Research

8 pages, 1208 KiB

Open AccessArticle

by Lam Thi Ngoc Tran, Damiano Massella, Lidia Zur, Alessandro Chiasera, Stefano Varas, Cristina Armellini, Giancarlo C. Righini, Anna Lukowiak, Daniele Zonta and Maurizio Ferrari

Appl. Sci. 2018, 8(8), 1335; https://doi.org/10.3390/app8081335 - 10 Aug 2018

Cited by 26 | Viewed by 4715

Abstract

The development of efficient luminescent systems, such as microcavities, solid-state lasers, integrated optical amplifiers, and optical sensors is the main topic in glass photonics. The building blocks of these systems are glass-ceramics activated by rare-earth ions because they exhibit specific morphologic, structural, and [...] Read more.

The development of efficient luminescent systems, such as microcavities, solid-state lasers, integrated optical amplifiers, and optical sensors is the main topic in glass photonics. The building blocks of these systems are glass-ceramics activated by rare-earth ions because they exhibit specific morphologic, structural, and spectroscopic properties. Among various materials that could be used as nanocrystals to be imbedded in a silica matrix, tin dioxide presents some interesting peculiarities, e.g., the presence of tin dioxide nanocrystals allows an increase in both solubility and emission of rare-earth ions. Here, we focus our attention on Er³⁺—doped silica—tin dioxide photonic glass-ceramics fabricated by a sol-gel route. Although the SiO₂-SnO₂:Er³⁺ could be fabricated in different forms, such as thin films, monoliths, and planar waveguides, we herein limit ourselves to the monoliths. The effective role of tin dioxide as a luminescence sensitizer for Er³⁺ ions is confirmed by spectroscopic measurements and detailed fabrication protocols are discussed. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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13 pages, 1692 KiB

Open AccessArticle

Investigation of Population Dynamics in 1.54-μm Telecom Transitions of Epitaxial (Er_xSc_1-x)₂O₃ Thin Layers for Coherent Population Manipulation: Weak Excitation Regime

by Satoru Adachi, Yoshihiro Kawakami, Reina Kaji, Takehiko Tawara and Hiroo Omi

Appl. Sci. 2018, 8(6), 874; https://doi.org/10.3390/app8060874 - 25 May 2018

Cited by 2 | Viewed by 2449

Abstract

We have investigated the energy transfers in the 1.54-

μ

m region of (Er,Sc)

_{2}

O

_{3}

epitaxial thin films grown on Si(111). The interplay of the energy transfers between Er ions in the different and the same symmetry sites makes the dynamics [...] Read more.

We have investigated the energy transfers in the 1.54-

μ

m region of (Er,Sc)

_{2}

O

_{3}

epitaxial thin films grown on Si(111). The interplay of the energy transfers between Er ions in the different and the same symmetry sites makes the dynamics complicated. To suppress the energy transfer upconversion, low power and resonant excitation of the third crystal-field level (

^{4} I_{13 / 2} : Y_{3}^{'}

) of the Er

^{3 +}

site with

C_{3 i}

symmetry was employed. The time-resolved photoluminescence measurements of the

Y_{1}^{'}

-

Z_{1}^{'}

transition indicate the existence of two decay components having fast (10–100

μ

s) and slow (0.1–1 ms) relaxation times in the range of 4–60 K. The model calculation including the inter-site energy transfers, the temperature-sensitive and -insensitive non-radiative relaxations fits the experimental results well. Moreover, the long averaged inter-Er

^{3 +}

distance obtained by decreasing Er concentration was found to reduce two kinds of non-radiative relaxation rates and the energy transfer rates between Er ions very effectively. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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11 pages, 3193 KiB

Open AccessArticle

40 W All-Fiber Er/Yb MOPA System Using Self-Fabricated High-Power Passive Fiber Components

by Pawel Kaczmarek, Dorota Stachowiak and Krzysztof M. Abramski

Appl. Sci. 2018, 8(6), 869; https://doi.org/10.3390/app8060869 - 25 May 2018

Cited by 10 | Viewed by 5662

Abstract

In this work, we demonstrate a three-stage all-fiber master oscillator power amplifier (MOPA) system emitting over 40 W of continuous-wave (CW) output power at ~1.5 µm. The setup utilizes three self-fabricated high-power passive fiber components: a mode-field adaptor (MFA) and two types of [...] Read more.

