Explanipedia

Judd-Ofelt analysis of thulium-doped alumino-silicate optical glass prepared by MCVD combined with nanoparticle doping Open

Petr Vařák, Michal Kamrádek, Pavla Nekvindová, Ján Hrabovský, Pavel Peterka · 2025

Long period grating in ZBLAN fiber using the pull-and-heat method Open

Antreas Theodosiou, Yauhen Baravets, Pavel Peterka · 2025

This Letter demonstrates a method for long-period grating inscription in fluoride fibers using the pull-and-heat method. It also presents an analysis of fiber deformation when subjected to a combination of heating temperature, duration, an…

Holmium-doped silica fibers combining high doping and high efficiency Open

Jan Pokorný, Bára Švejkarová, Jan Aubrecht, Michal Kamrádek, Ivo Bartoň , et al. · 2025

We present a 2.1 µm holmium-doped fiber laser, core pumped by a 1.94 µm thulium-doped fiber laser. The laser is based on an in-house drawn, highly holmium-doped silica fiber (3850 mol ppm). We achieved a high output power up to 22.5 W and …

Understanding the Temperature Conditions for Controlled Splicing Between Silica and Fluoride Fibers Open

Antreas Theodosiou, Ori Henderson‐Sapir, Yauhen Baravets, Oliver T. Cobcroft, Samuel M. Sentschuk , et al. · 2025

This study explores the efficacy of thermal splicing conditions between silica and zirconium‐fluoride fibers, focusing on achieving mechanical strength between the two fibers. A comprehensive characterization of the thermal profile in the …

Thulium fiber lasers with longitudinally modified concentration Open

Bára Švejkarová, Martin Grábner, Jan Aubrecht, Richard Švejkar, Jan Pokorný , et al. · 2025

High-power fiber lasers generate local heat load extremes during their operation, which increase the fiber temperature and lead to adverse thermal effects, such as transverse mode instability or cladding/coating thermal damage. The local t…

Doped and structured silica optical fibres for fibre laser sources Open

Ivan Kašı́k, Ivo Bartoň, Michal Kamrádek, Ondřej Podrazký, Jan Aubrecht , et al. · 2024

Nanoparticle doping as a way to enhance holmium fiber lasers efficiency Open

Michal Kamrádek, Ivan Kašı́k, Jan Aubrecht, Petr Vařák, Ondřej Podrazký , et al. · 2024

Nanoparticle doping and molten-core methods towards highly thulium-doped silica fibers for 0.79 μm-pumped 2 μm fiber lasers – A fluorescence lifetime study Open

Petr Vařák, Martin Leich, Michal Kamrádek, Jan Aubrecht, Ondřej Podrazký , et al. · 2024

We study the fluorescence lifetime of Thulium-doped silica fibers for efficient laser operation in the 2 μm "eye-safe" wavelength range pumped by 0.79 μm radiation. A large set of optical fibers prepared by Modified Chemical Vapor Depositi…

Rise of amplified spontaneous emission in high-power thulium-doped fiber lasers and amplifiers due to self-heating Open

Martin Grábner, Bára Švejkarová, Jan Aubrecht, Jan Pokorný, Pavel Honzátko , et al. · 2024

The performance of high-power fiber lasers is limited by different thermal mechanisms such as a variationof spectroscopic quantities with temperature. In this paper, the effect of temperature dependent thuliumcross sections on high-power t…

Understanding the temperature conditions for controlled splicing between silica and fluoride fibers Open

Antreas Theodosiou, Ori Henderson‐Sapir, Yauhen Baravets, Oliver T. Cobcroft, Samuel M. Sentschuk , et al. · 2024

This study explores the efficacy of thermal splicing conditions between silica and zirconium-fluoride fibers, focusing on achieving mechanical strength between the two fibers. A comprehensive characterization of the thermal profile in the …

Depressed-cladding thulium-doped fiber for applications below 1800 nm Open

Jan Pokorný, Jan Aubrecht, Michal Kamrádek, Bára Švejkarová, Petr Vařák , et al. · 2024

