and tracking, in real-time, the four LP11 modes of the same fiber as the launch polarization is rotated.

Actualmente es posible determinar el estatus de especies silvestres mediante el analisis de ADN extraido de muestras no invasivas como las heces. Aunque dichos analisis suelen ser dificultosos debido principalmente a la composicion y conservacion de las heces, se ha demostrado en muchas especies que con el desarrollo de metodos adecuados de extraccion es posible maximizar la fiabilidad y eficacia de este procedimiento. Por tanto, el objetivo del presente estudio fue optimizar un metodo de extraccion de ADN de heces de vicuna Vicugna vicugna mensalis, especie clasificada como casi amenazada en el Peru, con la finalidad de obtener ADN de suficiente calidad para analisis moleculares. Se recolectaron 51 muestras de heces durante los meses de agosto y septiembre de 2008 en dos comunidades vicuneras ubicadas a mas de 4600 msnm en los departamentos de Junin y Moquegua. Luego de observar la defecacion, las muestras fueron recolectadas en forma inmediata, conservadas en etanol y transportadas al laboratorio para la extraccion del ADN. El kit comercial QIAamp® DNA Stool Mini Kit (QIAGEN) fue modificado para incluir un vigoroso y extenso proceso de agitacion y los resultados fueron comparados con dos protocolos comunmente utilizados: fenol/cloroformo/alcohol isoamilico y el mismo kit QIAGEN. La cantidad del ADN extraido fue observado en electroforesis horizontal en geles de agarosa, y la calidad evaluada mediante la amplificacion y visualizacion de los tamanos esperados de los microsatelites YWLL46 y LCA19. Aunque se logro extraer ADN con los tres metodos, solamente el metodo modificado permitio obtener ADN de suficiente calidad para ser utilizado en pruebas moleculares. Palabras clave: extraccion de ADN, heces, vicuna

Se reporta el desarrollo y optimizaciones de tecnicas moleculares (PCR simple, mul- tiple y semi-anidada) para determinar el sexo de camelidos sudamericanos (CSA) amplifi- cando la secuencia del gen Zinc Finger Protein (ZF). La tecnica utilizo ADN obtenido de 28 muestras de sangre de alpacas, llamas y vicunas, 20 muestras de heces de vicunas y guanacos conservadas en etanol al 96%, y 22 embriones de alpaca colectados entre 72 y 96 horas postmonta y preservados en etanol. Las muestras de ADN de sangre y heces fueron extraidas usando kits comerciales, y las de embriones aplicando tres metodos (ebullicion, proteinasa K y fenol-cloroformo). Una vez optimizada la PCR simple para la deteccion de los genes ZFY y ZFX, se implemento la PCR multiple para ADN de sangre y heces y la PCR semi-anidada para ADN de embriones. La tecnica de PCR multiple deter- mino el sexo correctamente en el 100% de las muestras de ADN sanguineo, en el 87.5% de muestras de ADN de heces colectadas en 2008 y en el 50% de las muestras de ADN de heces colectadas en 2004 y preservadas durante cuatro anos antes del analisis. La prue- ba de PCR semi-anidada, sin embargo, no pudo ser optimizada

International audience; This paper describes the development and evaluation of compact and simple acetylene-stabilized diode laser frequency standards in the 1.55 μm spectral region. A variety of spectroscopic configurations have been investigated, using bulk acetylene cells and an acetylene-filled hollow core photonic crystal fiber. Frequency stability and reproducibility data, obtained by heterodyne beat frequency comparison with cavity-enhanced standards, will be presented for sources including a distributed feedback diode laser and a digital supermode distributed Bragg reflector diode laser.

We report on progress in different hollow core photonic crystal fiber (HC-PCF) design and fabrication for atomic vapor based applications. We have fabricated a Photonic bandgap (PBG) guiding HC-PCF with a record loss of 107dB/km at 785nm in this class of fiber. A double photonic bandgap (DPBG) guiding HC-PCF with guidance bands centred at 780nm and 1064nm is reported. A 7-cell 3-ring Kagome HC-PCF with hypocycloid core is reported, the optical loss at 780nm has been reduced to 70dB/km which to the best of our knowledge is the lowest optical loss reported at this wavelength using HC-PCF. Details on experimental loading of alkali metal vapours using a far off red detuned laser are reported. This optical loading has been shown to decrease the necessary loading time for Rb into the hollow core of a fiber. The quantity of Rb within the fiber core has been enhanced by a maximum of 14% through this loading procedure.

We study the rich multimode content of an ultra-low loss hollow core photonic bandgap fiber using two complementary techniques which allow us to investigate both short and long propagation distances. Several distinct vector modes are clearly identified, with evidence of low intermodal coupling and distributed scattering.

