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Absorption spectrum of 450 ppm Bismuth-doped pure silica sol-gel preform in the spectral region of 300-750 nm.
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Optical properties of a Bismuth-doped pure silica sol-gel core photonic crystal fiber (PCF) were investigated. We report on the absorption, CW luminescence and time resolved luminescence spectra at different excitation wavelengths at room temperature. Complex structure of the energy levels of Bismuth-connected centers in pure silica glass is put in...
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Context 1
... process of monolithic Bismuth-doped sol-gel preform preparation was similar to the one described in our recent article [5]. In present experiment, Bismuth concentration in silica glass was increased up to 300 ppm. As an illustration, optical absorption of a 450 ppm Bismuth-doped sol-gel preform sintered at 1300 • C is shown in Fig. 1. As can be seen, the absorption spectrum is similar to the one presented in reference [5] and puts in evidence two main absorption bands centered around 380 nm and 420 nm. It appears that these bands are a complex bands composed of three sub-bands as it is suggested by the Gaussian multi-peak fit shown in Fig. 1 (here the background ...
Context 2
... sintered at 1300 • C is shown in Fig. 1. As can be seen, the absorption spectrum is similar to the one presented in reference [5] and puts in evidence two main absorption bands centered around 380 nm and 420 nm. It appears that these bands are a complex bands composed of three sub-bands as it is suggested by the Gaussian multi-peak fit shown in Fig. 1 (here the background absorption was fitted as a polynome of third ...
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Citations
... Core and cladding absorption spectra of the developed BDF depicted in Fig. 1(b) were measured by a standard cut-back technique. The core absorption spectrum consisted of a series of bands in the near-IR and visible spectral regions that were definitely attributed to BACs associated with silicon atoms (BACs-Si) [12][13][14]. This type of fiber is characterized by a very low unsaturable loss near 1400 nm which is ≈ 2% with relation to the total absorption. ...
For the first time, to the best of the authors’ knowledge, a cladding-pumped bismuth-doped fiber laser (BDFL) is demonstrated. A “home-made” Bi-doped germanosilicate fiber with a 125 µm circular outer cladding made of fused silica and coated by a low refractive index polymer is used as an active medium pumped by commercial multimode laser diodes with a total output power of 25 W at 808 nm. We find that the BDFL with a free-running cavity (when feedback is provided by ≈4% back reflection from two bare right-angle cleaved fiber ends) composed of a 100-m-long bismuth-doped fiber is capable of emitting at a wavelength of 1440 nm. A slope efficiency of 0.5% with respect to the absorbed pump power with a maximum output power of ≈50 mW is obtained in a BDFL with a cavity formed by a highly reflective Bragg grating at 1461 nm and a right-angle cleaved fiber end. The beam quality factors (M²) of the output BDFL in the horizontal and vertical directions are measured to be 1.18 and 1.13, respectively. The processes affecting the efficiency of the BDFLs are also discussed. The possible improvements for the output power scaling and increasing the efficiency of the cladding-pumped BDFLs are proposed.
... Moreover, the doping concentration is seriously limited by the adsorptive capacity of the soot layer. In the past decade, researchers have been making great efforts on these difficulties and proposed some new methods to fabricate Bi-doped silica glass, such as nano-porous glass (NPG) fabrication [17] and sol-gel process [18] . Among these new methods, the melt-quenching method is outstanding to prepare highly uniform and heavily doped Bi glasses and fibers [19,20] . ...
... Among these new methods, the melt-quenching method is outstanding to prepare highly uniform and heavily doped Bi glasses and fibers [19,20] . However, the emission FWHMs of Bidoped silica glass or fibers fabricated by the above methods are below 300 nm [17,18,21,22] . The broader band needs to be extended for future transmission in the age of big data. ...
... The emission peak wavelength was at 1249 nm (Bi þ ∶ 3 P 1 → 3 P 0 [14] ) for 5 W pump power, corresponding to FWHM of 418 nm. It is much broader than those in silica glasses fabricated by other methods (262 nm in MCVD [14] , 263 nm in NPG [22] , and about 100 nm in sol-gel [18] ). The reason for such a broad bandwidth in our method might be attributed to the difference in the heat treatment history during the fabrication process for different methods [26,27] . ...
... 20 In particular, NIR-emitting Bi-doped glasses have been demonstrated in fabricating efficient all-fiber optical amplifiers and tunable fiber lasers. 21,22 Besides, various studies regarding the visible luminescence of Bi-doped materials have been also carried out for the production of adjustable lighting sources. [23][24][25] More attractively, it was reported by Zhou et al that an ultra-broadband emission covering the visible to NIR region continuously could be realized either within the nanocage structure in porous silica glass or by the femtosecond laser irradiation, originating from the simultaneous stabilization of multivalent Bi centers (Bi + , Bi 2+ , and Bi 3+ ) in such conditions. ...
