Co-doped Phosphate Glass Research Articles

Energy transfer from Ce 3+ to Tb 3+ and Eu 3+ in zinc phosphate glasses

Ce 3+, Eu 3+ and Tb 3+ singly doped and Ce 3+/Eu 3+ and Ce 3+/Tb 3+ co-doped zinc phosphate glasses were prepared by sintering P 2O 5, ZnO, Ce 2(C 2O 4) 3·10H 2O and Eu 2O 3/Tb 4O 7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h. The obtained glasses were homogeneous and transparent. The glasses without Ce 3+ were colorless and those with Ce 3+ showed slightly yellow. The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions. Strong energy transfer from Ce 3+ to Tb 3+ was observed for Ce 3+/Tb 3+ coped samples. There were also some very weak evidences for the energy transfer from Ce 3+ to Eu 3+.

Determination of energy transfer and upconversion constants for Yb3+/Er3+ codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb3+/Er3+ codoped phosphate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3+ to Er3+ as well as the cooperation upconversion coecient Cup from 4I13/2 of Er3+. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same doping concentrations. The determination of these parameters is helpful for the development of Yb3+/Er3+codoped laser glass.

The luminescence properties of Er 3+-doped and Er 3+–Tm 3+-co-doped phosphate glasses for white light emitting diode

Phosphate glasses and glass ceramics doped with Er 3+ and co-doped with Er 3+–Tm 3+ are presented in this work. The luminescence properties have been characterized by absorption, excitation and emission spectra. All samples excited by blue light could emit a combination of blue/green/orange/red wavelength giving white light. For Er 3+-doped glasses, a self-quenching effect has been obtained and an adjustable tune comes out after crystallization. For co-doped glasses, the red emission at 651 nm has been enhanced due to the existence of Tm 3+, which could be relative to both the overlapped emissions and the energy transfer from Tm 3+ to Er 3+.

Study on relaxation oscillation of Er3+/Yb3+ co-doped phosphate glass optical waveguide laser

Based on the principle and fabrication of the optical waveguide laser, and through the configuration of the energy level of Er3+/Yb3+ co-doped system, the time-dependent rate equations are formed and then solved by Runge-Kutta algorithm. The dynamic characteristic of the waveguide laser pumped unidirectionally by 980 nm LD is analyzed. The curves of the relaxation oscillation are drawn, showing that the photon number and inverted population vary alternately. The attenuation characteristic of the peak power is studied. It is gained that time constant changes with pump power, length of waveguide and the reflectivity of output mirror. Furthermore, the impact of the above three parameters on the frequency and end-time of relaxation oscillation is discussed. The frequency of relaxation oscillation is proportional to the pump power. Under high reflectivity conditions, the length of waveguide has a weak impact on the frequency. The end-time decreases as the three parameters increase. These features and results provide a theoretical basis for designing the Er3+/Yb3+ co-doped phosphate optical waveguide laser.

An Erbium -Ytterbium DFB laser with a simple and compact structure

A distributed feedback fiber (DFB) laser operating at 1540 nm having more than 45 dB signal to amplified spontaneous emission ratio with a simple and compact structure is introduced. The DFB laser consists of 45 mm long highly Er-Yb co-doped phosphate glass fiber with a grating structure inside the gain medium. The laser emission is stable, but the power is still relatively lower due to un-optimized grating structure.

Design and Simulation of Broadband IR integrated Waveguide Amplifiers with Long - Period Waveguide Grating Filter

A novel broadband IR integrated Er-Yb codoped phosphate glass waveguide amplifier with a long-period waveguide grating is proposed. The long-period waveguide grating, which is used as a gain equalizer, is directly fabricated in the waveguide. The amplifier model is based on propagation and population-rate equations and includes both uniform and pair-induced up-conversion mechanisms. It is solved numerically by combining overlapping integral and Runge-Kutta(RK) algorithm. The intrinsical gain spectrum of the proposed amplifier is obtained by solving a set of rate and power propagation equations and, the deleterious gain peaking is reduced by the long-period waveguide grating filter. The effects of transmission spectrum of the proposed long-period grating on flattening gain are discussed. An average gain ~ 20dB between 1532 nm and 1565 nm with gain difference of < 3dB is achieved.

Temperature dependence of luminescence behavior in Er 3+/Yb 3+ co-doped transparent phosphate glass ceramics

The effect of temperature on the luminescence intensity of up-conversion and near infrared in Er 3+/Yb 3+ co-doped phosphate glass ceramics has been investigated. Efficient green and red up-conversion luminescence and strong infrared fluorescence at 1.54 μm wavelength are observed under excitation of 975 nm. The fluorescence intensity is changing at different temperature and the results are explained with the level transitions in Er 3+/Yb 3+ co-doped system. Meanwhile, the lifetime of Er 3+: 4I 13/2 level corresponding to different operating temperature and pump power is also discussed, and the experimental results are fitted using multiphonon relaxation theory.