We present a thulium-doped silica fiber, featuring a depressed cladding, for applications at wavelengths below 1800 nm. The depressed cladding is used as a distributed filter suppressing amplified spontaneous emission at longer wavelengths…

Broadband thulium fiber amplifier for spectral region located beyond the L-band Open

Jan Aubrecht, Jan Pokorný, Bára Švejkarová, Michal Kamrádek, Pavel Peterka · 2024

We present the development of a pair of silica-based thulium-doped fiber amplifiers working together in a broad spectral range from 1.65 µm to 2.02 µm. For the one optimized for shorter wavelengths, we designed and prepared optical fiber w…

Heat treatment and fiber drawing effect on the matrix structure and fluorescence lifetime of Er- and Tm-doped silica optical fibers Open

Petr Vařák, Michal Kamrádek, Jan Aubrecht, Ondřej Podrazký, Jan Mrázek , et al. · 2024

We investigate the influence of the optical fiber fabrication process on the fluorescence lifetime of Er 3+ and Tm 3+ ions. Optical fiber preforms were prepared using the MCVD method combined with Al 2 O 3 nanoparticle doping. The preforms…

Pedestal-cladding-pumped holmium fiber laser optimization using an analytical model Open

Jan Pokorný, Jan Aubrecht, Martin Grábner, Pavel Peterka · 2024

An analytical model of holmium-doped fiber laser is used to calculate optimal fiber length, pump wavelength and signal wavelength under in-band pumping conditions while considering fiber losses. The calculations show the advantages of a ne…

Challenges of temperature-dependent emission spectra measurement of thulium-doped fibers around 2 µm Open

Bára Švejkarová, Jan Aubrecht, Richard Švejkar, Martin Grábner, W.A. Clarkson , et al. · 2024

Understanding temperature’s impact on spectroscopic properties in high-power thulium-doped fiber lasers is crucial for accurate numerical modeling. Our study discusses influence of thulium concentration and temperature-induced bend losses …

Development of pedestal-free large mode area fibers withTm3+ doped silica nanostructured core Open

Pavel Peterka, Jan Aubrecht, Dariusz Pysz, Marcin Franczyk, O. Schreiber , et al. · 2023

We present the pedestal-free thulium doped silica fiber with a large nanostructured core optimized for fiber lasers. The fiber is composed of over 6 thousand thulium doped silica nanorods with a diameter of 71 nm each which form a nanostru…

Post-radiation effects of core pumped monolithic holmium-doped silica fibre lasers Open

Antreas Theodosiou, Λουκάς Κουτσοκέρας, Andreas Ioannou, Andrei Stăncălie, Daniel Neguţ , et al. · 2023

We present our recent studies regarding the influence of ionized radiation when a monolithic Holmium fibre laser was exposed under a total dose of 350 Gy of γ-radiation. Since fibre lasers have many uses for space applications, it is impor…

High harmonic generation enhanced by magnetic dipole resonance in an amorphous silicon metasurface Open

Pavel Peterka, Z. Šobáň, F. Trojánek, P. Malý, Martin Kozák · 2023

We report on the enhancement of high harmonic generation (HHG) yield in a metasurface consisting of amorphous silicon disks in a periodic array on an insulator substrate. The structure was designed and optimized using the finite-difference…

csnTm_par_lowT.txt Open

Bára Jiříčková, Martin Grábner, César Jáuregui, Jan Aubrecht, O. Schreiber , et al. · 2023

Fitted parameters of temperature dependent normalized thulium cross-section spectra

Gain-controlled broadband tuneability in self-mode-locked Thulium-doped fibre laser Open

Dennis C. Kirsch, Anastasia Bednyakova, Petr Vařák, Pavel Honzátko, Benoît Cadier , et al. · 2022

Ensuring self-driven mode-locking and broadband wavelength tuneability in all-fibre-integrated femtosecond laser sources enables a new level of their versatility and extends areas of their applications. Principle limitations for this are t…

