Co-doped Silica Fiber Research Articles

Gamma irradiation-induced enhancement of Pb-related near-infrared luminescence in PbS/Al co-doped silica fiber.

The impact of Al co-doping and gamma irradiation (0.3-3 kGy) on the spectral properties of lead-related active centers (PACs) in PbS/Al co-doped silica fiber (PADF) has been studied. Distinct absorption peaks at 700 and 1030 nm, and photoluminescence at 1100 nm, originated from Al-related lead active center (PAC-Al). The luminescence intensity of PACs at 900 and 1150 nm increased with irradiation doses in PADF with 0.01 at% Al co-doping. Notably, after irradiation with a 0.5 kGy dose, over a 16 dB enhancement of luminescence from PAC-Al was observed in PADF doped with 0.1 at% Al under 980 nm pumping. The on-off gain of the PADF at 1100 nm increased ∼12 dB after irradiation with a dose of 0.3 kGy. It was found that PAC-Al was preferentially generated over PAC at 1150 nm in Al co-doped fibers under irradiation. The proposed underlying mechanism for photoluminescence enhancement is the irradiation-induced reduction of Pb ions and Al-related defects. PbS/Al co-doped silica fiber is a promising candidate for active fibers operating at ∼1100 nm.

Enhanced radiation resistance of Er3+/Yb3+ co-doped high-phosphorus silica glasses and fibers via phase-interface engineering

Enhanced radiation resistance of Er3+/Yb3+ co-doped high-phosphorus silica glasses and fibers via phase-interface engineering

A Radiation Dosimeter Based on Ce/Tb Co-Doped Silica Fiber for Radiotherapy Application

A Radiation Dosimeter Based on Ce/Tb Co-Doped Silica Fiber for Radiotherapy Application

High ytterbium concentration Yb/Al/P/Ce co-doped silica fiber for 1-µm ultra-short cavity fiber laser application.

We demonstrate a high ytterbium concentration Yb/Al/P/Ce co-doped silica fiber by conventional modified chemical vapor deposition (MCVD) technology and solution doping process. The fiber has a Yb concentration of about 2.5 wt%, and the corresponding core absorption coefficient is measured to be ∼1400 dB/m at 976 nm. The gain coefficient was measured to be approximately 1.0 dB/cm. It is found that the Yb/Al/P/Ce co-doped silica shows a lower photodarkening-induced equilibrium loss of 52 dB/m at 633 nm than the Yb/Al/P co-doped silica fiber of 117 dB/m. Using the heavily Yb3+-doped silica fiber, a compact and robust ultrashort cavity single-frequency fiber laser was achieved with a maximum output power of 75 mW and a linewidth of 14 kHz. Furthermore, a compact passively mode-locked fiber laser (MLFL) with a repetition rate of 1.23 GHz was also proposed using our developed Yb-doped fiber. The laser properties of the proposed lasers were systematically investigated, demonstrating the superior performance of this fiber in terms of photodarkening resistance and ultrashort-cavity laser application. Furthermore, utilizing an all-fiber structure based on silica-based fiber offers the significant advantage of high stability and reliability.

Hydrogen-Related Anti-Radiation Effect and Its Suppression Mechanism in Er3+/Al3+/Ge4+ Co-Doped Silica Fibers

The antiradiation effect and evolution process of color center defects in hydrogen-treated Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> /Al <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> /Ge <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> codoped fiber under radiation were studied. The radiation-induced absorption spectra and continuous wave electron paramagnetic resonance spectra of glass slice samples were tested to explain the mechanism of internal defect transformation. The hydrogen treatment reduces radiation-induced absorption and increases loss in the working band by the combination of the Ge-related short wavelength absorption edge effect and the absorption peak of hydrogen vibration. Thus, there is an optimal hydrogen concentration for decreasing the radiation-induced gain variation (RIGV) of optical fibers, and the fiber with 3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> hydrogen content had the lowest RIGV of approximately 0.038 dB/krad. The radiation-induced absorption and continuous wave electron paramagnetic property revealed that the hydrogen treatment suppresses Al-OHC and Ge dangling bands in optical fibers. Hydrogen also generates H(I), Si-E', and Ge-E' defects in the irradiation environment. This work helps to elucidate how hydrogen improves the radiation resistance of Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> /Al <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> /Ge <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> codoped silica fibers.

