Search results for "Bragg Grating"

Radiation tolerant fiber Bragg gratings for high temperature monitoring at MGy dose levels

2014

International audience; We report a method for fabricating fiber Bragg gratings (FBG) resistant to very severe environments mixing high radiation doses (up to 3 MGy) and high temperatures (up to 230 degrees C). Such FBGs have been written in two types of radiation resistant optical fibers (pure-silica and fluorine-doped cores) by exposures to a 800 nm femtosecond IR laser at power exceeding 500 mW and then subjected to a thermal annealing treatment of 15 min at 750 degrees C. Under radiation, our study reveals that the radiation induced Bragg wavelength shift (BWS) at a 3 MGy dose is strongly reduced compared to responses of FBGs written with nonoptimized conditions. The BWS remains lower t…

Direct Bragg grating writing in a hybrid PDMS/silica photonic crystal fiber

2011

Infiltration of materials into the air holes of the PCFs can potentially manipulate their optical properties creating a new category of fibers termed as hybrid PCFs [1] and many devices based on hybrid PCFs have been developed [2–5]. Recently, a hybrid PCF with poly-dimethylsiloxane (PDMS) elastomer inclusions has been demonstrated [6]. PDMS is widely used in the area of photonics and optofluidics. It is highly transparent with a refractive index ∼1.41, conserving the total internal reflection guiding mechanism of the hybrid PCF. When PDMS is irradiated with UV light its refractive index increases [7]. In this paper we present the first example of a Bragg grating directly written using UV l…

Design and Fabrication of Terahertz Bragg Gratings on a Two-Wire Waveguide

In this study, we present the design and the fabrication procedure of waveguide-integrated Bragg Gratings operating at THz frequencies.

Spectral properties of a variable period Bragg grating including a segment isolated of external deformations

2017

In this work the behavior of a Bragg grating of variable period (usually called a linearly chirped fiber Bragg grating — CFBG) is analyzed when a small portion of it is fixed so that its properties remain unchanged, while the rest of the grating is affected by a longitudinal deformation. The system was simulated using the Transfer Matrix Method to obtain its behavior under different levels of deformation and it was observed the appearance of negative peaks in the spectral response (transmission peaks). The analysis allowed characterizing the system with different sizes of the fixed portion (defects) (0.5 to 6 mm), for a grating with 10 cm long and 3 nm spectral width.

Highly Efficient Holmium-Doped All-Fiber ∼2.07-μm Laser Pumped by Ytterbium-Doped Fiber Laser at ∼1.13 μm

2018

We report a 2.07-μm Holmium-doped all-fiber laser (HDFL) pumped by a 1.13-μm Ytterbium-doped fiber laser (YDFL). Home-made alumino–germano–silicate holmium-doped fiber (HDF) served here as an active medium, optimized in terms of chemical composition and co-dopants’ concentrations. Laser action at 2.07 μm was assessed in simple Fabry–Perot cavity, formed by a couple of home-made fiber Bragg gratings (FBGs), inscribed directly in the HDF; this allowed notable diminishing of intracavity loss of the 2.07-μm laser. HDF was in-core pumped by the 1.13-μm double-clad YDFL with a power of ∼12.5 W, in turn pumped in-clad by a laser diode (LD) operated at 0.97 μm with ∼24.5-W output. Using optimal len…

Passively mode-locked laser based on an ultra-large dispersion Yb-doped fiber

2013

Summary form only given. We report on the first realization of a passively mode-locked oscillator featuring an ultra-large dispersion Yb-doped Bragg fiber. The gain medium is a double-clad Bragg fiber featuring a 20 μm Yb-doped core surrounded by a 120 μm inner cladding [1]. The 2 m long gain fiber is cladding-pumped with a fiber-coupled laser diode emitting at 976 nm. Passive mode locking is achieved by the combined actions of nonlinear polarization evolution and a SESAM. Mode-locking is initiated by optimizing the saturation criteria on the saturable absorber mirror using an adequate focusing lens. The emission wavelength of the oscillator is controlled using a passive spectral filter int…

Parabolic pulse generation through passive reshaping of gaussian pulses in a normally dispersive fiber

2007

We numerically and experimentally demonstrate that a Gaussian pulse can be reshaped into a pulse with a stable parabolic intensity profile during propagation in normally dispersive nonlinear fibers.

New fiber laser architecture with transform-limited nonlinear spectral compression

2012

International audience; We numerically demonstrate a new fiber laser architecture supporting spectral compression of negatively chirped pulses in passive normally dispersive fiber. Such a process is beneficial for improving the energy efficiency of the cavity as it prevents narrow spectral filtering from being highly dissipative. The proposed laser design provides an elegant way of generating transform-limited picosecond pulses.

All-optical fiber-based devices for ultrafast amplitude jitter magnification

2012

International audience; We propose two fiber-based architectures that enable the all-optical magnification of ultrafast amplitude fluctuations of picosecond or femtosecond pulse trains. An increase of the fluctuations by more than one order of magnitude is experimentally achieved.

Parabolic pulse formation and applications

2009

Parabolic pulses in optical fibers have stimulated an increasing number of applications. We review here the physics underlying the generation of such pulses as well as the results obtained in a wide-range of experimental configurations.