Tm3+/Ho3+ co-doped germanate glass and double-clad optical fiber for broadband emission and lasing above 2 μm

In this paper, a 2 μm broadband emission under 796 nm laser diode excitation in low phonon energy GeO2-Ga2O3-BaO glass system is co-doped with 0.7Tm2O3/(0.07-0.7)Ho2O3 (mol%). The widest emission band (where the Tm3+ → Ho3+ energy transfer efficiency is 63%) was obtained for 0.7Tm2O3/0.15Ho2O3 co-doped glass from which a double-clad optical fiber was realized and investigated. Optimization of Tm3+/Ho3+ concentration enabled the acquisition of broadband amplified spontaneous emission (ASE) in double-clad optical fiber with a full width at half maximum (FWHM): 377 nm and 662 nm for 3 dB and 10 dB bandwidth, respectively. ASE spectrum is a result of the superposition of (Tm3+: 3H4 →Η3F4) 1.45 μm, (Tm3+: 3F4 → 3H6) 1.8 μm and (Ho3+:5I7 → 5I8) 2 μm emission bands. Hence, highly rare-earth co-doped germanate glass is characterized by a remarkably broader ASE spectrum than silica and tellurite fibers showed promising lasing properties for their further application in tunable and dual wavelength lasers

Optical characterization of nano- and microcrystals of EuPO4 created by one-step synthesis of antimony-germanate-silicate glass modified by P2O5

Technology of active glass-ceramics (GC) is an important part of luminescent materials engineering. The classic method to obtain GC is based on annealing of parent glass in proper temperature and different time periods. Generally, only the bulk materials are investigated as a starting host for further applications. However, the effect of an additional heat-treatment process on emission and structural properties during GC processing is omitted. Here, we focus on the possibility of obtaining transparent glass-ceramic doped with europium ions directly with a melt-quenching method. The influence of phosphate concentration (up to 10 mol %) on the inversion symmetry of local environment of Eu3+ ions in antimony-germanate-silicate (SGS) glass has been investigated. The Stark splitting of luminescence spectra and the local asymmetry ratio estimated by relation of (5D0→7F2)/(5D0→7F1) transitions in fabricated glass confirms higher local symmetry around Eu3+ ions. Based on XRD and SEM/EDX measurements, the EuPO4 nano- and microcrystals with monoclinic geometry were determined. Therefore, in our experiment, we confirmed possibility of one-step approach to fabricate crystalline structures (glass-ceramic) in Eu-doped SGS glass without additional annealing process

Spectroscopic properties of erbium-doped oxyfluoride phospho-tellurite glass and transparent glass-ceramic containing BaF2 nanocrystals

The ErF3-doped oxyfluoride phospho-tellurite glasses in the (40-x) TeO2-10P2O5-45 (BaF2-ZnF2) -5Na2O-xErF3 system (where x = 0.25, 0.50, 0.75, 1.00, and 1.25 mol%) have been prepared by the conventional melt-quenching method. The effect of erbium trifluoride addition on thermal, structure, and spectroscopic properties of oxyfluoride phospho-tellurite precursor glass was studied by differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR), and Raman spectroscopy as well as emission measurements, respectively. The DSC curves were used to investigate characteristic temperatures and thermal stability of the precursor glass doped with varying content of ErF3. FTIR and Raman spectra were introduced to characterize the evolution of structure and phonon energy of the glasses. It was found that the addition of ErF3 up to 1.25 mol% into the chemical composition of phospho-tellurite precursor glass enhanced 2.7 µm emission and upconversion. By controlled heat-treatment process of the host glass doped with the highest content of erbium trifluoride (1.25 mol%), transparent erbium-doped phospho-tellurite glass-ceramic (GC) was obtained. X-ray diffraction analysis confirmed the presence of BaF2 nanocrystals with the average 16 nm diameter in a glass matrix. Moreover, MIR, NIR, and UC emissions of the glass-ceramic were discussed in detail and compared to the spectroscopic properties of the glass doped with 1.25 mol% of ErF3 (the base glass)

Fluoroindate glass co-doped with Yb3+/Ho3+ as a 2.85 μm luminescent source for MID-IR sensing

This work reports on the fabrication and analysis of near-infrared and mid-infrared luminescence spectra and their decays in fluoroindate glasses co-doped with Yb3+/Ho3+. The attention has been paid to the analysis of the Yb3+ ! Ho3+ energy transfer processed ions in fluoroindate glasses pumped by 976 nm laser diode. The most effective sensitization for 2 um luminescence has been obtained in glass co-doped with 0.8YbF3/1.6HoF3. Further study in the midinfrared spectral range (2.85 um) showed that the maximum emission intensity has been obtained in fluoroindate glass co-doped with 0.1YbF3/1.4HoF3. The obtained efficiency of Yb3+ ! Ho3+ energy transfer was calculated to be up to 61% (0.8YbF3/1.6HoF3), which confirms the possibility of obtaining an efficient glass or glass fiber infrared source for a MID-infrared (MID-IR) sensing application

