Light emitting diodes and lasers for high-speed underwater optical communications

During the last decade, a lot of research has been carried-out around Underwater Wireless Optical Communications (UWOC) as they are considered as a promising technology for high data rate transmission in underwater environments

Structurally integrated transmitter beacon for underwater wireless optical communications in multiple ocean types

In this paper we describe a structurally integrated optical transmitter beacon concept that consists of a side-scattering fiber that can conform to solid surfaces, such as the outer surface of a submersible Remotely Operated Vehicle (ROV), suitable for convenient deployment in underwater applications. By coupling a modulated optical signal from a laser diode into the fiber, an omnidirectional "beacon" is achieved. We demonstrate coarse Wavelength Division Multiplexing (WDM), illustrating that these beacons can transmit optical wireless data through several attenuation lengths in turbid water at aggregate data rates of up to 20 Mb/s

Sensing properties of germanate and tellurite glass optical fibres

Strain and thermal sensitivities of germanate and tellurite glass fibres were measured using a fibre Fabry-Perot (FFP) interferometer and fibre Bragg gratings (FBG). The strain phase sensitivity for germanate and tellurite fibre were 5900×103 rad/m and 5600×103 rad/m respectively at a central wavelength of 1540nm using FFP interferometer, which is consistent with the value of 1.22pm/µepsilon obtained for a germanate fibre FBG. The Young's modulus for germanate and tellurite fibre were also measured to be 58GPa and 37GPa. The thermal responses of germanate fibre were examined as 24.71 and 16.80 pm/°C at 1540nm and 1033nm wavelength using the FBG

Fiber Bragg gratings inscribed using 800nm femtosecond laser and a phase mask in singleand multi-core mid-IR glass fibers

For the first time, Fiber Bragg grating (FBG) structures have been inscribed in single-core passive germanate and three-core passive and active tellurite glass fibers using 800 nm femtosecond (fs) laser and phase mask technique. With fs peak power intensity in the order of 10(11)W/cm(2), the FBG spectra with 2nd and 3rd order resonances at 1540 and 1033 nm in the germanate glass fiber and 2nd order resonances at approximately 1694 and approximately 1677 nm with strengths up to 14 dB in all three cores in the tellurite fiber were observed. Thermal responsivities of the FBGs made in these mid-IR glass fibers were characterized, showing average temperature responsivity approximately 20 pm/ degrees C. Strain responsivities of the FBGs in germanate glass fiber were measured to be 1.219 pm/microepsilon

Waveguide Tm:Lu2O3 ceramic laser fabricated by ultrafast laser inscription

Summary form only given. Ultrafast laser inscription (ULI) allows the fabrication of compact, highly-efficient and robust laser sources over a broad range of crystalline, ceramic and glass gain media. For instance, subsurface waveguides can be formed by the stress induced refractive index modification effect which takes place between two parallel modified regions referred to as “Type II” guiding [1]. Previously, a family of laser hosts known as sesquioxides, namely Lu2O3, Sc2O3 and LuScO3, have been shown to demonstrate efficient, high-power and tunable laser operation around the 2 μm region in both continuous-wave and pulsed regimes when doped with Tm3+ [2, 3]. Combining the Tm3+-doped sesquioxide material properties with the ULI waveguide laser geometry provides a means to produce compact, low-threshold and efficient laser sources near 2 μm with the potential for high pulse repetition rate ultrafast operation. Here we report, to the best of our knowledge, the first demonstration of a ceramic Tm:Lu2O3 waveguide laser source fabricated by ULI.Postprin

Waveguide Tm:Lu2O3 ceramic laser fabricated by ultrafast laser inscription

Summary form only given. Ultrafast laser inscription (ULI) allows the fabrication of compact, highly-efficient and robust laser sources over a broad range of crystalline, ceramic and glass gain media. For instance, subsurface waveguides can be formed by the stress induced refractive index modification effect which takes place between two parallel modified regions referred to as “Type II” guiding [1]. Previously, a family of laser hosts known as sesquioxides, namely Lu2O3, Sc2O3 and LuScO3, have been shown to demonstrate efficient, high-power and tunable laser operation around the 2 μm region in both continuous-wave and pulsed regimes when doped with Tm3+ [2, 3]. Combining the Tm3+-doped sesquioxide material properties with the ULI waveguide laser geometry provides a means to produce compact, low-threshold and efficient laser sources near 2 μm with the potential for high pulse repetition rate ultrafast operation. Here we report, to the best of our knowledge, the first demonstration of a ceramic Tm:Lu2O3 waveguide laser source fabricated by ULI.Postprin

The differential translation capabilities of the human DHFR2 gene indicates a developmental and tissue specific endogenous protein of low abundance.

A functional role has been ascribed to the human Dihydrofolate reductase 2 (DHFR2) gene based on the enzymatic activity of recombinant versions of the predicted translated protein. However, the in vivo function is still unclear. The high amino acid sequence identity (92%) between DHFR2 and its parental homologue, DHFR, makes analysis of the endogenous protein challenging. This paper describes a targeted mass spectrometry proteomics approach in several human cell lines and tissue types to identify DHFR2 specific peptides as evidence of its translation. We show definitive evidence that the dihydrofolate reductase activity in the mitochondria is in fact mediated by DHFR, and not DHFR2. Analysis of Ribo-seq data and an experimental assessment of ribosome association using a sucrose cushion, showed that the two main Ensembl annotated mRNA isoforms of DHFR2, 201 and 202, show differential association with the ribosome. This indicates a functional role at both the RNA and protein level. However, we were unable to detect DHFR2 protein at a detectable level in most cell types examined despite various RNA isoforms of DHFR2 being relatively abundant. We did detect a DHFR2 specific peptide in embryonic heart, indicating that the protein may have a specific role during embryogenesis. We propose that the main functionality of the DHFR2 gene in adult cells is likely to arise at the RNA level

Linear and nonlinear optics of chalcogenide bulk glasses and fibre for ultrafast all-optical switching

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