The design of functional materials with tunable broadband luminescence performance is still of great interest in the fields of lighting, solar cells, tunable lasers, and optical amplifiers. Here, via a melt‐quenching method, a series of bismuth (Bi)‐doped germanium‐borate glasses with composition of 40GeO2–25B2O3–25Gd2O3–10La2O3–xBi2O3 have been prepared, in which multiple Bi active centers can be stabilized simultaneously. Dual‐modulating modes of visible (380‐750 nm) and near‐infrared (NIR) (1000‐1600 nm) broadband photoemissions were effectively controlled under flexible excitation scheme. Photoluminescence (PL) spectra at low temperature 10‐298 K were appropriately employed to interpret such an unusual wide visible emission band. To further illustrate the origin of NIR component, transmission electron microscopy (TEM) measurement was carried out. It is demonstrated experimentally that the visible emission mainly originates from the collective contribution of the ³P1/³P0→¹S0 transitions of Bi³⁺, while the broadband NIR luminescence should be related to the formation of low valent Bi⁺ and (or) Bi⁰ centers. This work may help to enhance the knowledge of the complex luminescence mechanism for the Bi species and it also enables such transparent glass materials to be a promising candidate for the multifunctional tunable light source.
... [16,17] Recently, we have reported the fabrication of Bi-doped silica and Bi/Al (or Ga)-codoped silica glasses using a novel solution doping technique based on binuclear or heterotrinuclear complexes and subsequent sintering. These glasses presented NIR luminescence associated with a single Si-BAC, [18] Al-BAC, [19] or Ga-BAC. [20] Another BAC related to phosphorus presents promising potential for the development of new tunable laser sources and amplifying media in the spectral range of the second telecommunication window. ...
Bismuth‐doped glasses are attractive materials for the development of new optical amplifiers and tunable laser sources. In this paper, Bi‐doped phosphosilicate glasses are prepared using the sol‐doping technique in combination with shaping using cold isostatic pressing. After a first drawing at high temperature (2000 °C), the obtained glass cane presents a wide near infrared (NIR) photoluminescence band under visible excitation. The authors show that this NIR optical activity, connected to phosphorus center, is preserved after a second drawing into a conventional optical fiber. These results confirm the potentialities of this synthesis approach for the fabrication of Bi‐activated optical fibers.
... The starting ∼300 ppm Bi doped silica was obtained by the basecatalysis sol-gel technique [18] and drawn to a microstructured optical fiber by the stack and draw process [31]. The different thermal steps applied to obtain the investigated fiber sample have been previously reported in Ref. [32]. This kind of sample has been employed since the microstructuration allows the light guiding effect in the core without adding other co-dopant. ...
We report an experimental investigation of the photoluminescence (PL) activities detected in as-drawn and γ-ray irradiated samples of a microstructured optical fiber elaborated with a silica-based core doped with Bismuth ions. The presence of several visible emission bands is revealed and characterized under 325 nm laser excitation. In both samples, four narrow emission bands are studied and analyzed. They are similarly bleached by a long UV laser exposure times. In addition, time-resolved luminescence data show that all these bands possess a similar lifetime of ∼4 μs Data analysis indicated that the energy levels scheme of the point defects responsible for these bands consists of: one above 5 eV, one at ∼3.6 eV, and at least one in the range 2.6–2.8 eV and of the ground one. As a consequence, even if the exact structural model cannot yet be fully identified, we suggest that the bands originate from color centers related to the Bismuth ions.
... In this Section we are interested in Bismuth-doped silica glass without other co-dopant. The first experimental investigation of photoluminescence in Bi-doped pure SiO 2 bulk glass was performed at low temperature [23], then soon after that, the photonic crystal fiber [29] and fibers fabricated by the powder-in-tube technique [30] were prepared and investigated at room temperature. Later the useful experimental data were reported in the subsequent works [7,31], in which the three-dimensional excitation-emission plots were constructed for different silica-based Bismuth-doped materials. ...
... In this material, six absorption and excitation bands were reported previously [7,23,29,33]. Their energies positions (wavelengths) were collected in the first two columns of Table 1. ...
Bismuth-doped silica-based glasses have already been proved to be promising materials for the fiber lasers and amplifiers operating in the near-infrared (NIR) spectral region. However, the development of such devices, which would have eligible efficiency, is impossible without a solid understanding of the NIR emitting center's nature. In the present work, based on the crystal field calculations we demonstrate that in silica and germanosilicate glasses this center is a univalent Bi ion affected by a rather strong local crystal field. According to our results, a transition from the first excited state to the ground state in Bi+ causes the famous NIR photoluminescence. The relatively high degree of reduction of the spin-orbit coupling constant indicates, most probably, the formation of weak covalent bonding of Bi+ with ions of the environment.