Exceeding 25 dB Gain Broad-Spectrum Amplification in L-Band Based on a Bi/Er/La Co-Doped Silica Fiber

Exceeding 25 dB Gain Broad-Spectrum Amplification in L-Band Based on a Bi/Er/La Co-Doped Silica Fiber

Enhanced fluorescence and gain characteristics of PbS doped silica fiber with PbSe nano-semiconductor co-doping

A PbS/PbSe nano-semiconductor co-doped silica fiber (PbS/PbSe DSF) was prepared and the enhancement mechanism of fluorescence and gain characteristics were investigated. PbS/PbSe DSF showed the broadband luminescence ranging from 1000 nm to 1380 nm, and the fluorescence intensity at 1160 nm and 1300 nm was enhanced by 15.8 dB and 14.6 dB, respectively. The on–off gain of PbS/PbSe DSF is 13.7–18.9 dB in the range of 1100–1350 nm and the net gain is 10.7–14.5 dB under 980 nm pumping. Simultaneously, based on density functional theory (DFT), local structural models of PbS/PbSe co-doped fiber materials were built, and the study showed that the introduction of PbSe increased the absorption at 969 nm and the corresponding emission in the range of 1100–1400 nm. Moreover, microstructural characterization showed the presence of high-density nanoparticle distribution in the core of PbS/PbSe DSF, indicating that the PbSe co-doping may have changed the local field environment of PbS deposition and increased the crystallinity, which finally improved the fiber performance. The results indicate that the proposed PbS/PbSe DSF is a potential gain material with important research value in areas such as active fiber amplifiers.

Enhanced Gain Characteristics of PbS-Doped Silica Fiber in O-Band by Co-Doping Er Ions

We report a novel PbS/Er co-doped silica fiber (PEDF) with improved spectral properties in O-band (1260–1360 nm). The results show that the gain of the PEDF exceeds 15 dB in the range of 1150–1360 nm. Compared to PbS-doped silica fiber, the PEDF has a gain improvement of 6.4–10.9 dB in O-band. In addition, the concentration of Pb and S in the PEDF core is significantly higher, and the size distribution of PbS nanoparticles is more concentrated in a narrow range. These factors may account for the enhanced gain characteristics of the PEDF. This work reveals the positive effect of co-doping Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions on the gain characteristics of the PEDF in O-band, and suggests an important research direction for the design of broadband amplifiers and light sources for optical communication with zero dispersion.

Near 0.5 dB gain per unit length in O-band based on a Bi/P co-doped silica fiber via atomic layer deposition.

In this work, bismuth doped fiber (BDF) and bismuth/phosphosilicate co-doped fiber (BPDF) were fabricated by atomic layer deposition (ALD) combined with the modified chemical vapor deposition (MCVD). The spectral characteristics are studied experimentally and the BPDF has good excitation effect covering the O band. A diode pumped BPDF amplifier with the gain over 20 dB from 1298-1348 nm (50 nm) has been demonstrated. The maximum gain of 30 dB was measured at 1320 nm with a gain coefficient of around 0.5 dB/m. Furthermore, we constructed different local structures through simulation and found that compared with the BDF, BPDF has a stronger excited state and a greater significance in O-band. This is mainly because phosphorus (P) doping changes the associated electron distribution and forms the bismuth-phosphorus active center. The fiber has a high gain coefficient, which is of great significance for the industrialization of O-band fiber amplifier.

Improved Radiation Resistance of Er-Yb Co-Doped Silica Fiber by Pretreating Fibers

In this study, a pretreatment method for improving the radiation resistance of Er-Yb co-doped silica fiber (EYDF) is proposed. EYDF is the object in this method and is processed by two steps, including deuterium loading and pre-irradiation. The effects of pretreatment conditions on the laser performance and radiation resistance of EYDF were systematically studied. An online irradiation experiment setup was utilized to evaluate the radiation resistance of EYDF. The results demonstrate that the pretreatment can significantly improve the radiation resistance of EYDF, with minimal impact on the laser output power and slope efficiency. Specifically, the radiation-induced gain variations in the pristine fiber and the pretreated fiber with a cumulative dose of 240 krad were 3.13 dB and 1.81 dB, respectively. Additionally, the high-vacuum experiments show that the proposed pretreatment method can maintain a long-term stable radiation resistance improvement in the fiber. This study provides a method to improve the radiation resistance of EYDF for space applications.

