Yb-doped phosphate double-cladding optical fiber laser for high-power applications

A Yb-doped phosphate glass double cladding optical fiber was prepared using a custom designed glass composition (P2O5 - Al2O3 - Li2O - B2O3 - BaO - PbO - La2O3) for high-power amplifier and laser applications. The preform drawing method was followed, with the preform being fabricated using the rotational casting technique. This technique, previously developed for tellurite, fluoride or chalcogenide glass preforms is reported for the first time using rare earth doped phosphate glasses. The main challenge was to design an adequate numerical aperture between first and second cladding while maintaining similar thermo-mechanical properties in view of the fiber drawing process. The preform used for the fiber drawing was produced by rod-in-tube technique at a rotation speed of 3000 rpm. The rotational casting technique allowed the manufacturing of an optical fiber featuring high quality interfaces between core and internal cladding and between the internal and external cladding, respectively. Loss attenuation was measured using the cut-back method and lasing was demonstrated at 1022 nm by core pumping with a fiber pigtailed laser diode at the wavelength of 976 n

Design, fabrication and characterization of a power amplifier based on special glasses for LIDAR sources

L'objectif de ce travail de recherche est l'étude, la réalisation et la caractérisation d'un amplificateur de puissance à base de verres spéciaux devant être inséré dans un dispositif laser impulsionnel à cohérence élevée opérant a la longueur d'onde de 1550 nm en configuration MOPA (Master Oscillator Power Amplifier). Il aura pour fonction d'amplifier le signal provenant d'un laser source afin de pouvoir le propager sur des distances élevées sans pour autant dégrader ses caractéristiques spectrales ou sa cohérence. Le dispositif ainsi obtenu sera utilisé comme source laser pour des systèmes LIDAR compact pouvant soit être embarqués à bord d'avions ou de voitures; soit être utilisés dans des stations météorologiques ou des aéroports. Un tel projet représente une innovation majeure dans le domaine des capteurs laser fonctionnant en espace libre. Il s'agit en effet de réaliser des dispositifs compacts qui n'existent pour l'instant pas aussi bien de façon commerciale que des les laboratoires de recherche.The objective of the present research is the study, fabrication and characterization of a power amplifier based on special glasses to be implemented as an embedded module inside a pulsed laser device with high coherence working at 1550 nm wavelength. The optical amplifier represents the second module of a laser in configuration MOPA (Master Oscillator Power Amplifier). The device must amplify the signal proceeding from a seed laser and allow the propagation of the signal at high distances while maintaining the spectral characteristics of the high coherent source. The device obtained with this approach will be employed as a source for a monitoring LIDAR system, which will be installed in train monitoring portals. The results can be extended to other applications as well, such as aeroplanes, meteorological stations or airports. The current research work is intended to contribute to the fabrication of compact devices that seems not be still available even in laboratories.Lo scopo della presente ricerca `e lo studio, la realizzazione e la caratter-izzazione di un amplificatore di potenza a base di vetri speciali da utiliz-zare come modulo da implementare all’interno di un dispositivo laser adimpulsi ad elevata coerenza operante alla lunghezza d’onda di 1550 nm.L’amplificatore ottico rappresenta il secondo modulo di un laser in configu-razione MOPA (Master Oscillator Power Amplifier): esso ha la funzione diamplificare il segnale proveniente da un laser “seed” e permette di propa-gare il suo segnale ad elevate distanze, mantenendo tuttavia le caratteris-tiche spettrali di elevata coerenza della sorgente. Il dispositivo cos`ı ottenutosar`a utilizzato come sorgente per un sistema LIDAR di rilevazione a bordodi aerei, autoveicoli e stazioni meteorologiche o aeroporti. Questi sistemisembrano non essere ancora disponibili neanche a livello dei laboratori diricerca

Design, fabrication and characterization of a optical power amplifier based on special glasses for LIDAR sources