... The Bismuth-doped silica optical fiber investigated in the present study is a photonic crystal fiber having a core diameter of~6.4 μm [23]. The starting high-purity Bi-doped silica glass, used as core material, was produced by sol-gel technique [24] with a Bi content of 300 ppm, evaluated by EPMA (electron probe micro-analysis). ...
... The microstructured fiber was fabricated by stack and draw process [25]. Further details regarding the different steps of the fiber production are available in [23,24]. ...
We report an experimental investigation focused on the green emission detected in γ-ray irradiated Bismuth-doped photonic crystal fibers. Our photoluminescence spectra, recorded at room temperature, provide evidence for the presence of two emission bands both located at ∼. 530. nm (2.34. eV). One emission is detected only in the Bi-doped core while the other, is detected in the cladding. These two emissions feature different excitation spectra and a fast and a slow decay lifetime. The origin of the fast emission decay, about ten nanoseconds, is tentatively attributed to a silica intrinsic defect, whereas the slow component, having lifetime of about 2. μs and featuring anti-stokes emission, is certainly caused by Bi related defects.
... Contrarily to these materials, the SiO 2 glasses, with bismuth as the single dopant display the very distinct NIR photoluminescence with the emission maxima at 830 and 1430 nm [5,[7][8][9][10][11][12][13][14]. The respective photoluminescence excitation spectra display maxima at 1420, 820, 420, 370 and 240 nm (emission at 1430 nm) or 820 and 420 nm (emission at 830 nm) [11,14]. ...
... The respective photoluminescence excitation spectra display maxima at 1420, 820, 420, 370 and 240 nm (emission at 1430 nm) or 820 and 420 nm (emission at 830 nm) [11,14]. The detailed discussion on the spectral properties of this luminescent center can be found elsewhere [8][9][10][11][12][13][14]. The similar NIR PL was also observed in SiO x N y siliconoxynitride glass films [15]. ...
... The NIR PL spectra for the both specimens and 690 nm afforded no detectable NIR PL. It is evident, that the emission maxima and its excitation profiles matches well the corresponding properties of NIR PL centers in SiO 2 glass with bismuth as the single dopant [7][8][9][10][11][12][13]. ...
Near infrared photoluminescent bismuth(I) silanolate centers ((≡Si-O)3Si–O-Bi) were prepared on the surface of SiO2 xerogel, by the treatment in the vapors of bismuth(I) chloride. The optical properties of these groups are almost identical to that of photoluminescent centers in the bulk SiO2 glasses with bismuth as the single dopant.
... A separate point of interest regarding BDFs is impact of heating above room temperature (25°C, further -RT) and pump wavelength's variation upon their absorptive and fluorescent properties; see e.g. Refs [1,4,[9][10][11][12][13][14][15]. To-date, different kinds of the effect of temperature on basic parameters of BDFs with different core compositions and light sources built on their base have been reported. ...
We report an experimental analysis of attenuation and fluorescence (at low-power 750-nm excitation) spectra’ transformations in yttria-alumino-silicate fiber doped with Bismuth (Bi), which occur at higher than room, but not exceeding 700°C, temperatures. As well, we address impact of elevating temperature upon the fiber’s basic characteristics, such as fluorescence/resonant-absorption saturation, fluorescence lifetime, and pump-light backscattering, given by the presence of Bi-Al related active centers (BACs). The experimental data reveals dramatic impact of heating and high-temperature annealing in excess of 500…550°C on the fiber’s state-of-the-art, expressed as significant rise of resonant absorption, enhancement of BACs NIR fluorescence, and reduction of scattering loss. In the meantime, such microscopic parameters of the fiber as BACs fluorescence lifetime and saturation power are found to be kept almost unchanged in its post-annealed state as compared to the pristine one. Possible mechanisms responsible for the phenomena and advantages of utilizing temperature-treated fiber of such type for lasing/amplifying purposes are discussed.
... Unfortunately, the nature of BACs in different glass hosts responsible for the broadband fluorescence is not yet understood. A separate point of interest regarding BDFs is the effect of temperature [9]- [12] and pump wavelength's variation [1], [4], [9], [13], [14] upon the absorptive and fluorescent properties. It also deserves mentioning that the metastable level's lifetime of BACs in BDFs with different host compositions and at different BACs concentrations varies from $0.6 to $1 s at room temperature [1] and that it decreases with a temperature increase [12]. ...
Yttria-alumino-silicate fibers heavily doped with bismuth (BI) are investigated
for fluorescence temperature sensing within the interval 25 �C. . . 500 �C at 750-nm
(LED) excitation. High doping with Bi which resulted in a high concentration of Bi active
(fluorescing) centers, is shown to permit the use of short pieces of the fibers as “point”
sensors, which is advantageous for applications. Theoretical backgrounds of three commonly
utilized sensing techniques, based on measuring fluorescence intensity ratio, fluorescence
lifetime, and frequency-domain referencing, are developed and compared,
aiming for effective temperature sensing using these fibers.