An Innovative Fluorescent Fiber Sensor Based on Ce/Tb Co-Doped Silica Fiber for Partial Discharge Detection

A novel fluorescent fiber sensor based on cerium (Ce) and terbium (Tb) co-doped silica fiber (CTDSF) for partial discharge (PD) detection is proposed. The luminescence mechanism and PD detection principle of CTDSF are theoretically investigated. The CTDSF is fabricated using the rod-in-tube technique combined with the CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser-heated drawing method. The intense emission peak of Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions located at 542 nm ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> - <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> transition) is excited at 302 nm, which indicates the energy transfer between Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> and Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions. Moreover, the excitation peak region near 302 nm is well aligned with the PD light emission spectrum. Subsequently, the PD time domain signals of the needle-plate defect are experimentally measured by utilizing the CTDSF sensor, high-frequency current transformer, and plastic scintillation fiber (PSF). And the experimental results demonstrate that the CTDSF sensor can detect PD signals and has an excellent PD detection linear response with a sensitivity of 0.22 ns∙V/pC. Furthermore, the sensitivity of the CTDSF sensor is approximately 2.4 times dramatically higher than that of the PSF sensor. The CTDSF sensor integrated with the all-fiber system is predicted to have a wide range of potential applications for online PD detection.

Co-Doping Effect of Bismuth Ions on the Gain Characteristics of Er-Doped Silica Optical Fiber

By examining the spectral and amplification characteristics of Er-doped silica fiber (EDSF) and Bi/Er co-doped silica fiber (BEDSF), an active doped silica fiber with broadband- and flat-gain is investigated. Results show that the bandwidth of BEDSF with a gain greater than 20 dB is approximately 50 nm. Moreover, in the entire C-band, the gain of BEDSF exceeds 26 dB with a fluctuation range of approximately 2 dB. The excellent performance may mainly come from the role of bismuth ions. Further analysis demonstrates that the emission and gain cross-sections are enhanced, the bandwidth is broadened, and the flatness is also optimized by co-doping Bi ions. The fluorescence lifetime of Er3+ is lengthened by 1.82 ms, illustrating that there may exist energy transfer from Bi-related active centers to Er3+. The results indicate that the proposed BEDSF has significant potential application in optical fiber amplifiers, lasers, sensors, and so on.

Influence of GeO2 Content on the Spectral and Radiation-Resistant Properties of Yb/Al/Ge Co-Doped Silica Fiber Core Glasses.

In this study, Yb/Al/Ge co-doped silica fiber core glasses with different GeO2 contents (0–6.03 mol%) were prepared using the sol–gel method combined with high-temperature sintering. The absorption, fluorescence, radiation-induced absorption, continuous-wave electron paramagnetic resonance spectra, and fluorescence decay curves were recorded and analyzed systematically before and after X-ray irradiation. The effects of GeO2 content on the valence variations of Yb3+/Yb2+ ions, spectral properties of Yb3+ ions, and radiation resistance of Yb/Al/Ge co-doped silica glasses were systematically studied. The results show that even if the GeO2 content of the sample is relatively low (0.62 mol%), it can inhibit the generation of Yb2+ ions with slight improvement in the spectral properties of Yb3+ ions in the pristine samples and effectively improve its radiation resistance. Direct evidence confirms that the generation of trapped-electron centers (Yb2+/Si-E’/Al-E’) and trapped-hole centers (Al-OHC) was effectively inhibited by Ge co-doping. This study provides a theoretical reference for the development of high-performance, radiation-r esistant Yb-doped silica fibers.

Over 100 mW Stable Low-Noise Single-Frequency Ring-Cavity Fiber Laser Based on a Saturable Absorber of Bi/Er/Yb Co-Doped Silica Fiber

Two kinds of Yb-doped fibers were fabricated, namely, Yb: YAG crystal-derived silica fibers (YCDSFs) with a gain coefficient of 6.0 dB&#x002F;cm, and Bi&#x002F;Er&#x002F;Yb co-doped silica fibers having a Yb concentration of 0.13 <inline-formula><tex-math notation="LaTeX">$ \times $</tex-math></inline-formula> 10²⁶ ions&#x002F;m³. Based on these fibers, a ring-cavity single-frequency fiber laser (SFFL) has been constructed, in which the YCDSF was used as a gain medium and the Bi&#x002F;Er&#x002F;Yb co-doped fiber acted as a saturable absorber. It has been demonstrated that the SFFL had an over 100 mW output at 1030 nm, a slope-efficiency of up to 18.3&#x0025;, and an optical signal-to-noise ratio of over 63 dB. The fluctuation of the output power of the laser was less than 0.65&#x0025; of 103.5 mW within 10 hrs and no mode-hopping was observed for 5 hrs. The SFFL had a linewidth &lt;7.5 kHz at the maximum output power, and the measured relative intensity noise was lower than &#x2212;142 dB&#x002F;Hz at the frequency above 1.0 MHz. The results indicate that the ring-cavity SFFL built could be used as a laser source for applications in high-power fiber laser and high-precision optical fiber sensing and detection.