The objective of the present research is the study, fabrication and characterization of a power amplifier based on special glasses to be implemented as an embedded module inside a pulsed laser device with high coherence working at 1550 nm wavelength. The optical amplifier represents the second module of a laser in configuration MOPA (Master Oscillator Power Amplifier). The device must amplify the signal proceeding from a seed laser and allow the propagation of the signal at high distances while maintaining the spectral characteristics of the high coherent source. The device obtained with this approach will be employed as a source for a monitoring LIDAR system, which will be installed in train monitoring portals. The results can be extended to other applications as well, such as aeroplanes, meteorological stations or airports. The current research work is intended to contribute to the fabrication of compact devices that seems not be still available even in laboratorie

Phosphate glasses for fiber laser applications

There is a technological and industrial need for compact and intense sources in particular for those operating in pulsed mode operation. These types of sources are required for micromachining and marking applications using 1 um wavelength sources and also for lidar applications at eye-safe wavelengths in the 1.5 micron wavelength region. Phosphate glasses are particularly well suited for developing such devices. As rare earth ion hosts, they allow for achieving doping concentrations up to 1021 ions/cm3 without clustering and photordarkening. Their high phonon energy is also well suited for efficient emissions from Nd3+ and Yb3+ at 1 micron and the 1.5 micron emission from Er3+, using standard pumping schemes either at 808 nm or 980 nm. Thanks to this efficiency together with their outstanding thermo-mechanical properties, phosphate glasses can sustain high beam intensity. We present and discuss the development of rare earth doped phosphate glasses and fibers for laser and optical amplification applications operating in the 1 micron and 1.5 wavelength regions. Three host glass compositions have been designed for fabricating double clad structured fibers where the core glass composition was doped either with Nd3+, Yb3+ or Yb3+/Er3+ according to the operation wavelength foreseen. Single mode fibers with losses of 3.5 dB/m have been developed allowing for basic implementation of fiber lasers and optical amplifiers

Phosphate Glass Fibers for Optical Amplifier Applications

We report on the development and characterization of phosphate glass optical fibers for laser and optical amplifier applications. We discuss preliminary results on the implementation of compact fiber lasers and optical amplifiers

Nd3+ Doped Phosphate Glass Optical Fibre Lasers

We report on the fabrication of three different phosphate glasses using a custom designed glass composition (P2O5 - Li2O - Al2O3 - B2O3 - BaO – PbO - MgO) with the aim to fabricate a Nd3+-doped double cladding optical fibre laser emitting at 1.06 μm. By changing properly the concentration and types of compounds present in our phosphate glass, the refractive indexes of the three glasses were adjusted in order to obtain an adequate numerical aperture between core and inner cladding, and between inner and outer cladding, while maintaining similar thermo-mechanical properties in view of the fibre drawing process. Physical and thermal properties of the glasses are presented and discussed. Spectroscopic properties of the core glass are described. In order to optimize Nd3+-doped fibre laser design, a numerical analysis of the lasers was performed and resulting design curves are presented. With the aim to test the feasibility of the double cladding optical fibre fabrication process and materials, a Yb3+/ Er3+ co-doped double cladding fibre based on the same glass host composition, was drawn and preliminary characterized

Fabrication and Characterization of a High-Gain Yb-Er Codoped Phosphate Glass Optical Amplifier

We present the fabrication and characterization of a short core pumped fiber amplifier made of Yb3+-Er3+ codoped phosphate glasses. The 27mm long amplifier provides a maximum internal gain of 10.7 dB for a signal of −30dBm at 1535nmwith a 479mW pump power operating at 975.6 nm. This leads to a gain of 4.0 dB/cm, which compares favorably to other recent works

3D Fusion Echocardiography Improves Transoeosphageal LV Assessment

Accurate left ventricular (LV) assessment by transoesophageal echocardiography (TOE) can be clinically important particularly in intensive care or intraoperative settings. Assessment from TOE views is limited by foreshortened imaging planes and mitral valve pathology. Transgastric short-axis (SAX) views allow better alignment but may be limited by patient tolerability or patient-related factors (e.g. post gastric surgery). Fusion of multiple 3D volume datasets is now technically possible and improves LV visualisation from transthoracic windows. We hypothesized that fusion of full 3D TOE volumes would improve LV image quality and allow SAX image reconstruction from the oesophagus with improved image quality vs. transgastric SAX views. © 2011 Springer-Verlag Berlin Heidelberg