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In this work, we have used the thermal lens technique combined with conventional spectroscopy to characterize the thermo-optical properties of Er3+-doped lead pyrophosphate-based glasses. More precisely, we have investigated and quantified experimentally the fluorescence quantum efficiencies of the Er3+ levels, and we describe the role of concentration quenching effects. The fluorescence quantum efficiency of the 4I13/2 level is very high when compared to other phosphate glasses, while that of the green-coupled levels is very small. Other important photonic materials parameters, such as the thermal diffusivity and temperature coefficient of the optical path length change, were obtained and compared with those of other glass systems. The cumulative results obtained here for the Er-doped lead pyrophosphate glass show that this material is a good candidate for photonic applications with a characteristic Er3+ infrared emission around 1550 nm. [ABSTRACT FROM AUTHOR]

In this paper, a stable and robust all-fibre passively Q-switched erbium-doped fibre laser (EDFL) emitting at 1558 nm is described. The proposed laser utilizes an 11 cm long erbium-doped fibre as saturable absorber (SA). The fibre SA features a linear optical absorption of about 13 dB in the Q-switched EDFL operating regime. By elevating the input pump power from the threshold of 60 mW to the maximum available power of 142 mW, a pulse train with a maximum repetition rate of 86 kHz, minimum pulse width of 3.39 µs, maximum average output power of 10.5 mW, maximum pulse energy of 122 nJ and maximum peak power of 36 mW are obtained. The signal to noise ratio (SNR) of the spectrum is measured to be around 70 dB. This fibre SA is simple, reliable, compact and alignment free. Thus it is suitable for making a portable pulse laser source. [ABSTRACT FROM AUTHOR]

Abstract This study was undertaken to investigate the influence of Er addition on microstructure and mechanical properties of as-cast Mg-10Li-5Zn alloy. With addition of Er, the grain size of as-cast alloys is greatly reduced, meanwhile, Mg-Zn-Er phase forms and increases gradually and Mg-Li-Zn phase decreases. The Mg-Zn-Er phase is mainly W-phase. The size of W-phase becomes larger with the increase of Er content from 0.5 wt% till 3.5 wt% and W-phase is mainly distributed from in the grain interiors to along the grain boundaries as well. The size, quantity and distribution of W-phase is an important factor that influences the mechanical properties of Mg-10Li-5Zn- x Er alloys. Overmuch coarse W-phase in the grain boundaries is detrimental to strength. The Mg-10Li-5Zn-0.5Er alloy exhibits an optimum combination of tensile properties with the ultimate tensile strength, yield strength and elongation of 198 MPa, 223 MPa and 14.7%. The optimal Er addition in as-cast Mg-10Li-5Zn alloy is ~0.5 wt%. [ABSTRACT FROM AUTHOR]

In this work, a wavelength-switchable erbium-doped fiber (EDF) glasses-type compound-ring (GTCR) laser with stable single-longitudinal-mode (SLM) oscillation is proposed and presented. In the experiment, to accomplish wavelength-tunable operation, a silicon-micro-ring-resonator (SiMRR) is utilized inside the ring cavity, when the birefringent loss of EDF laser is adjusted properly. Moreover, the GTCR configuration is proposed to as the mode-filter for suppressing the multi-longitudinal-mode (MLM) to achieve the SLM oscillation. Here, the measured linewidth of output wavelength is ∼61 kHz. The output stabilities of the proposed SiMRR EDF compound-ring laser are also discussed experimentally. [ABSTRACT FROM AUTHOR]

Er3+-doped (Bi1−xErx)2O3 (where x = 0.1, 0.13, 0.15, and 0.2) nanoparticles (NPs) with a single fluorite-type structure have been synthesized by the sol-gel method and sintered at 850°C for 3 h. Here E2O3-stabilized δ-Bi2O3 has been obtained at low erbium concentrations. Rietveld refinement confirms an Ln-O bond length increase by a crystallographic volume variation from 166.51(1) to 168.54(1) Å3, as a consequence of enhanced ionic conductivity, which proved to be inversely proportional to the increase in Er3+ concentration. A reduction in the small cation (Er3+) concentration (x = 0.1) induces a grain boundary resistance decrease in the intermediate temperature (IT) range. A marked compressive stress tensor at high temperature was also observed, even at lower Er3+ cation concentrations, where the tetragonal structure takes place. The β-(Bi1−xErx)2O3 solid-state oxide ion conductor proved to have potential as a solid oxide electrolyte at ITs due to its conductivity and high compressive residuals stress (− 370 MPa). [ABSTRACT FROM AUTHOR]

