Dr. Richard Švejkar Profile

Dr. Richard Švejkar

Physicist

SPIE Involvement:

Author

Publications (15)

Proceedings Article | 12 March 2024 Poster + Paper

Determining the relative impact of quantum efficiency and core propagation loss on efficient power scaling of thulium-doped silica fibre lasers

Martin Paul Buckthorpe, Richard Švejkar, William Andrew Clarkson

Proceedings Volume 12864, 128640W (2024) https://doi.org/10.1117/12.3002641

KEYWORDS: Quantum efficiency, Thulium, Quantum measurement, Fiber lasers, Thermal effects, Silica, Doping, Quantum experiments, Fiber Bragg gratings, Structured optical fibers

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Proceedings Article | 9 June 2023 Poster + Paper

Acousto-optically Q-switched Er:YAP laser emitting at 2.8μm

Richard Švejkar, Dominika Popelová, Jan Šulc, Helena Jelínková

Proceedings Volume 12577, 125770F (2023) https://doi.org/10.1117/12.2665614

KEYWORDS: Laser resonators, Pulsed laser operation, Q switches, Crystals, Q switched lasers, Laser radiation, Laser crystals, Erbium

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Proceedings Article | 8 March 2023 Poster + Paper

Temperature dependence of spectroscopy and laser parameters of Er:Y2O3 ceramic from 80 to 300 K

Richard Švejkar, Jan Šulc, Helena Jelínková

Proceedings Volume 12399, 123990N (2023) https://doi.org/10.1117/12.2647227

KEYWORDS: Ceramics, Fluorescence, Erbium, Pulsed laser operation, Laser resonators, Laser radiation, Spectroscopy, Crystals

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In this work, the spectroscopy and laser characteristics of the ceramic Er:Y₂O₃ are presented in the temperature range from 80 to 300 K. Er:Y₂O₃ ceramic (5 at. % of Er³⁺, Baikowski Co., Ltd.) had the form of a rectangular block (thickness 9 mm) with plan-parallel polished faces (cross-section 3 × 3 mm) without anti-reflection coatings. The active medium was attached to the copper cold finger of the liquid nitrogen cryostat in a vacuum chamber. The pumping of Er:Y₂O₃ was carried out by radiation from fibre-coupled laser diode (pulse duration 3 ms, repetition rate 16.6 Hz, wavelength 972 nm). All spectroscopy measurements – transmission, fluorescence and up-conversion spectra together with fluorescence decay times at ⁴I_11/2 and ⁴I_13/2 were obtained in the temperature range from 80 to 300 K. The fluorescence decay time of manifold 4 I11/2 (upper laser level) is slightly increasing with rising temperature from 325 μs (80 K) to 342 μs (170 K) and then its decreasing to 295 μs (300 K). On the other hand, the decay time of lower laser lever ⁴I_13/2 is increasing together with a rising temperature from 3.6 ms (80 K) to 4.6 ms (300 K). Moreover, it was obvious that with decreasing temperature, the intensity of green up-conversion radiation (564 nm) increased. For laser experiments a hemispherical resonator (80 mm in length) with a flat pumping mirror (HT < 94 % @ 960 - 980 nm and HR < 99 % @ 2.65 - 3 μm) and spherical output coupler (r = 100 mm, R = 95 % @ 2.65 - 2.95 μm) were used. Er:Y₂O₃ laser was operated in the pulsed regime to prevent damage to the active medium, the highest slope efficiency 9.5 % (with respect to absorbed power) and maximum output power of 83 mW were reached at a duty cycle of 5 %. With rising temperature the slope efficiency was decreasing down to 5 % at 300 K, on the other hand the laser threshold with respect to absorbed mean power was increased from 50 mW (80 K) to 150 mW (300 K). The emitted laser wavelength by the Er:Y₂O₃ laser was slightly changed due to the heating of the active medium from 2744 nm (at 80 K) to 2742 nm (at 300 K). The erbium-doped ceramic active media can be used as an alternative to crystals because of its easier fabrication compared to single-crystal sesquioxides, which require high melting point and special materials for crucible during growing process.