Phase-locking of 19-core Yb3+ - doped optical fibre

The supermode generation in a multicore optical fibre laser can be realised by phase-locking of radiation inside of the fibre. The model proposed by authors implies the achievement of supermode generation by exchanging radiation between the cores during the development of the laser action. The analysis of the impact of coupling value between the cores on phase radiation of particular emitters was considered. In the paper the phase-locking of 19-core optical fibre doped with Yb3+ ions is presented. The analysis of material and geometrical parameters of the active 19 -core optical fibre and phase deviation on the beam quality factor of the laser beam in the far-field diffraction region has been analysed. The beam quality factor of the manufactured multicore fibre equals BQF = 0.71, V = 2.4, d = 18 ěm. As a result of the conducted analysis a double-clad 19 – cores optical fibre doped with ytterbium ions has been designed and fabricated and its luminescence spectra and far-field diffraction pattern have been measured. Registered in the experiment in MOFPA system far-field pattern showed centrally located peak of relatively high radiation intensity together with smaller side-lobes, and as such was similar to the pattern which had been obtained numerically

Luminescence properties of special fibres

W artykule przestawiono wyniki prac nad zastosowaniem dwóch nowych typów światłowodów domieszkowanych jonami ziem rzadkich do budowy laserów włóknowych. Jednym z nich, są światłowody wielordzeniowe umożliwiające uzyskanie wiązki laserowej o dużej mocy i małej rozbieżności (supermodu). Drugi prezentowanym rozwiązaniem są światłowody, w których ukształtowany w spiralę rdzeń zapewnia silną absorpcję pompy, jak również łatwe jej odsprzężenie na wyjściu światłowodu od generowanego w rdzeniu promieniowania. Wytworzono oba rodzaje światłowodów domieszkowanych jonami Nd3+ oraz określono ich właściwości luminescencyjne.The high power, short pulse generation in a fibre lasers is limited by nonlinear effects (Raman and Brillouin scattering, self - phase modulation). Therefore it's necessary to find innovative constructions of rare-earth doped optical fibres considerably different from conventional double-clad optical fibres. In the paper the possibility of applying new optical fibers as an active material for constructing high-power fiber lasers is presented. Multicore active optical fibre is one of new construction. Such a fibre enables attaining a high-intensity and low-divergence laser beam (supermod) in the far-field diffraction region (Fig. 2, 4). Second type of new active optical fibre is helical - core optical fibre. Due to a specific shape of the core such fibre is characterized by effective absorption of pump radiation.Moreover, optimization of material and geometrical optical fibre properties enables to increase volume of active material (core diameter) while single mode operation is preserved. The luminescence spectra of both types of manufactured optical fibres doped with Nd3+ are presented (Fig. 7, 8, 12)

Capillary sensor with samarium doped core

W artykule przedstawiono czujnik światłowodowy wykorzystujący szklane włókno kapilarne, wyposażone w luminescencyjny rdzeń. Na rdzeń światłowodu zaproponowano szkło krzemianowe domieszkowane jonami samaru, zapewniające selektywną absorpcję promieniowania w zakresie 550-720 nm. Konstrukcja czujnika pozwala na pomiar stężenia roztworów, zaprezentowany na przykładzie roztworu Rodaminy B (RhB) w zakresie stężeń 0,01 - 0,15% ww. W wyniku metody sumowania sygnałów z dwóch pasm luminescencji uzyskano czułość pomiaru na poziomie -275•103 %-1. Otrzymane wyniki wskazują, że opracowana konstrukcja optrody może posłużyć jako kompaktowy czujnik luminescencyjny do ciągłego pomiaru właściwości roztworów.The paper presents optical fiber sensor based on an optical fiber capillary with a luminescent side ribbon. Siliceous core was doped with Sm3+ ions which ensure multi colour luminescence in visible spectrum (550-720 nm). The special fibre construction allows to measure concentration of Rhodamine B (RhB) solution in rage of 0.01 - 0.15% ww. The sensitivity was obtained by using combination of measurements at 564 nm and 601 nm wavelengths and it reached -275•103 %-1. The use of certain wavelengths at measurement procedure allows to obtain the increase of selectivity and sensitivity of optrode. The results allow to reach the conclusion that the designed optrode has the ability to be used for construction of compact luminescent sensors, measuring selected properties of the solutions