Absorption, excitation, fluorescence and decay spectra are carried out at room temperature on Er 3+ (1%), Yb 3+ (4%): Cd .7 Sr .3 F 2 mixed single crystals. These crystals, with a good optical quality, are grown by the standard Bridgman method. This work concerns mainly the spectroscopic properties of the Er 3+ ions incorporated in a fluorite-type crystal. Using the room temperature absorption spectra, the standard Judd–Ofelt (JO) model is applied to absorption intensities of Er 3+ to obtain the three phenomenological intensity parameters by the least square fit procedure. The values obtained are in accordance with those of other fluoride hosts with good root mean square fitting. Compared to oxide materials, fluoride materials have, in general, low values ​​of Ω 2 . The low value of Ω 2 is correlated to the cubic nature of the site occupied by the rare earth in the host matrix. These JO intensity parameters are then applied to determine the radiative transition probabilities (A JJ′ ), radiative lifetimes (τ rad ) and branching ratios (β JJ′ ) of Er 3+ transitions. The green emission generated by the Er 3+ ions directly excited in UV level, consisting in three well-resolved major lines, is more intense than the one. We have measured the fluorescence lifetime, the cross-section emission, the gain and the radiative quantum efficiency for both green and red band emissions. The obtained results are in good agreement with those of other fluoride laser crystals. From, the obtained spectroscopic data we suggest that Cd .7 Sr .3 F 2 may offer green and red visible laser emission when doped with Er 3+ ions. [ABSTRACT FROM AUTHOR]

We report on an environmentally stable, all-PM-fibre, Er-doped, mode-locked laser with a central wavelength of 1550 nm. Significantly, the laser possesses large net-normal dispersion such that its dynamics are comparable to that of an all-normal dispersion fibre laser at 1 μ m with an analogous architecture. The laser is mode-locked with a nonlinear amplifying loop mirror to produce pulses that are externally compressible to 500 fs. Experimental results are in good agreement with numerical simulations. [ABSTRACT FROM AUTHOR]

The evolution of Ytterbium 2 F 5/2 and Erbium 4 I 13/2 energy level lifetimes versus doses of various radiation types (40 keV X-rays, 480 MeV protons, 1.2 MeV γ-rays and 6 MeV electrons) were investigated on samples of silica-based Rare-Earth Doped optical Fibers (REDFs). For each studied sample (Er-doped and Er/Yb-doped), a strong dependence of the lifetime value on the irradiation dose (for equivalent doses ranging from 10 Gy(SiO 2 ) to 10 MGy(SiO 2 )) is observed regardless of the radiation nature. For both fiber types and luminescent ions, complex dose dependences are observed: a limited decrease of the lifetime at the lower doses, whereas a large reduction is reported at doses exceeding 100 kGy(SiO 2 ). The results highlighted the vulnerability of REDF based systems, such as optical amplifiers and sources, for space and nuclear applications. In such harsh environments, Radiation Induced Attenuation (RIA) is also a key issue. The positive effect of Ce co-doping on both the RIA and the lifetimes is reported even at the highest dose of 10 MGy(SiO 2 ). The basic mechanisms involved during the interaction between radiation and fiber material were also investigated through low temperature spectroscopic measurements that revealed the fundamental role of radiation-induced point defects. [ABSTRACT FROM AUTHOR]

Phosphate glasses with various Er 2 O 3 content have been prepared by the melt-quenching method. Differential thermal analysis was also carried out to obtain the glass transition and the crystallization temperatures, related to the thermal stability of the sample. Optical parameters such as refractive index n, complex dielectric constant (ɛ* = ɛ 1 + iɛ 2 ), and complex optical conductivity (σ* = σ 1 + iσ 2 ) of these glasses were determined by spectroscopic ellipsometry in the spectral range 1.5–4.5 eV at incident angle 78°. The glass samples present a low refractive index ( n ( λ ) does not exceed 1.46) compared to other glasses. The real ε 1 and imaginary parts ε 2 of the dielectric constant ε, show that in 3.7–4.4 eV energy range, there is no dispersion and the absorption is minimal therefore, in this small domain our samples are good candidates to be exploited in the propagation of the electromagnetic waves. [ABSTRACT FROM AUTHOR]

An Er 3+ /Yb 3+ co-doped bismuthate (Bi 2 O 3 -B 2 O 3 -CaO) glass was prepared by melt quenching method. The samples were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), absorption and emission spectroscopy. The Judd-Ofelt parameters (Ω λ ) were determined from the intensity of the absorption band to calculate the radiation parameters, such as the radiation lifetime (τ rad ), radiation transition probability (A rad ) and branching ratio (β JJ′ ) of 4 I 13/2 laser conversion of Er 3+ ions. The effective emission bandwidth (Δλ P ), stimulated emission cross section (σ se ) and gain bandwidth (σ se × Δλ p ) were determined on the emission spectra, and the optimum doping concentration of Er 2 O 3 was 0.5 mol%. The present work indicates that Er 3+ /Yb 3+ co-doped bismuth calcium borate glass can be promising materials for solid state NIR lasers and fiber amplifiers. [ABSTRACT FROM AUTHOR]

