We present some of our research activities dedicated to doped silica-based optical fibers, aiming at understanding the spectral properties of luminescent ions, such as rare-earth and transition metal elements. The influence of the local environment on dopants is extensively studied: energy transfer mechanisms between rare-earth ions, control of the valence state of Chromium ions, effect of the ...

Modeling the random fiber distribution of a fiber-reinforced composite is of great importance for studying the progressive failure behavior of the material on the micro scale. In this paper, we develop a new algorithm for generating random representative volume elements (RVEs) with statistical equivalent fiber distribution against the actual material microstructure. The realistic statistical da...

in this paper, by using of frobenius theorem a relation between lie subalgebras of the lie algebra of a top space t and lie subgroups of t(as a lie group) is determined. as a result we can consider these spaces by their lie algebras. we show that a top space with the finite number of identity elements is a c^{∞} principal fiber bundle, by this method we can characterize top spaces.

Understanding the structural organization of eukaryotic chromatin and its control of gene expression represents one of the most fundamental and open challenges in modern biology. Recent experimental advances have revealed important characteristics of chromatin in response to changes in external conditions and histone composition, such as the conformational complexity of linker DNA and histone t...

This paper discusses the importance of stress-induced contributions to the photo-induced birefringence observed in fiber Bragg gratings. Optical tomography measurements are performed in exposed and unexposed fibers to extract the stress profiles induced by UV-writing of fiber Bragg gratings for various exposure levels. A photoelastic analysis and a high-order isoparametric finite elements metho...

Integration of micro-optical elements (MOEs) with optical fiber at top-end was realized by use of focused ion beam (FIB) direct milling. The designed MOEs (micro-refractive lens, microdiffractive lens with continuous relief, and micro-gratings) were directly milled by the FIB with ion energy and ion beam current of 40 keV and 569 pA, respectively, in the core area of both single mode fiber and ...

High bandwidth requirements make the use of fiber optics very attractive for Metropolitan Area Network (MAN) implementations. Several fiber optics MAN architectures have been proposed. A common drawback of such architectures is the presence of active processing components (e.g. ring interfaces, switches, gateways) at intermediate points along the path. Such elements tend to reduce reliability a...

We demonstrate a Single-Mode (SM) Large-Mode-Area (LMA) ytterbium-doped PCF rod fiber laser with stable and close to diffraction limited beam quality with 110W output power. Distributed-Mode-Filtering (DMF) elements integrated in the cladding of the rod fiber provide a robust spatial mode with a Mode-Field-Diameter (MFD) of 59μm. We further demonstrate high pulse energy Second-Harmonic-Generati...

We demonstrate an all-fiber Tm(3+)-doped silica fiber laser operating at a wide selectable wavelength range by using different fiber Bragg gratings (FBGs) as wavelength selection elements. With a specifically designed high reflective (HR) FBG and the fiber end as an output coupler, the lasing in the range from 1975 nm to 2150 nm with slope efficiency of >30% can be achieved. By employing a low ...

Single-mode optical D-fiber is fabricated and coupled to single-mode acrylic waveguides by use of a novel technique utilizing alignment ways and a transcision. The D-fiber is fabricated by lapping the cladding layer of a single-mode fiber to the core. Optical waveguides and alignment ways are made with polymers by photolithography. This technique allows coupling of the optical elements by means...