Search results for "fiber laser"
showing 10 items of 200 documents
Toward a wave turbulence formulation of statistical nonlinear optics
2012
International audience; During this last decade, several remarkable phenomena inherent to the nonlinear propagation of incoherent optical waves have been reported in the literature. This article is aimed at providing a generalized wave turbulence kinetic formulation of random nonlinear waves governed by the nonlinear Schrodinger equation in the presence of a nonlocal or a noninstantaneous nonlinear response function. Depending on the amount of nonlocal (noninstantaneous) nonlinear interaction and the amount of inhomogeneous (nonstationary) statistics of the incoherent wave, different types of kinetic equations are obtained. In the spatial domain, when the incoherent wave exhibits fluctuatio…
Broadband tuning of a long-cavity all-fiber mode locked Thulium-doped fiber laser using an acousto-optic bandpass filter
2019
A long-cavity passively mode-locked thulium-doped all-fiber laser is reported incorporating a tapered acousto-optic tunable bandpass filter (AOTBF). The operation of the AOTBF relies on the intermodal coupling between core and cladding modes when a flexural acoustic wave propagates along an 80-microm tapered fiber. The filter works in transmission and exhibits a 3-dB bandwidth of 9.02 nm with an insertion loss of 3.4 dB. The laser supports ultrashort pulse generation at a low repetition rate of 784.93 kHz. Optical pulses with 2.43 nm of optical bandwidth and 2.1 ps pulse duration were obtained in a broad tuning range from 1824.77 to 1905.16 nm.
Polarized multiplex coherent anti-Stokes Raman scattering using a picosecond laser and a fiber supercontinuum
2011
International audience; We perform multiplex coherent anti-Stokes Raman scattering (CARS) micro-spectroscopy with a picosecond pulsed laser and a broadband supercontinuum (SC) generated in photonic crystal fiber. CARS signal stability is achieved using an active fiber coupler that avoids thermal and mechanical drifts. We obtain multiplex CARS spectra for test liquids in the 600–2000 cm−1 spectral range. In addition we investigate the polarization dependence of the CARS spectra when rotating the pump beam linear polarization state relative to the linearly polarized broad stokes SC. From these polarization measurements we deduce the Raman depolarization ratio, the resonant versus nonresonant …
Er3+-doped GeGaSbS glasses for mid-IR fibre laser application: Synthesis and rare earth spectroscopy
2008
International audience; With an infrared transparency extended to 10 µm, low multiphonon relaxation rates and suitable rare earth solubility, sulphide glasses in the Ge-Ga-Sb-S system allow radiative emission from rare earth ions in the mid-IR range. The Er3+ ion, widely studied in glass fibres for optical amplification at 1.5 µm, presents an interesting transition for mid-IR applications around 4.5 µm (4I9/2→ 4I11/2). Thus, the aim of this work is to evaluate the Er3+-doped Ge20Ga5Sb10S65 glass as a potential fibre laser source operating in the 3-5 µm mid-IR spectral region. For that purpose, absorption and emission spectra were recorded from visible to mid-IR and the radiative lifetimes o…
Q-switching of an erbium-doped fibre laser modulated by a Bragg grating fixed to a piezoelectric
2003
The performance of the Q-switched erbium-doped fibre laser with two fibre Bragg gratings as cavity mirrors was theoretically analysed, employing a set of rate equations for the ion populations and the photon flux inside the cavity. The simulation considers a system where the pulsed laser emission is produced by the temporal modulation of a Bragg grating fixed to a piezoelectric and operating in the 1550 nm spectral region. The temporal evolution of different frequency components of the laser emission produced is governed by the instantaneous overlap between the two gratings. Theoretical results are in agreement with previously reported experimental values.
Tunable dual-wavelength operation of an all- fiber thulium-doped fiber laser based on tunable fiber Bragg gratings
2018
Tunable dual-wavelength emission of a Tm-doped fiber laser based on two fiber Bragg gratings (FBGs) is experimentally demonstrated. By using two FBGs with central wavelengths at 2069.30 and 2069.44 nm, stable dual-wavelength laser generation in the 2 ?m wavelength region is achieved by adjusting the differential loss of the two wavelengths in the laser cavity. Strain applied on the FBG allows independent tuning of the simultaneously generated wavelengths with separation between the laser lines in a range from 0.54 to 9 nm. The laser has output power fluctuations less than 0.093% for an output power of 77.3 mW.
Transition from polarization disorder to antiphase polarization domains in a fiber laser
2014
Adjusting polarization coupling in a fiber ring laser may lead to anti-synchronization of spatio-temporal disorder into ordered laminar states of orthogonal polarization temporal domains, as well as stable lattices of soliton trains.
Effect of microstructure and chemical composition on localized corrosion resistance of a AISI 304L stainless steel after nanopulsed-laser surface mel…
2015
Abstract Changes induced in the surface properties of AISI 304L stainless steel when it is treated with a nanopulsed ytterbium-doped fiber laser were investigated to determine the microscale distribution of its physico-chemical properties. A Gaussian energy distribution was created with a radius of 71 μm (1/e2) at the focal point. Local investigations were carried out using transmission electron microscopy to consider the effect of overlapping individual laser impacts. The results obtained reveal that laser surface melting leads to changes in the crystallographic structure of the steel through the formation of a δ-ferritic phase. It also results in the creation of an oxide layer that increa…
Optical fiber diffusive tip designs for medical laser-lightguide delivery systems
1994
Medical laser radiation delivery instruments with diffusive tips on the distal ends of plastic-clad silica optical fibers have been designed, tested, and manufactured. The instruments are optimized for endoscopic, therapeutic, dermatologic and surgical laser treatment. The diffusive tips provide radial, cylindrical and aside-conical spatial distributions of the output radiation. Optical schemes concerning each type of the tip and the corresponding spatial distribution functions of the output radiation are presented and analyzed. Designs of the lightguide instruments for surgical and dermatological procedures demanding local high-power laser irradiation are also discussed.
Actively mode-locked all-fiber laser by 5 MHz transmittance modulation of an acousto-optic tunable bandpass filter
2018
Active mode-locking of an all-fiber ring laser by transmittance modulation of an in-fiber acousto-optic tunable bandpass filter (AOTBF) is reported. Cavity loss modulation is achieved by full acousto-optic mode re-coupling cycle induced by standing flexural acoustic waves. The modulator permits the implementation of 28 dB of nonresonant light suppression, 1.4 nm of modulation bandwidth, 74% of modulation depth and 4.11 dB of optical loss in a 72.5 cm-long all-fiber configuration. The effects of the modulated AOTBF on the laser performance are investigated. Transform-limited optical pulses of 8.8 ps temporal width and 6.0 W peak power were obtained at 4.87 MHz repetition rate.