A passively Q-switched microsecond Er-doped fiber laser at 1532 nm wavelength was demonstrated by using a ReS-based saturable absorber. The absorber was fabricated with ReS by exfoliating mechanically and transferred onto a fiber end. Stable Q-switched laser pulses were observed with the shortest pulse duration of 2.1 μs, the maximum average output power of 2.48 mW, and the pulse with energy up to 38 nJ. Our experimental results suggest that ReS is potential for a Q-switcher near 1.55 μm wavelength. [ABSTRACT FROM AUTHOR]

Compact and sensitive Er 3+ /Yb 3+ co-doped YAG single crystal optical fiber thermometry based on up-conversion (UC) luminescence is presented. The thermal probe is a YAG single crystal fiber with end Er 3+ /Yb 3+ co-doped grown by laser heated pedestal growth method. Excited by a 976 nm laser diode, the UC fluorescence intensity ratio (FIR) of the Er 3+ ions in two emission bands ( 2 H 11/2 , 4 S 3/2 → 4 I 15/2 ) was investigated in the temperature range from 298 K to 723 K. The results indicate that the maximum temperature sensitivity is approximately 0.00486 K −1 at 577 K. Thus, the Er 3+ /Yb 3+ co-doped YAG single crystal fiber has potential application in optical thermometry by the FIR technique. Furthermore, the thermal probe has compact structure and high thermal stability, making it a more convenient and effective optical fiber temperature sensor. [ABSTRACT FROM AUTHOR]

Up-conversion luminescence spectra of Er 3+ ions in multicomponent oxyfluoride glasses GeO 2 – BaO – BaF 2 – Ga 2 O 3 – Er 2 O 3 were examined. It was found that the up-conversion luminescence spectra of Er 3+ are dependent on pumping wavelengths. The spectra recorded upon the excitation at 800 nm contained an intense green up-conversion luminescence corresponding to the 2 H 11/2, 4 S 3/2 → 4 I 15/2 transitions and a very weak red luminescence related to the 4 F 9/2 - 4 I 15/2 transition. In spectra recorded upon 980 nm excitation the contribution of the red luminescence was markedly higher. The interaction mechanisms involved in up-conversion processes are proposed and observed dependence of intensity of up-converted luminescence on excitation power is discussed. The experimental results suggest that Er 3+ singly doped lead-free oxyfluoride germanate glass is useful for up-conversion luminescence applications. [ABSTRACT FROM AUTHOR]

The single-, dual- and triple-wavelength passively mode-locked erbium-doped fiber lasers are demonstrated with MoS2 and polarization-dependent isolator (PD-ISO). The saturable absorber is fabricated by wrapping an MoS2 around a microfiber. The intracavity PD-ISO acts as a wavelength-tunable filter with a polarization controller (PC) by adjusting the linear birefringence. Single-wavelength mode-locked fiber laser can self-start with suitable pump power. With appropriate PC state, dual- and triple-wavelength operations can be observed when gains at different wavelengths reach a balance. It is noteworthy that dual-wavelength pulses exhibiting peak and dip sidebands, respectively, are demonstrated in the experiment. The proposed simple and multi-wavelength all-fiber conventional soliton lasers could possess potential applications in numerous fields, such as sensors, THz generations and optical communications. [ABSTRACT FROM AUTHOR]

Trivalent erbium (Er 3+ ) and erbium-yttribium (Er 3+ /Yb 3+ ) co-doped Y 2 CaZnO 5 (YCZ) nanophosphors were synthesized via Sol-Gel combustion method and applied as photon up-converter in dye sensitized solar cell (DSSC) and studied for their photovoltaic properties. A bright green and green–red up-conversion emission is observed upon an excitation of 980 nm in Er 3+ :YCZ and Er 3+ /Yb 3+ :YCZ nanophosphors, respectively which indicates the possibility of using these phosphors for light harvesting applications. The prepared Er 3+ and Er 3+ /Yb 3+ co-doped YCZ nanophosphors were incorporated in TiO 2 based DSSC to form the composite photoelectrode and studied the power conversion efficiency (PEC). With the incorporation of Er 3+ and Er 3+ /Yb 3+ co-doped YCZ nanophosphors in the DSSC resulted in the enhanced PCE of 6.01% and 7.21% using durable methoxypropionitrile (MPN) and volatile acetonitrile (AcN) based electrolytes, respectively. The PCE values obtained for the studied compounds are found to be either comparable or better than the other reported compounds used for the light harvesting. An enhanced photocurrent (J SC ) of 12.44 and 13.28 mA/cm 2 , for Er 3+ :YCZ and Er 3+ /Yb 3+ :YCZ nanophosphors based DSSC, respectively was observed under AM1.5 G light due to the better photon conversion efficiency of the nanophosphor. The detailed up-conversion (UC) mechanism responsible for the enhanced PCE properties were discussed in detail and the results were compared with similar phosphor systems. [ABSTRACT FROM AUTHOR]

