We demonstrate a novel amplification regime in counter-pumped, relatively long (2 meters), large mode area, highly Yb-doped and polarization-maintaining tapered fiber, which offers high peak power directly from the amplifier. The main feature of this is that amplifying signal propagates through thin part fiber without experiences an extremely gain thick where most pump absorbed. In regime, we have demonstrated 8 ps pulse to up 0.76 MW, limited by appearance stimulated Raman scattering. same...

Luminescence emission and excitation spectra of bismuth-doped silica optical fibers free other dopants have been obtained to construct an emission-excitation map in a wide wavelength range 400-1600 nm. The main low-lying energy levels the bismuth active centers such determined. For first time (to our knowledge), gain lasing fibers. A 8 dB has achieved with pump power 340 mW, cw fiber laser emitting at 1460 nm output 40 mW efficiency ≈3% created.

We have studied UV excitation spectra of IR luminescence in bismuth-doped glasses various compositions and obtained energy level diagrams IR-emitting bismuth-related active centres (BACs) associated with silicon germanium atoms up to ~5.2 eV over the ground level. A possible diagram BACs phosphosilicate glass has been proposed. The peaks for shown considerably overlap absorption bands Bi3+ ion, suggesting that may participate BAC formation.

We present a composite optical fiber with Er/Yb co-doped phosphate-glass core in silica glass cladding as well pumped laser. The fabrication process, properties, and lasing parameters are described. slope efficiency under 980 nm pumping reached 39% respect to the absorbed pump power 28% coupled power. Due high doping level of phosphate optimal length was several times shorter than that fibers.

Optical fibre preforms and fibres with a bismuth-doped silica core containing no other dopants have been fabricated by the powder-in-tube technique. The optical loss has measured for first time in such wide spectral range, from 190 to 1700 nm. We studied luminescence of active bismuth centres lifetime some their bands both drawn out them.

A helium-xenon gas-discharge fiber laser based on hollow-core is demonstrated for the first time. Being pumped by a pulsed microwave radiation at 2.45 GHz in slot antenna configuration, operates 2.03 μm quasi-continuous-wave mode with output power of ∼2 mW. The performance depends strongly pressure gas mixture and mole fraction Xe atoms. results obtained opens up new opportunities developing type lasers that can potentially generate wide spectral range from ultraviolet to mid-infrared...

The visible and near-IR absorption luminescence bands of bismuth-doped silica germanosilicate fibres have been measured for the first time as a function temperature. temperature-dependent IR lifetime bismuth-related active centre associated with silicon in fibre has determined. Bi3+ profile across preform is shown to differ markedly from distribution IR-emitting bismuth centres silicon. present results strongly suggest that comprises lowvalence ion an oxygen-deficient glass network defect.

For the first time, to best of our knowledge, we present an all-fiber polarization-maintaining passively mode-locked picosecond laser operated at 980 nm. The cavity had a ring configuration with semiconductor saturable absorber mirror as mode-locking element. As active medium, used specially designed cladding-pumped Yb-doped fiber reduced cladding-to-core diameter ratio. was self-starting and in net normal dispersion regime, where spectral profile gain medium acted filter By intracavity...

We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation stable Yb{sup 2+} ions network under IR laser pumping at a wavelength λ = 915 nm UV irradiation excimer (λ 193 nm). performed comparative studies crystals excitation nm. The mechanism behind aluminium – oxygen hole centres (Al-OHCs), common to YAG glass, has been identified: photoinduced 3+} charge-transfer state...

We report the first silica-based hollow-core microstructured fibre for UV spectral range, with a reflective cladding formed by single ring of capillaries. The optical loss in at wavelength is . demonstrate distinctions between propagation high-order modes and fundamental mode hollow core 'revolver' noncontacting capillaries examine effect multimode excitation on transmission bandwidth fibre. Based experimental data numerical simulation results, we formulate recommendations how to reduce...

An operation of a linearly polarized Raman fiber laser with random distributed feedback based on polarization-maintaining twin-core (TCF) is demonstrated for the first time, to best our knowledge. The results indicate that TCF allows one obtain generation linewidth about five times smaller than conventional similar parameters. reasons narrowing include both weakening nonlinear effects due power density reduction and spectrally selective properties TCF.