High SBS-threshold single-mode single-frequency monolithic pulsed fiber laser in the C-band

We report a high SBS-threshold, single-frequency, single-mode, polarization maintaining (PM) monolithic pulsed fiber laser source in master oscillator and power amplifier (MOPA) configuration that can operate over the C-band. In order to achieve a narrow transform-limited linewidth for pulses longer than 100 ns, we use a single-frequency Q-switched fiber laser seed, which itself can be seamlessly tuned up to 1.24 micros. The Q-switched pulses are amplified in the power amplifier stage of MOPA using a high SBS threshold single-mode PM large core highly Er/Yb co-doped phosphate glass fiber (LC-EYPhF). This seed and amplifier combination represents the first monolithic, all-fiber implementation of a single-frequency pulsed laser with the highest pulse energy of 54 microJ and peak power of 332 W for 153-ns pulses at 1538 nm.

Efficient Fibre Amplifiers Based on a Highly Er3+/Yb3+ Codoped Phosphate Glass-Fibre

Highly Er3+/Yb3+-codoped single-mode phosphate glass fibre is fabricated by the rod-in-tube technique. The performances of high-concentration Er3+/Yb3+-codoped phosphate glass fibre amplifiers are investigated and discussed. An efficient optical fibre amplifier with a gain of 12.6 dB based on a 3.0 cm long Er3+/Yb3+-codoped phosphate glass fibre is demonstrated under a dual-pump configuration with two 976 nm fibre-pigtail laser diodes, which make it attractive for compact Er3+ -doped fibre amplifiers. The obtained noise figures of signal wavelength from 1525 to 1565 nm are less than 6.0 dB. Gain saturation behaviour at 1535 nm is also investigated, and the obtained saturation output power is larger than 10 dBm.

Effects of Ce3+ on the spectroscopic properties of transparent phosphate glass ceramics co-doped with Er3+/Yb3+

We have prepared Er3+/Yb3+ co-doped transparent phosphate glass ceramics by the high-temperature melting technique, and demonstrated the influence of energy acceptors Ce3+ ions on the up-conversion and 1.54μm emission properties of Er3+. The energy transfer mechanism is discussed based on the energy matching and the energy level structure. The phonon-assisted energy transfer between Er3+ and Ce3+ favors population feeding from the 4I11/2 to the 4I13/2 level, and therefore drastically decreases the up-conversion emission intensity of Er3+. Meanwhile, 1.54μm fluorescence enhances greatly with the introduction of Ce3+ ions at the proper concentration.

Energy transfer and enhanced broadband near-infrared luminescence in Yb–Bi codoped phosphate glasses

In this article, we report on enhanced broadband near-infrared emission in Yb–Bi codoped phosphate glasses. The emission intensity of Yb–Bi codoped glass was ˜32 times larger than that of Bi-doped glass when excited with 980-nm laser diode. The highest 1/e fluorescent lifetime of Yb–Bi codoped glass reached 1650 μs. The dependence of emission intensity and fluorescent lifetime on Yb2O3 concentration was investigated. The enhancement of the near-infrared emission is due to energy transfer from Yb3+ (2F5/2–2F7/2) transition to Bi ions, and the highest energy transfer efficiency reached 50%. Yb–Bi codoped phosphate glass should be a promising candidate for broadband optical amplification.

Laser Characteristics of Cladding-Pumped Short Er3+/Yb3+ Codoped Single Mode Phosphate Glass Fibre

We experimentally investigate the laser characteristics of a series of short pieces of newly-developed Er3+/Yb3+ codoped single mode phosphate glass fibres via the cladding pump of a 976nm multimode laser diode. A stable continuous-wave single transverse mode laser with over 85mW at 1553 nm is generated from a 5.5-cm-long active fibre. Single mode laser output power per unit length is up to 15mW/cm. Moreover, the slope efciency is 11.8% when the pump power is below 940mW and the 3dB linewidth is 0.06nm at the maximum pump power. The numerical simulation results show that the laser emission slope efficiency can exceed 20% by means of increasing the coupling efficiency of the pump to the fibre core further.

Self-Starting Passively Mode-Locked Er3+/Yb3+ Codoped Phosphate Glass All-Fibre Ring Laser

A self-starting, passively mode-locked all-fibre ring laser based on the homemade Er3+/Yb3+codoped phosphate glass fibre is reported. Dual-pump sources were used to achieve the mode-locked operation in the experiment. The fundamental mode-locked pulse repetition rate is 10.67 MHz. The pulse duration, assumed as the fit of hyperbolic secant pulse shape, is 5.82ps. We also observe the multi-pulse output of the fibre laser.

Comparison of optical parameters and luminescence between Er3+/Yb3+ codoped phosphate glass ceramics and precursor glasses

Er 3 + / Yb 3 + codoped transparent phosphate precursor glasses and glass ceramics have been fabricated and characterized. The formation of ErPO4 and YbPO4 nanocrystals was studied using x-ray diffraction. The intensity parameters, the spontaneous radiative transition probabilities, the branching ratios, and the radiative lifetimes of Er3+ in both glass ceramics and precursor glasses were calculated based on the Judd–Ofelt theory, and the crystallization process in the glass ceramics is confirmed by the optical parameters obtained. Under 975 nm wavelength excitation intense 1.54 μm fluorescence and upconversion luminescence were observed in the glass ceramics, the quantum efficiency of the Er3+ I413/2→I415/2 transition is 95%, and the transition mechanisms of the upconversion luminescence are due to a two-photon process.