Series of Er 3+ -activated La 2 MoO 6 nanoparticles were prepared by a traditional sol-gel method. Under the excitation of 379 nm, the resultant compounds revealed dazzling emissions that can be seen by naked eye. With the increment of Er 3+ ion concentration, the emission intensity showed an upward tendency and reached its maximum value when the doping concentration was 2 mol%. The critical distance was calculated to be 23.41 Å and the dipole-dipole took the domination in the concentration quenching mechanism. Furthermore, by means of a fluorescence intensity ratio technique, the temperature sensing performances of the synthesized samples in the temperature range of 303–463 K were investigated based on the thermally coupled levels, 2 H 11/2 and 4 S 3/2 , of Er 3+ ions. It is found that the sensor sensitivity of Er 3+ -activated La 2 MoO 6 nanoparticles can be greatly affected by the doping concentration and the maximum sensor sensitivity was determined to be about 0.0097 K −1 at 463 K. In addition, the prepared nanoparticles also exhibited splendid water resistance behaviors. These results demonstrate that the Er 3+ -activated La 2 MoO 6 nanoparticles are promising candidates for simultaneous solid-state lighting and non-contact thermometry. [ABSTRACT FROM AUTHOR]

A method of core-shell-like gradient permeation of Er on the surface of grain was used to prepare xEr-BiNaTiO ceramics. The structure and photoluminescence properties were investigated both on the gradient and homogenous doping. The XRD patterns exhibited a single rhombohedra phase. The photoluminescence measurements showed a maximum value at x = 1.5 wt% for the gradient xEr-BiNaTiO ceramics, and a maximum value at x = 2.0 wt% for the homogenous one, also critical concentrations of elimination of segregation of large strip grains. Significantly, an enhanced efficiency of bright green emission at about 550 nm was observed in the gradient Er-BiNaTiO ceramics. In structure a critical concentration of elimination of segregation of large strip grains corresponds to the highest PL peak. The possible mechanism was discussed that concentration quenching effect is supposed due to the degeneration effect of multi-rare earth ions to allow energy transfer accompany with non-radiative loss. Gradient concentration will cause gradient overlapping energy levels to restrict energy transfer to enhance luminescence effect. [ABSTRACT FROM AUTHOR]

Crystalline phase evolution through merely adjusting composition was achieved in silicate glass ceramics containing Lu n O n-1 F n+2 (n = 5–10) nanocrystals. Orthorhombic or cubic phase nanocrystals were precipitated in the aluminosilicate glass matrix after thermal treatment together with varying the Na 2 O/NaF ratio. Oxyfluoride nanocrystals with quasi-spherical shape show homogenous and dense distribution in glass matrix by transmission electron microscopy measurement. Intense upconversion and mid-infrared emissions were realized in these glass ceramics compared to the precursor glass, and the emission spectral shapes, relative emission intensity and fluorescence decay curves of Er 3+ in cubic LuOF embedded samples exhibit remarkable differences due to the crystal phase dependent effect in glass ceramics. These results indicate that the crystallization and luminescence properties of oxyfluoride glass ceramics could be modified through the alteration of glass composition, which could be used for the development of novel glass ceramics and design of luminescent properties. [ABSTRACT FROM AUTHOR]

The synthesis and optical characterizations of CaLaGa 3 O 7 crystals with different Er dopant concentration are reported. The optical parameters related to absorption and emission cross-sections were evaluated and compared. It was found that the NIR fluorescence weakens, at the same time Mid-IR fluorescence intensity strengthens with the increment of Er 3+ ion dopant concentration in Er: CaLaGa 3 O 7 crystals. Furthermore, the energy transfer mechanism in Er: CaLaGa 3 O 7 crystal was studied in this work. Besides, the radiative transfer microscopic parameters of 4 I 11/2 and 4 I 13/2 levels were theoretically analyzed. Hence, these results indicate that 30 at% Er 3+ doped CaLaGa 3 O 7 crystal has potential applications in 2.7 μm laser. [ABSTRACT FROM AUTHOR]