In this work, we demonstrate a three-stage all-fiber master oscillator power amplifier (MOPA) system emitting over 40 W of continuous-wave (CW) output power at ~1.5 µm. The setup utilizes three self-fabricated high-power passive fiber components: a mode-field adaptor (MFA) and two types of pump and signal power combiners. Their development allowed us to become independent from commercially available components, which are often incompatible with fibers used in the experimental setups, resulting in additional losses. A power combiner with single-mode (SM) signal fibers in a configuration (5 + 1) × 1 was used in the second stage of the MOPA system, which was based on an SM Er–Yb co-doped double-clad (DC) fiber. The fabricated MFA was used to connect the second amplifier stage based on SM fibers with the third amplifier stage based on large-mode-area (LMA) fibers. In the third stage of MOPA system, based on Er–Yb LMA DC fibers, we used the fabricated power combiner based on LMA-type signal fibers in a configuration (6 + 1) × 1. The presented three-stage MOPA system, utilizing self-fabricated high-power passive fiber components, enables amplification of an input signal of 10 mW up to 44 W of the CW power at the wavelengths of 1555 nm and 1563 nm, corresponding to a gain level of approximately 36.4 dB. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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12 pages, 3968 KiB

Open AccessArticle

YAG Ceramic Nanocrystals Implementation into MCVD Technology of Active Optical Fibers

by Jan Mrázek, Ivan Kašík, Lenka Procházková, Václav Čuba, Vladimír Girman, Viktor Puchý, Wilfried Blanc, Pavel Peterka, Jan Aubrecht, Jakub Cajzl and Ondřej Podrazký

Appl. Sci. 2018, 8(5), 833; https://doi.org/10.3390/app8050833 - 21 May 2018

Cited by 19 | Viewed by 4814

Abstract

Nanoparticle doping is an alternative approach the conventional solution doping method allowing the preparation of active optical fibers with improved optical and structural properties. The combination of the nanoparticle doping with MCVD process has brought new technological challenges. We present the preparation of [...] Read more.

Nanoparticle doping is an alternative approach the conventional solution doping method allowing the preparation of active optical fibers with improved optical and structural properties. The combination of the nanoparticle doping with MCVD process has brought new technological challenges. We present the preparation of fiber lasers doped with Er-doped yttrium aluminum garnet (Er:YAG) nanocrystals. These nanocrystals, prepared by a hydrothermal reaction, were analyzed by several structural methods to determine the mean nanocrystal size and an effective hydrodynamic radius. The nanocrystals were incorporated into silica frits with various porosity made by the conventional MCVD process. The Er:YAG-doped silica frits were processed into preforms, which were drawn into optical fibers. We studied the effect of the nanocrystal size and frit’s porosity on the final structural and optical properties of prepared preforms and optical fibers. Selected optical fibers were tested as an active medium in a fiber ring laser setup and the characteristics of the laser were determined. Optimal laser properties were achieved for the fiber length of 7 m. The slope efficiency of the fiber laser was about 42%. Presented method can be simply extended to the deposition of other ceramic nanomaterials. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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13 pages, 2553 KiB

Open AccessArticle

Numerical Analysis of Q-Switched Erbium Ion Doped Fluoride Glass Fiber Laser Operation Including Spontaneous Emission

by Sławomir Sujecki

Appl. Sci. 2018, 8(5), 803; https://doi.org/10.3390/app8050803 - 16 May 2018

Cited by 10 | Viewed by 3347

Abstract

Partial differential equations are solved to perform a spatiotemporal analysis of Q-switched operation of a fluoride fiber laser doped with erbium ions. A method of lines is applied in order to reduce the partial differential equations to a set of ordinary differential equations. [...] Read more.

Partial differential equations are solved to perform a spatiotemporal analysis of Q-switched operation of a fluoride fiber laser doped with erbium ions. A method of lines is applied in order to reduce the partial differential equations to a set of ordinary differential equations. The latter set is then solved using an algorithm designed for a solution of stiff equation problems. A spontaneous emission term is added to equations that model the dynamics of the photon population within the laser cavity for the infrared signal wave. The results show that, without an inclusion of the spontaneous emission term, the correct behavior of the photon population and energy level populations cannot be reproduced. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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10 pages, 2881 KiB

Open AccessArticle

Nanocomposite Antimony-Germanate-Borate Glass Fibers Doped with Eu³⁺ Ions with Self-Assembling Silver Nanoparticles for Photonic Applications

by Jacek Zmojda, Piotr Miluski and Marcin Kochanowicz

Appl. Sci. 2018, 8(5), 790; https://doi.org/10.3390/app8050790 - 15 May 2018

Cited by 5 | Viewed by 2960

Abstract

Recently, nanocomposite glass materials embedded with silver particles and lanthanide ions have been widely investigated. The main interest is a surface plasmon resonance (SPR) phenomenon, which, as a result of nanometric particles’ interaction with external electromagnetic waves, has led to the enhancement of [...] Read more.