Luminescence and laser properties of RE-doped silica optical fibers: The role of composition, fabrication processing, and inter-ionic energy transfers Open

Petr Vařák, Michal Kamrádek, Jan Mrázek, Ondřej Podrazký, Jan Aubrecht , et al. · 2022

Silica glass doped with rare-earth ions remains one of the most frequently used materials for fiber lasers and amplifiers, owing to various advantages such as high thermal resistance, mechanical and chemical durability, high transparency u…

Formula for temperature distribution in multi-layer optical fibres for high-power fibre lasers Open

Martin Grábner, Pavel Peterka, Pavel Honzátko · 2022

High power fibre lasers need to be cooled efficiently to avoid their thermal damage. Temperature distribution in fibre should be estimated during the fibre laser design process. The steady-state heat equation in a cylindrical geometry is s…

Near perfect two-photon interference out a down-converter on a silicon photonic chip Open

Pavel Peterka, Florent Mazeas, Edgars Nitišs, Ozan Yakar, Anton Stroganov , et al. · 2022

Integrated entangled photon-pair sources are key elements for enabling large-scale quantum photonic solutions, and addresses the challenges of both scaling-up and stability. Here we report the first demonstration of an energy-time entangle…

High-power laser testing of calcium-phosphate-based bioresorbable optical fibers Open

Pavel Peterka, Diego Pugliese, Bára Jiříčková, Nadia G. Boetti, Hana Turčičová , et al. · 2021

Silica optical fibers are employed in endoscopy and related minimally invasive medical methods thanks to their good transparency and flexibility. Although silicon oxide is a biocompatible material, its use involves a serious health risk du…

Energy transfer coefficients in thulium-doped silica fibers Open

Michal Kamrádek, Jan Aubrecht, Petr Vařák, Jakub Cajzl, Václav Kubeček , et al. · 2021

Energy transfer coefficients in thulium-doped silica fibers are key parameters for a reliable numerical modeling and optimization of high-power fiber lasers pumped at 790 nm and emitting around eye-safer wavelength of 2 µm. We report on de…

Holmium monolithic fiber lasers: an investigation of the fiber Bragg grating spatial dimensions on fiber laser performance Open

Antreas Theodosiou, Jan Aubrecht, Pavel Peterka, Kyriacos Kalli · 2021

We have investigated how the physical dimensions of a fiber Bragg grating (FBG) may affect the performance of a monolithic fiber laser system. In particular, we perform a series of direct laser inscriptions in a Holmium-doped single mode f…

Simulations of Pump Absorption in Tandem-Pumped Octagon Double-Clad Fibers Open

Martin Grábner, K. Nithyanandan, Pavel Peterka, Pavel Koška, A.A. Jasim , et al. · 2021

The cladding pumping within a double-clad fiber structure is an effective technique to convert high-power multimode beam into high-power, almost diffraction limited beam. Since the pump efficiency is limited by the presence of higher skew-…

Active Optical Fibers and Components for Fiber Lasers Emitting in the 2-μm Spectral Range Open

Filip Todorov, Jan Aubrecht, Pavel Peterka, O. Schreiber, A.A. Jasim , et al. · 2020

Laser sources emitting in the infrared range at around 2 µm are attracting great interest for a variety of applications like processing of transparent thermoplastic polymers in industry as well as plenty of applications in medicine, spectr…

Novel geometries and layouts of double-clad fibers for fiber lasers Open

Pavel Peterka, Pavel Koška, A.A. Jasim, Martin Grábner, Jan Aubrecht , et al. · 2020

Impact of shaping optical fiber preforms based on grinding and a CO2 laser on the inner-cladding losses of shaped double-clad fibers Open

A.A. Jasim, Ondřej Podrazký, Pavel Peterka, Michal Kamrádek, Ivan Kašı́k , et al. · 2020

We experimentally compared for the first time, two techniques of optical fiber preform shaping based on the mechanical grinding and thermal CO 2 laser processing from the point of the inner-cladding losses. The shaped preforms were fabrica…

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