Numerical investigation of gain characteristics of Er3+/Yb3+ co-doped fiber amplifiers

Inthiswork,amodelforanalyzingthegaincharacteristicsofheavilyEr 3+ /Yb 3+ co-doped compactfiber amplifier is presented. Four-level rate equations andfinite-difference beam propagation method are applied to simulate the optical field evolution along the active fiber. Based on this model, the influences of ion concentration, fiber length and pump power on the gain characteristics of Er 3+ /Yb 3+ co-doped phosphate glass fiber amplifiers are the- oretically investigated. Numerical results show that for a fiber length of 3.6cm the internal gain can reach 27.2dB with NEr = 2.6 × 10 26 ions/m 3 and NYb = 1.2 × 10 27 ions/m 3 when pumped with 224mW at 980nm. The gain per centimeter is 7.56dB/cm. The results can provide useful information to optimize the gain performance of these compact fiber

Compact high power broadband Er3+−Yb3+-codoped superfluorescent fiber source

Compact high power broadband superfluorescent fiber source has been demonstrated using an ultrashort Er3+−Yb3+-codoped phosphate glass fiber. The fiber is 10.4-cm-long and at 1.68 W pump power, an output power of 16.85 mW, a mean wavelength of 1540.9 nm, a bandwidth of 18.4 nm, and a slope efficiency of 18.6% have been obtained. The dependence of output power, mean wavelength, and bandwidth stability on pump power and fiber length are also studied, and there is an excellent agreement between the theoretical results and experimental data.

Comparative studies of spectroscopic properties in Er3+–Yb3+ codoped phosphate glasses

Abstract A spectroscopic investigation of an extensive series of commercially available Er 3+ –Yb 3+ codoped phosphate glasses (IOG-1) with different Er–Yb concentrations have been presented based upon spectroscopic measurements and Judd–Ofelt theory. The composition and the atomic concentration of the respective elements of the glass samples were analyzed. Various spectroscopic parameters were obtained to evaluate the performances of these glasses as a laser material in the eye-safe laser wavelength of 1.53 μm. Using the measured fluorescence lifetimes the radiative quantum efficiency of the 4 I 13/2 → 4 I 15/2 transition is estimated to be ∼100% for the glass substrates with an Er 3+ concentration of lower than 2.0 × 10 20 ions/cm 3 . The stimulated emission and absorption cross-sections were also determined and compared. The infrared and upconversion fluorescence were studied, and under 975 nm excitation the dominant upconversion mechanisms are excited state absorption (ESA) and energy transfer (ET) for the green emission, and ET for the red emission. The data obtained here provide useful guidelines on the choice of IOG-1 glasses with the fixed Er–Yb concentrations.

Waveguide formation by ion implantation in Er doped optical materials

High energy medium-light ion implantation was applied on both z-cut Er:LiNbO3 and Er3+–Yb3+ co-doped phosphate glasses, in order to fabricate optical waveguides on optically amplifying media.Preliminary results obtained with Er:LiNbO3, implanted with 3.9MeV Carbon ions, have demonstrated the possibility to fabricate good quality waveguides, the optical characteristics of which depend on implantation fluence and post-annealing process. Er3+–Yb3+ co-doped phosphate glass substrates were implanted with both 2.8MeV Carbon ions, at fluences ranging from 3×1014ions/cm2 to 1×1015ions/cm2, and with 3.4MeV Oxygen ions at a fluence of 1×1015ions/cm2. Also in this case, planar optical waveguides were formed, but, under the as-reported implantation conditions, the possibility to tailor the refractive index profiles was very reduced. In this work, the optical properties of the integrated optical waveguides obtained on different doped substrates are examined.

Distributed feedback fiber laser pumped by multimode laser diodes

A distributed feedback fiber laser made of highly Er-Yb codoped phosphate glass fiber has been demonstrated experimentally. Efficient pump absorption allows for multimode pumping into the cladding of the active fiber. Output powers up to 160 mW have been achieved. The 35 mm long fiber laser device emits with >50 dB side mode suppression ratio.

Enhanced broadband near-infrared luminescence and optical amplification in Yb–Bi codoped phosphate glasses

Yb–Bi codoped phosphate glass was prepared and its properties were compared with Bi-doped phosphate glass. The broadband infrared luminescence intensity from Yb–Bi codoped glass was ∼32 times stronger than that of Bi-doped glass. The single-pass optical amplification was measured on a traditional two-wave mixing configuration. No optical amplification was observed in Bi-doped glass, while apparent broadband optical amplification between 1272 and 1336nm was observed from Yb–Bi codoped glass with 980nm laser diode excitation. The highest gain coefficient at 1272nm of Yb–Bi codoped glass reached to 2.62cm−1. Yb–Bi codoped phosphate glass is a promising material for broadband optical amplification.