Proceedings Article | 4 March 2022 Poster + Presentation + Paper

Er,Pr:GGAG spectroscopy and laser characteristics at 3 μm in temperature range from 80 K to 300 K

Richard Švejkar, Jan Šulc, Pavel Boháček, Michal Němec, Helena Jelínková, Bohumil Trunda, Lubomír Havlák, Martin Nikl, Karel Jurek

Proceedings Volume 11980, 119800A (2022) https://doi.org/10.1117/12.2604228

KEYWORDS: Crystals, Absorption, Pulsed laser operation, Laser spectroscopy, Spectroscopy, Laser resonators, Erbium

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Proceedings Article | 21 February 2020 Paper

Temperature influence on Er:GGAG crystal spectroscopic properties and lasing at 3 μm

Richard Švejkar, Jan Šulc, Pavel Boháček, Michal Němec, Jan Kratochvíl, Helena Jelínková, Bohumil Trunda, Lubomír Havlák, Martin Nikl, Karel Jurek

Proceedings Volume 11259, 112591Q (2020) https://doi.org/10.1117/12.2541965

KEYWORDS: Crystals, Luminescence, Erbium, Pulsed laser operation, Absorption, Spectroscopy, Laser dentistry, Laser resonators, Output couplers

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Proceedings Article | 26 April 2019 Presentation + Paper

Passively Q-switched Er,La:SrF2-CaF2 laser at 2.74 μm

Richard Švejkar, Jan Šulc, Helena Jelínková, Maxim Doroshenko, Vasily Konyushkin, Andrei Nakladov, Vjatcheslav Osiko

Proceedings Volume 11033, 110330F (2019) https://doi.org/10.1117/12.2520268

KEYWORDS: Pulsed laser operation, Continuous wave operation, Q switched lasers, Erbium, Semiconductor lasers, Laser resonators, Laser dentistry, Q switches

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Proceedings Article | 7 March 2019 Paper

Temperature influence on spectroscopic and laser properties of Er:YLF crystal

Richard Švejkar, Jan Šulc, Helena Jelínková, Miroslav Čech

Proceedings Volume 10896, 108961L (2019) https://doi.org/10.1117/12.2506384

KEYWORDS: Continuous wave operation, Crystals, Erbium, Laser dentistry, Laser spectroscopy, Absorption, Pulsed laser operation, Laser crystals

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Proceedings Article | 15 February 2018 Paper

Spectroscopy and lasing of Tm:SrMoO4 crystal near 1.5, 1.9, and 2.3-um under 793-nm excitation

Jan Šulc, Richard Švejkar, Michal Němec, Maxim Doroshenko, Helena Jelínková, Liudmila Ivleva, Elizaveta Dunaeva

Proceedings Volume 10511, 1051125 (2018) https://doi.org/10.1117/12.2289513

KEYWORDS: Crystals, Thulium, Spectroscopy, Laser crystals, Luminescence, Absorption

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Proceedings Article | 15 February 2018 Paper

Temperature influence on spectroscopic properties and 2.7-μm lasing of Er:YAP crystal

Richard Švejkar, Jan Šulc, Michal Němec, Helena Jelínková, Karel Nejezchleb, Miroslav Čech

Proceedings Volume 10511, 1051121 (2018) https://doi.org/10.1117/12.2287138

KEYWORDS: Crystals, Erbium, Continuous wave operation, Luminescence, Absorption, Spectroscopy, Pulsed laser operation, Semiconductor lasers, Temperature metrology, Laser crystals

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Proceedings Article | 1 December 2017 Paper

Cryogenic-cooled Tm:SBN tunable laser

Richard Švejkar, Jan Šulc, Michal Němec, Helena Jelínková, Maxim Doroshenko, Alexander Papashvili, Pavel Lykov, Liudmila Ivleva

Proceedings Volume 10603, 1060305 (2017) https://doi.org/10.1117/12.2292425

KEYWORDS: Thulium, Luminescence, Crystals, Absorption, Semiconductor lasers, Laser crystals, Tunable lasers, Laser spectroscopy, Spectroscopy, Temperature metrology

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Proceedings Article | 11 May 2017 Presentation + Paper

Effect of cryogenic temperature on spectroscopic and laser properties of Er, Yb-doped potassium-lanthanum phosphate glass

Richard Švejkar, Jan Šulc, Michal Němec, Helena Jelínková, Karel Nitsch, Antonín Cihlář, Robert Král, Karel Nejezchleb, Martin Nikl

Proceedings Volume 10238, 102380V (2017) https://doi.org/10.1117/12.2264673

KEYWORDS: Potassium, Luminescence, Semiconductor lasers, Absorption, Laser damage threshold, Glasses, Laser spectroscopy, Temperature metrology, Spectroscopy, Cryogenics, Erbium, Ytterbium, High power lasers, Laser development