The first demonstration of a hollow core photonic bandgap fiber suitable for high-rate data transmission at 2µm is presented. Using a custom built Thulium doped fiber amplifier, error-free 8Gbit/s transmission in an optically amplified data channel at 2008nm is reported for the first time.

We discuss the potential advantages that hollow core photonic bandgap fibers may ultimately have over conventional all solid fibers and review the state-of-the-art, fundamental physical limits and the many technological challenges to be overcome.

19-cell defect HC-PBGF is fabricated with record low loss (5.2 dB/km) at 2 μm. Gas absorption lines present in the fiber post-fabrication are quantified with initial conclusions on the origin and removal of relevant species.

We report transmission of 37 x 40 Gbit/s C-band channels over 250 m of hollow core band gap fibre, at 99.7% the speed of light in vacuum. BER penalty below 1 dB as compared to back-to-back was measured across the C-band.

A photonic microcell (PMC) is a length of gas-filled hollow core-photonic crystal fiber (HC-PCF) which is hermetically sealed at both ends by splicing to standard single mode fiber. We describe advances in the fabrication technique of PMCs which enable large core Kagome-lattice HC-PCFs to be integrated into PMC form. The modified fabrication technique uses fiber-tapering to accommodate the large dimensions of the fiber and enables low loss splices with single mode fiber by reducing mode field mismatch. Splice losses as low as 0.6 dB are achieved between 1-cell defect Kagome HC-PCF and single mode fiber. Relative to the previously reported PMCs, which were based on photonic bandgap HC-PCF, the present Kagome HC-PCF based PMC provides broad optical transmission, surface mode-free guidance and larger core at the cost of slightly increased fiber attenuation (~0.2 dB/m). Therefore, the integration of this fiber into PMC form opens up new applications for PMC-based devices. The advantage of the large core dimensions and surface mode free guidance for quantum optics in gas-filled HC-PCF are demonstrated by generation of narrow sub-Doppler features in an acetylenefilled large core PMC.

International audience; We demonstrate for the first time an optically pumped gas laser based on population inversion using a hollow core photonic crystal fiber (HC-PCF). The HC-PCF filled with 12C2H2 gas is pumped with ~5 ns pulses at 1.52 μm and lases at 3.12 μm and 3.16 μm in the mid-infrared spectral region. The maximum measured laser pulse energy of ~6 nJ was obtained at a gas pressure of 7 torr with a fiber with 20 dB/m loss near the lasing wavelengths. While the measured slope efficiencies of this prototype did not exceed a few percent due mainly to linear losses of the fiber at the laser wavelengths, 25% slope efficiency and pulse energies of a few mJ are the predicted limits of this laser. Simulations of the laser’s behavior agree qualitatively with experimental observations.

A continuous-wave diode laser is stabilized to a near-infrared acetylene transition inside a sealed kagome photonic crystal fiber. Stability and absolute frequency are measured with a frequency comb, and polarization sensitivity is observed.

Alpha-track detectors made of CR-39 plastic were successfully tested in monitoring surface alpha contamination in decontamination and decommissioning. The alpha registration efficiency was about 70%. At 3.7 Bq cm -2 a 10:1 signal-to-noise response was obtained after a 100-min exposure. The alpha-track detector maps small-scale spacial variability of alpha contamination that conventional survey meters cannot. The detector recognizes hot particles. Small-sized detectors are deployable in difficult-to-access locations such as cracks or under tightly fitting equipment where dirt resists easy removal

A CW fiber laser is stabilized to near-infrared transitions of 12C2H2 inside kagome fibers and characterized with a frequency comb. ±10 kHz accuracy is achieved, and performance in sealed photonics microcells is explored.

We report on a novel means which lifts the restriction of the limited optical bandwidth of photonic bandgap hollow-core photonic crystal fiber on generating high order stimulated Raman scattering in gaseous media. This is based on H(2)-filled tapered HC-PCF in which the taper slope is matched with the effective length of Raman process. Raman orders outside the input-bandwidth of the HC-PCF are observed with more than 80% quantum-conversion using a compact, low-power 1064 nm microchip laser. The technique opens prospects for efficient sources in spectral regions that are poorly covered by currently existing lasers such as mid-IR.

We report on kagomé-lattice photonic microcells with low losses, large outer diameters, and large cores. The large (40-70microm) cores are accommodated by tapering the fibers and splicing the reduced ends to a single-mode fiber. We demonstrate the repeatability of this process and obtain splice losses of 0.6dB by optimizing the taper transition length. Narrow electromagnetically induced transparencies and saturable absorption are demonstrated in an acetylene-filled photonic microcell.