The comparative analysis of optical characteristics inherent to Er2O3/SiC and Er2O3/por-SiC/SiC structures has been performed. It has been shown that, regardless the substrate on which the Er2O3 film is formed, an increase in the rapid thermal annealing time leads to an improvement in the oxide film composition, with the composition of the Er2O3 film approaching to the stoichiometric one. At the same time, introduction of an additional porous SiC layer leads to a blurring of the oxide film/substrate interface and broadening the photoluminescence band measured in this structure. [ABSTRACT FROM AUTHOR]

We describe a systematic approach to design, optimize, and characterize a Fourier-domain modelocked (FDML) laser with an erbium-doped fiber amplifier (EDFA) as the optical gain medium. A highly stable temporal intensity profile is obtained by minimizing chromatic dispersion and polarization fluctuations. The obtained bandwidth of 21 nm, tuning speed of 50 kHz, and output power of 5 mW are the highest reported so far with an EDFA-based FDML laser. [ABSTRACT FROM AUTHOR]

Characteristics of noise in erbium doped fiber amplifier (EDFA) are theoretically analyzed and experimentally verified. Four discreet energy models are used for erbium ion transition. Spatially varying photon number for traveling optical field was defined in a spatially divided segment with finite length, whose length is decided by property of the spontaneous emission. Quantitative evaluation of the Langevin noise sources becomes possible by this model. The amplified spontaneous emission was included in terms of discrete longitudinal mode, which is defined for whole length of the EDFA. It was found that the relative intensity noise (RIN) in the EDFA hardly changes with noise frequency in the region higher than several kHz. The phase noise in EDFA also hardly changes with the noise frequency. The frequency noise of the signal light in the EDFA increases proportional to squared value of the noise frequency. The amount of RIN and the phase noise decrease in higher input optical power. Good correspondence between theoretical and experimental results was obtained. [ABSTRACT FROM AUTHOR]

The authors have synthesized Er(III)-doped BiOCl microplates by a solid-state reaction method. Under irradiation with 980 nm light, the microplates emit both green and red upconversion emissions originating from the transitions of Er(III) ions. By properly adjusting the concentration of the Er(III) ions, the colors can be tuned from pure green to yellowish green. The optimal doping concentration is 3 mol%. Furthermore, the ratio of the two green emission bands of the Er(III) ions is strongly temperature-dependent. The doped microplates can be used to sense temperature in the 298 to 778 K range, indicating a maximum sensitivity of 2.8 × 10 K. The sensitivity is independent of Er(III) ion concentration. The internal heating properties of the microplates induced by the laser excitation are also discussed. Theoretical analysis reveals that the temperature of the doped BiOCl microplates increases from 276 to 324 K with elevating the laser power from 246 to 445 mW. [ABSTRACT FROM AUTHOR]

Rare earth doped materials can usually achieve high efficiency upconversion luminescence (UCL) under high power density infrared laser excitation, in which process the heat generation cannot be avoided, and then induce temperature dependent UCL quenching. This paper dealt with the temperature sensing property and 1550 nm laser irradiation induced thermal effect of Er 3+ /Yb 3+ co-doped NaYF 4 microcrystals. The sample was synthesized via a microwave-assisted hydrothermal route, and its crystal structure and microscopic morphology were characterized by means of XRD and FE-SEM. To describe the temperature quenching behaviors for the two typical green emissions of Er 3+ , a model was proposed and well explained the temperature dependence of two green UCL intensities. Temperature sensing property for NaYF 4 : Er 3+ /Yb 3+ microcrystals were studied by fluorescence intensity ratio technique, and the temperature sensitivity were also obtained. Furthermore, the 1550 nm laser induced thermal effect was studied, and the result showed that the sample temperature increased with increasing excitation power density. [ABSTRACT FROM AUTHOR]