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Glass matrix doped with rare-earth ions is a promising laser active medium for high power laser systems. Due to amorphous structure of glasses the absorption and emission spectra lines are broader in comparison with crystalline materials thus pumping radiation can be absorbed efficiently, moreover much broader gain bandwidth is suitable for generation of ultra-short pulses. Another advantage of the glass matrix is the possibility to fabricate large volume ingots and simultaneously preservation of sufficient optical quality. The lower thermal conductivity of glasses can be compensated by geometry of the active medium for instance shaped into fibres or discs. We present temperature dependence of spectroscopic and laser properties of newly developed Er, Yb - doped potassium-lanthanum phosphate glass, which is appropriate for generation of radiation at 1.53 μm. The sample of Er,Yb:KLaP glassy mixture was cut into disc shape with dimensions of 2.5 mm (thickness) and 5 mm (diameter) and its faces were polished plan-parallelly without being anti-reflection coated. The temperature dependence of the transmission and emission spectra Er,Yb:KLaP together with the fluorescence decay time were measured the temperature range from 80 to 400 K. The fluorescence lifetime of manifold ⁴I_13/2(upper laser level) prolonged and the intensity of up-conversion radiation decreased with decreasing temperature. The longitudinal excitation of Er,Yb:KLaP was carried out by a fibre-coupled laser diode (pulse duration 2 ms, repetition rate 10 Hz, pump wavelength 969 nm). Laser resonator was hemispherical, with flat pumping mirror (HR @ 1.5 μm) and spherical output coupler (R = 98 % @ 1.5 - 1.6 μm). The Er,Yb:KLaP glass laser properties were investigated in the temperature range 80 - 300 K. The highest slope efficiency with respect to absorbed pumped power was 6.1 % at 80 K. The maximum output of peak amplitude power was 0.71 W at 80 K, i.e. 1.2 times higher than at 300 K. Tunability of laser wavelength at 80 K in range 1528 - 1552 nm was obtained using MgF₂ birefringent filter. From our measurement it can be concluded, that spectroscopic and laser properties of newly developed Er,Yb:KLaP glass are slightly temperature dependent.

SPIE Journal Paper | 5 April 2016

Phosphate content influence on structural, spectroscopic, and lasing properties of Er,Yb-doped potassium-lanthanum phosphate glasses

Jan Šulc, Richard Švejkar, Helena Jelínková, Karel Nejezchleb, Karel Nitsch, Antonín Cihlár, Robert Král, Martin Ledinsky, Antonn Fejfar, Miroslava Rodov, Petra Zemenová, Martin Nikl

OE, Vol. 55, Issue 04, 047102, (April 2016) https://doi.org/10.1117/12.10.1117/1.OE.55.4.047102

KEYWORDS: Glasses, Absorption, Erbium, Spectroscopy, Luminescence, Ions, Ytterbium, Raman spectroscopy, Semiconductor lasers, Laser damage threshold

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Proceedings Article | 16 March 2016 Paper

Effect of cryogenic temperature on spectroscopic and laser properties of Er,La:SrF2-CaF2 crystal

Richard Švejkar, Jan Šulc, Michal Němec, Helena Jelínková, Maxim Doroshenko, Andrei Nakladov, Vjatcheslav Osiko

Proceedings Volume 9726, 97261C (2016) https://doi.org/10.1117/12.2208569

KEYWORDS: Laser spectroscopy, Spectroscopy, Crystals, Laser crystals, Erbium lasers, Temperature metrology, Luminescence, Cryogenics, Erbium, Absorption, Laser resonators, Pulsed laser operation

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Proceedings Article | 20 February 2015 Paper

Temperature influence on diode pumped Er:CaF2 laser

Jan Šulc, Richard Švejkar, Michal Němec, Helena Jelínková, Maxim Doroshenko, Pavel Fedorov, Vyacheslav Osiko

Proceedings Volume 9342, 93421S (2015) https://doi.org/10.1117/12.2077454

KEYWORDS: Semiconductor lasers, Ceramics, Temperature metrology, Diodes, Luminescence, Laser damage threshold, Absorption, Laser applications, Mirrors, Output couplers

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Proceedings Article | 1 May 2014 Paper

Er-doped ortho- and metha-phosphate glassy mixtures for 1.54 μm laser construction

Jan Šulc, Richard Švejkar, Michal Němec, Helena Jelínková, Karel Nitsch, Antonín Cihlář, Robert Král, Karel Nejezchleb, Miroslava Rodová, Martin Nikl

Proceedings Volume 9135, 91351T (2014) https://doi.org/10.1117/12.2051209

KEYWORDS: Absorption, Luminescence, Semiconductor lasers, Glasses, Spectroscopy, Pulsed laser operation, Diodes, Ytterbium, Laser damage threshold, Potassium

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Showing 5 of 15 publications

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