Temperature Dependence of Absorption and Energy Transfer Efficiency of Er3+/Yb3+/P5+ Co-Doped Silica Fiber Core Glasses.

A high phosphorus Er3+/Yb3+ co-doped silica (EYPS) fiber core glass was prepared using the sol-gel method combined with high-temperature sintering. The absorption spectra, emission spectra, and fluorescence decay curves were measured and compared in temperatures ranging from 300 to 480 K. Compared to 915 and 97x nm, the absorption cross-section at ~940 nm (~0.173 pm2) demonstrates a weaker temperature dependence. Hence, the 940 nm pump mechanism is favorable for achieving a high-power laser output at 1.5 μm. Additionally, the double-exponential fluorescence decay of Yb3+ ions and the emission intensity ratio of I1018nm/I1534nm were measured to evaluate the energy transfer efficiency from Yb3+ ions to Er3+ ions. Through the external heating and active quantum defect heating methods, the emission intensity ratios of I1018nm/I1534nm increase by 30.6% and 709.1%, respectively, from ~300 to ~480 K. The results indicate that the temperature rises significantly reduce the efficiency of the energy transfer from the Yb3+ to the Er3+ ions.

High signal-to-noise ratio fiber laser at 1596 nm based on a Bi/Er/La co-doped silica fiber

We fabricate a high-performance Bi/Er/La co-doped silica fiber with a fluorescence intensity of -33.8 dBm and a gain coefficient of 1.9 dB/m. With the utilization of the fiber as a gain medium, a linear-cavity fiber laser has been constructed, which exhibits a signal-to-noise ratio of 74.9 dB at 1596 nm. It has been demonstrated that the fiber laser has a maximum output power of 107.4 mW, a slope efficiency of up to 17.0%, and a linewidth of less than 0.02 nm. Moreover, an all-fiber single-stage optical amplifier is built up for laser amplification, by which the amplified laser power is up to 410.0 mW with pump efficiency of 33.8%. The results indicate that the laser is capable of high signal-to-noise ratio and narrow linewidth, with potential applications for optical fiber sensing, biomedicine, precision measurement, and the pump source of the mid-infrared fiber lasers.

High gain E-band amplification based on the low loss Bi/P co-doped silica fiber

High gain E-band amplification based on the low loss Bi/P co-doped silica fiber

Amplification in E Band Based on Highly Phosphorus and Bismuth Co-doped Silica Fiber

Amplification in E Band Based on Highly Phosphorus and Bismuth Co-doped Silica Fiber

High-power and highly-efficient laser operation of Tm3+:Ho3+-codoped silica fiber lasers emitting at 2.1 μm and 2.2 μm

High-power and highly-efficient laser operation of Tm³⁺:Ho³⁺-codoped silica fiber lasers emitting at 2.1 μm and 2.2 μm

Electronic and optical properties of Yb/Al/P co-doped silica optical fiber

The corresponding relationship between energy levels and absorption spectra of Yb3+ ion in Yb/Al/P co-doped silica fiber is obtained by first-principle methods. Based on the calculation result that the ortho-position (OP) substitution model has the lowest average formation energy, Yb-OP substitution model with six coordination of Yb3+ is constructed, which is a possible local microstructure in Yb/Al/P co-doped silica fiber. Due to the spin-orbital coupling effect, two occupied impurity levels are introduced into the band gap located at 2.72 eV and 4.06 eV, representing 2F5/2 and 2F7/2 manifolds respectively. The absorption peaks of 971 nm, 922 nm and 881 nm are fitted by Gaussian decomposition, corresponding to the transition 2F7/2-1 - 2F5/2-5, 2F7/2-1 - 2F5/2-6 and 2F7/2-1 -2F5/2-7. We construct the local environment model of Yb3+ ion and provide the relationship between energy levels and optical absorption of Yb3+ ion from the perspective of theoretical calculation, which is helpful to understand the Yb/Al/P co-doped silica fiber theoretically.