The production of Er 3+ -doped willemite glass-ceramic using waste soda lime silica (SLS) glass was reported in this study. The precursor glass and glass-ceramics were prepared using conventional melt-quenching technique with empirical formula (Er 2 O 3 ) x [(ZnO) 0.5 (SLS) 0.5 ] 1-x where x = 1 wt.% and sintered at various temperatures. The trend of density and the linear shrinkage of the glass-ceramic samples were increased with the progression of sintering temperature. The crystallization behaviour and surface morphology of the glass-ceramics was studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). It was revealed that at a lower sintering temperature (700 °C), the stable state of α-willemite (α-Zn 2 SiO 4 ) phase was formed. Fourier transform infrared (FTIR) spectroscopy reveals that the presence of different functional groups in the samples. Three transition states of excitation were shown in UV–visible (UV–vis) spectra which arise from the ground state 4 I 15/2 to the excited states 4 F 7/2 , 2 H 11/2 , 4 F 9/2 . Broad green emission at 557 nm under excitation 385 nm was obtained. These spectra reveal that the luminescence of the samples was increased with the progression of sintering temperature due to the presence of Er 3+ ions into the willemite crystal. Such luminescence of glass and glass-ceramics are expected to have potential applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Na 5 Lu 9 F 32 single crystals co-doped with various Er 3+ /Yb 3+ concentrations were grown by an improved Bridgman method for the first time. The crystal structure is characterized by means of X-ray diffraction (XRD). High transmission in the range from 400 nm to 7150 nm and maximum phonon energy about 441 cm −1 for the Na 5 Lu 9 F 32 single crystals are obtained from the measured transmission and Raman spectra, respectively. The Judd-Ofelt parameters of Er 3+ in the obtained crystal was calculated and discussed according to the measured absorption spectra. Compared with the Er 3+ single-doped Na 5 Lu 9 F 32 crystal, an obviously enhanced emission band at 1500 nm was observed upon excitation of 980 nm laser diode (LD) via energy transfer from Yb 3+ to Er 3+ . Decay curve fitting using a Inokuti-Hirayama expression indicates dipole-dipole energy transfer from Yb 3+ to Er 3+ .The maximum emission cross section at ∼1.5 μm was also calculated to be 10.12 × 10 −20 cm 2 for the Na 5 Lu 9 F 32 single crystal of 1% Er 3+ and 6% Yb 3+ in molar fraction doping concentration. [ABSTRACT FROM AUTHOR]

The pure and Er3+-modified binary Pb(Zn1/3Nb2/3)O3–9PbTiO3 (PZN–9PT) single crystals were grown by using the flux method. The phase structure of the as-grown single crystals at room temperature was confirmed by the x-ray diffraction analysis. The effect of Er3+ addition on the electrical properties and upconversion luminescence of PZN–9PT was investigated. The rhombohedral to tetragonal phase transition temperature and the Curie temperature of the Er3+-modified PZN–9PT single crystals were 370 and 451 K, respectively. The coercive field EC at room temperature was evidently higher by 11.6 kV/cm than that of the PZN–9PT single crystals (EC, ∼3.5 kV/cm). Furthermore, the green and red upconversion emission bands were obtained under the 980 nm excitation, which are related to (2H11/2, 4S3/2) → 4I15/2 and 4F9/2 → 4I15/2 transitions. [ABSTRACT FROM AUTHOR]

We report on the sintering promoting and fluorescent activator roles of Er 3+ in AlON:Er 3+ transparent ceramics prepared by pressureless sintering with Er 2 O 3 and AlON powder. There shows that the transparency of samples varied with the content of Er 2 O 3 additive. The AlON:Er 3+ ceramics showed upconversion luminescence peaking at 546 nm, 662 nm and 840 nm under the 980 nm excitation due to transition of 4 S 3/2 / 2 H 11/2 → 4 I 15/2 , 4 F 9/2 → 4 I 15/2 and 4 S 3/2 / 2 H 11/2 → 4 I 13/2 of Er 3+ ions, respectively. The infrared spectra exhibited strong emission at 1534 nm corresponds to 4 I 13/2 → 4 I 15/2 transition. The mechanism of the IR and visible emission bands in AlON:Er 3+ ceramics are discussed, which suggest it should be attractive for lighting and display devices applications. [ABSTRACT FROM AUTHOR]

Understanding the luminescence of GaN doped with erbium (Er) requires a detailed knowledge of the interaction between the rare-earth dopant and the nitride host, including intrinsic defects and other impurities that may be present in the host material. We address this problem through a first-principles hybrid density functional study of the structure, energetics, and transition levels of the Er impurity and its complexes with N and Ga vacancies, substitutional C and O impurities, and H interstitials in wurtzite GaN. We find that, in the interior of the material, ErGa is the dominant Er3+ center with a formation energy of 1.55 eV, ErGa-VN possesses a deep donor level at 0.61 eV which can assist in the transfer of energy to the 4felectron core. Multiple optically active Er3+ centers are possible in Er-doped GaN. [ABSTRACT FROM AUTHOR]