A 2.03 μm gas-discharge fiber laser based on atomic xenon is investigated. Various gas mixtures, such as He–Xe, Ar–Xe, He–Ar–Xe, and He–Ne, are studied by optical emission spectroscopy. The possibility of extending generation further into the mid-infrared range analyzed.

Luminescence excitation spectra of active centers in bismuth-doped vitreous SiO(2) and GeO(2) optical fibers under the two-step have been obtained for first time. The results revealed only one bismuth-related IR center formed each these fibers. observed luminescence bands at 1430 nm (1650 nm) 830 (950 nm), yellow-orange (red) band 580 (655 violet (blue) 420 (480 belong to this (vitreous GeO(2)), correspondingly.

This letter is devoted to fabrication and tests of an optical fiber with a phosphate glass core in silica cladding. The preform was made by melting Yb, Er co-doped laser high-purity tube. 1.54 μm action demonstrated under 1.06 pumping into the Yb absorption band.

Abstract We have developed and demonstrated a polarisation-maintaining single-mode ytterbium-doped fibre for light amplification at wavelength near 0.976 μm in an all-fibre configuration. A distinctive feature of the proposed design is low losses due to fusion splices with standard having core diameter 10 μm, which has made it possible produce small-signal amplifier gain threshold 3 W differential pump-to-signal conversion efficiency 9.8 % saturation regime. The been shown be well-suited...

Abstract We proposed and experimentally demonstrated a technique for the suppression of unwanted modes in double-clad fibers with high core-to-clad diameter ratio by introducing high-index absorbing inclusions into first cladding fibers. These disturb shape undesirable modes, noticeable part power becomes localized inside inclusion, resulting an increase propagation loss these modes. Two fiber designs were studied realized: one cylindrical symmetry ring as inclusion another rods inserted...

Abstract We consider a fibre laser system generating ∼10-μJ, ∼500-fs pulses with peak power of ∼10 MW at repetition rate 100 kHz and emission wavelength 1.56 μm. The is based on master oscillator – amplifier configuration. ensures chirped-pulse amplification. are then compressed by dispersive grating compressor. output stage specially designed tapered large mode area erbium-doped for suppressing nonlinear effects. experimental data agree numerical simulation results the stretcher, stretcher...

A cladding-pumped all-fiber chirped femtosecond pulse Yb-doped mode-locked laser operating near 977 nm was demonstrated for the first time. Nonlinear polarization evolution used as mode-locking mechanism. The self-starting and extremely stable (the stability of repetition rate 41.6 MHz better than that 15 Hz). Amplification achieved using a specially designed fiber. main feature current design its increased intracavity nonlinearity, which resulted in strong self-phase modulation significant...

To excite plasma in the core of a hollow fiber, scheme similar to slot antenna wall metal microwave waveguide was proposed and implemented. An analytical estimate magnitude electric field region where fiber with is placed has been obtained. Using scheme, possibility maintaining argon diameter as small 110 μm demonstrated. The total length column hollow-core up 25 cm at Ar pressure ~10 Torr. frequency radiation used 2.4 GHz, average generated power below 20 W. obtained luminescence spectra...

The paper presents the results of theoretical and experimental studies all-glass leakage channel microstructured optical fibers (MOFs) with a large mode area low bending losses. These MOFs contain two layers fluorine-doped silica glass elements reduced refractive index, different diameters, distances between them. A numerical analysis properties these was performed using finite element method. losses for fundamental higher-order modes were calculated in spectral range from 0.65 μm to 1.65...

We demonstrated an optimization of a picosecond fiber amplifier based on Yb-doped tapered in spectral range 1030 nm. Nonlinear effects limiting peak power scaling (stimulated Raman scattering and four-wave mixing) were studied factors affecting their threshold established, such as gain, diameter profile along the length taper, output mode field diameter, numerical aperture pump. By determining optimal amplification regime manufacturing advanced fibers, we amplified 13 ps pulses to...

A novel Yb-doped fiber design for improved lasing near 976 nm based on spectral filtering of the amplified spontaneous emission 1030 was realized and investigated. very sharp short-pass filter implemented by adding appropriately chosen high-index absorbing rods into silica cladding. In this case, resonant interaction core mode with rod could be controlled bending, which allows precise adjustment stop-band position. It shown that utilization Sm-doped one to achieve high absorption at unwanted...