Recently, nanocomposite glass materials embedded with silver particles and lanthanide ions have been widely investigated. The main interest is a surface plasmon resonance (SPR) phenomenon, which, as a result of nanometric particles’ interaction with external electromagnetic waves, has led to the enhancement of rare-earth luminescence. In most works, nanoparticles are created in photonic glass by annealing for various times; however, the most discussion of this field in the literature is dedicated to the practical use of plasmonic effect in optical fibers. In this paper, the effect of silver ions on the luminescent properties of europium ions in antimony-germanate-borate (SGB) glass fibers is presented. The glass was synthesized by a standard melt-quenching technique, and glass fiber was drowned at 580 °C. The analysis of Ag⁺ ions content, as well as heat-treatment (hT) time, show an increase of almost 36% in emissions at 616 nm for glass fiber co-doped with 0.1Ag⁺/0.2Eu³⁺ ions after a 2 h annealing process. In the experiment, the interaction mechanism was investigated in terms of localized SPR, in each step of the glass fiber fabrication process. Moreover, we demonstrate that the self-assembling of silver nanoparticles onto a glass fiber surface is possible only for fiber co-doped with 0.6Ag/0.2Eu ions. This non-conventional, bottom-up technique of thin film was analyzed by Scanning Electron Microscopy (SEM) measurements. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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10 pages, 1656 KiB

Open AccessArticle

Comparative Spectroscopic Investigation of Tm³⁺:Tellurite Glasses for 2-μm Lasing Applications

by Huseyin Cankaya, Adil Tolga Gorgulu, Adnan Kurt, Adolfo Speghini, Marco Bettinelli and Alphan Sennaroglu

Appl. Sci. 2018, 8(3), 333; https://doi.org/10.3390/app8030333 - 27 Feb 2018

Cited by 18 | Viewed by 2944

Abstract

We performed a comparative spectroscopic analysis on three novel Tm³⁺:tellurite-based glasses with the following compositions Tm₂O₃:TeO₂-ZnO (TeZnTm), Tm₂O₃:TeO₂-Nb₂O₅ (TeNbTm), and Tm³⁺:TeO₂-K₂ [...] Read more.

We performed a comparative spectroscopic analysis on three novel Tm³⁺:tellurite-based glasses with the following compositions Tm₂O₃:TeO₂-ZnO (TeZnTm), Tm₂O₃:TeO₂-Nb₂O₅ (TeNbTm), and Tm³⁺:TeO₂-K₂O-Nb₂O₅ (TeNbKTm), primarily for 2-μm laser applications. Tellurite glasses were prepared at different doping concentrations in order to investigate the effect of Tm³⁺ ion concentration as well as host composition on the stimulated emission cross sections and the luminescence quantum efficiencies. By performing Judd–Ofelt analysis, we determined the average radiative lifetimes of the ³H₄ level to be 2.55 ± 0.07 ms, 2.76 ± 0.03 ms and 2.57 ± 0.20 ms for the TeZnTm, TeNbTm and TeNbKTm samples, respectively. We clearly observed the effect of the cross-relaxation, which becomes significant at higher Tm₂O₃ concentrations, leading to the quenching of 1460-nm emission and enhancement of 1860-nm emission. Furthermore, with increasing Tm₂O₃ concentrations, we observed a decrease in the fluorescence lifetimes as a result of the onset of non-radiative decay. For the ³H₄ level, the highest obtained quantum efficiency was 32% for the samples with the lowest Tm₂O₃ ion concentration. For the 1860-nm emission band, the average emission cross section was determined to measure around 6.33 ± 0.34 × 10⁻²¹ cm², revealing the potential of thulium-doped tellurite gain media for 2-μm laser applications in bulk and fiber configurations. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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1340 KiB

Open AccessArticle

Effect of ZnO Addition and of Alpha Particle Irradiation on Various Properties of Er³⁺, Yb³⁺ Doped Phosphate Glasses

by Arun Poudel, Iuliia Dmitrieva, Regina Gumenyuk, Laura Mihai, Dan Sporea, Ofelia Mureşan, Ion Rusen, Teemu Hakkarainen, Nadia G. Boetti, Tapio Niemi and Laeticia Petit

Appl. Sci. 2017, 7(10), 1094; https://doi.org/10.3390/app7101094 - 24 Oct 2017

Cited by 8 | Viewed by 3807

Abstract

New Er³⁺, Yb³⁺ codoped phosphate glasses with the (98-x) (0.50P₂O₅-0.40SrO-0.10Na₂O) -0.5Er₂O₃-1.5Yb₂O₃-xZnO (in mol %) composition were prepared by melting process with up to 10 mol % [...] Read more.

New Er³⁺, Yb³⁺ codoped phosphate glasses with the (98-x) (0.50P₂O₅-0.40SrO-0.10Na₂O) -0.5Er₂O₃-1.5Yb₂O₃-xZnO (in mol %) composition were prepared by melting process with up to 10 mol % of ZnO. The impact of the changes in the glass composition on the thermal, optical, structural properties was investigated. Using IR and Raman spectroscopies, we confirmed that the addition of ZnO up to 10 mol % leads to a depolymerization of the network without having a significant impact on the Er³⁺ and Yb³⁺ sites. We also discuss the effect of alpha particles irradiation. The glass with 2.5 mol % of ZnO was irradiated with 3 MeV alpha particles and a total fluence of 10¹² α/cm². After irradiation, this glass exhibits surface expansion (measured at ~200 nm, 1.5 months after the irradiation) and an increase in the surface roughness. The alpha particles irradiation is suspected to lead to changes in the spectroscopic properties of the glass. Finally, the photo-response of the glass was found to be reversible. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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