The electronic structure of a novel lanthanide-based single-ion magnet, {C(NH2)3}5[Er(CO3)4]·11H2O, was comprehensively studied by means of a large number of different spectroscopic techniques, including far-infrared, optical, and magnetic resonance spectroscopies. A thorough analysis, based on crystal field theory, allowed an unambiguous determination of all relevant free ion and crystal field parameters. We show that inclusion of methods sensitive to the nature of the lowest-energy states is essential to arrive at a correct description of the states that are most relevant for the static and dynamic magnetic properties. The spectroscopic investigations also allowed for a full understanding of the magnetic relaxation processes occurring in this system. Thus, the importance of spectroscopic studies for the improvement of single-molecule magnets is underlined. [ABSTRACT FROM AUTHOR]

This work reports the broadband 2 μm emission from Ho 3+ /Er 3+ codoped germanosilicate glasses. Spectral components of the 2 μm emission band were analyzed and an equivalent model of four-level system was proposed to describe the 2 μm emission band. The results suggested that Ho 3+ /Er 3+ codoped germanosilicate glass has high effective emission bandwidth (172 nm), large emission cross section (5.18×10 −21 cm 2 ) and gain bandwidth (891×10 −28 cm 3 ), which is a promising candidate for 2 μm laser and amplifier. In addition, energy transfer mechanism between Ho 3+ and Er 3+ ions was investigated based on the measured fluorescence spectra and decay curves of Er 3+ : 4 I 11/2 and 4 I 13/2 levels. Energy transfer efficiency and microscopic parameters were calculated to evaluate the 2 μm fluorescence. Moreover, a rate equation model between Ho 3+ and Er 3+ ions was developed to elucidate 2 μm fluorescence behaviors. This work might provide useful guide to investigate fluorescence behavior and energy transfer mechanism of rare earth ions. [ABSTRACT FROM AUTHOR]

Tellurite glasses (TeO 2 –ZnO–La 2 O 3 ) doped with Er 3+ , Er 3+ /Ce 3+ and Er 3+ /Ce 3+ /Yb 3+ have been prepared using the melt-quenching technique, and the absorption spectra, fluorescence and up-conversion emission spectra together with the differential scanning calorimeter (DSC) curves and X-ray diffraction (XRD) patterns were measured to evaluate the effects of Ce 3+ and Yb 3+ introduction on the 1.53 µm band spectroscopic properties of Er 3+ , thermal stability and structural nature of glass hosts. The Judd–Ofelt intensity parameters Ω t ( t =2,4,6), spontaneous emission probabilities, radiative lifetimes and branching ratios of several Er 3+ transitions were calculated from the measured absorption spectra based on the Judd–Ofelt theory. The co-doping with Ce 3+ was effective on the suppression of up-conversion emission of Er 3+ owing to the phonon-assisted energy transfer: Er 3+ : 4 I 11/2 +Ce 3+ : 2 F 5/2 →Er 3+ : 4 I 13/2 +Ce 3+ : 2 F 7/2 , while the co-doping with Yb 3+ had the effect of obviously increasing the Er 3+ population at 4 I 11/2 level via the resonant energy transfer: Yb 3+ : 2 F 5/2 +Er 3+ : 4 I 15/2 →Yb 3+ : 2 F 7/2 +Er 3+ : 4 I 11/2 , both of which contributed the effective enhancement of 1.53 µm fluorescence emission. The quantitative studies were carried out to elucidate the energy transfer mechanism by calculating the microscopic parameters and phonon contribution ratios. The glass transition temperature ( T g ), crystallization onset temperature ( T x ) and the difference Δ T ( = T x − T g ) , which characterize the thermal stability of glass host, increased with the Ce 3+ and Yb 3+ co-doping and for all glass samples the value of Δ T is larger than 145 °C. The glass structural nature was demonstrated from the measured XRD patterns with no sharp diffraction peaks. The results of the present work indicated that the prepared Er 3+ /Ce 3+ /Yb 3+ co-doped tellurite glass is a potential material for developing broad-band and high-gain optical amplifiers and other optical devices. [ABSTRACT FROM AUTHOR]

Silver nanoparticles, placed on top of an Er3+ doped TiO2 thin film, were investigated as a means of achieving enhanced up-conversion. Finite-element modeling was used to determine the nanoparticle dimensions (height and diameter) yielding the largest plasmonic enhancement for an incident light wavelength of 808 nm. In order to mimic the experimentally observed up-conversion enhancement, the electric-field enhancement from the Ag nanoparticles was integrated over the entire thickness of the thin film. Based on these calculations, four samples were prepared and tested. The trends predicted by the models were found to correlate well with the trends of the experimentally obtained plasmonic enhanced up-conversion yields. The largest plasmonic enhancement for 808 nm excitation was observed for Ag nanoparticles of diameter 91 ± 5 nm and height 14 ± 1 nm, yielding 163- and 51-fold enhancements for the green (525 nm and 550 nm) and red (660nm) emissions peaks, respectively. [ABSTRACT FROM AUTHOR]

We report bright and dark rogue waves for a generalized nonlinear Schrödinger–Maxwell–Bloch model which describes the wave propagation in an inhomogeneous erbium doped fiber. This is achieved by reducing the inhomogeneous dynamical system to homogeneous dynamical model under certain parametric conditions (integrable conditions). We discuss the recurrence and annihilation of controllable bright and dark rogue waves as they propagate through a periodically distributed fiber-amplifier system. Furthermore, we investigate the nonlinear tunneling of these rogue waves as they propagate through a dispersion barrier or well. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate an ultra-wideband wavelength-tunable actively mode-locked short-cavity laser employing a 151-cm-long bismuth-based highly nonlinear erbium-doped fiber (Bi-HNL-EDF). A wavelength tuning range of 87nm from 1533nm to 1620nm can be achieved because the Bi-HNL-EDF has an ultra-wide gain bandwidth. High nonlinearity of the Bi-HNL-EDF also collaborates with spectral filtering by an optical bandpass filter to suppress the supermode noise quite effectively. Total length of the fiber ring cavity is as short as 16m. Thus, stable and clean 5.6–6.1ps pulses with a repetition rate of 10GHz are successfully obtained over the wavelength tuning range almost completely covering both the conventional wavelength band (1530–1565nm) and the longer wavelength band (1565–1625nm). The bismuth-based short-cavity fiber laser also shows good performance in the back-to-back bit-error-rate measurements, and maintains bit-error-free mode-locking operation throughout the entire wavelength tuning range. [Copyright &y& Elsevier]

ABSTRACT A new compact and low threshold mode-locked Erbium-doped fiber laser (EDFL) using nonadiabatic microfiber in conjunction with a graphene saturable absorber is demonstrated. The graphene was synthesized by electrochemical exfoliation of graphite at room temperature in 1% sodium dodecyl sulfate aqueous solution. Graphene flakes obtained from the process are mixed with polyethylene oxide as the host polymer to produce composite solution which acts as passive mode locker in the EDFL linear cavity. Mode-locked laser, with a threshold of less than 10 mW, pulse repetition rate of 55.8 MHz, and pulse duration of 0.82 ps, is achieved. The EDFL operates at around 1531.8 nm with an average output from 0.1 mW, pulse energy of 2 pJ at the 980 nm pump power of 10 mW. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1670-1673, 2014 [ABSTRACT FROM AUTHOR]

A tunable multiwavelength Brillouin-erbium fiber laser (MW-BEFL) using a twin-core fiber (TCF) coupler is proposed and demonstrated. The TCF coupler is formed by splicing a section of TCF between two single-mode fibers. By simply applying bending curvature on the TCF coupler, the peak net gain is shifted close to the Brillouin pump (BP), which has advantage for suppressing self-lasing cavity modes with low-BP-power injection. In this work, the dependency of the Stokes signals tuning range on the free spectral range (FSR) of TCF coupler is studied. It is also found that the tuning range of MW-BEFL can exceed the FSR of TCF coupler by adopting proper BP power and 980-nm pump power. Up to 40 nm tuning range of MW-BEFL in the absence of self-lasing cavity modes is achieved. [ABSTRACT FROM AUTHOR]

We built a mid-infrared time-domain spectroscopy (TDS) system optimized for the 8-12 μm spectral range based on a compact ultrafast Erbium:fiber laser that enables measurements of phase-resolved optical field transients directly in the time domain with high stability and spectral brightness. We achieved long term (>10 h) stability of the TDS signal by using a carrier-envelope-phase locking technique to reduce the timing jitter caused by environmental changes. Time domain measurements of the mid-infrared beam were achieved via electro-optic sampling in a GaSe crystal, using an ultrashort (∼15 fs) output of the fiber laser. Here, we present a full characterization of our TDS system including the dependence of the amplitude and pulse shape of the detected infrared waveforms on the thickness of the GaSe crystals. [ABSTRACT FROM AUTHOR]

A compact erbium-doped fibre (EDF) laser is demonstrated which uses a microfibre coupler and a highly concentrated EDF loop. The coupler functions to inject the pump light and tap out the output. The EDF laser operates at 1526.3 nm, with a signal-to-noise ratio of about 26 dB. The maximum output power 20 μW is obtained at the pump power 18.6 mW. We have obtained the slope efficiencies of the laser 0.12, 0.06, 0.04 and 0.02% at the EDF lengths fixed at 90, 78, 66 and 51 cm, respectively. The lowest lasing-pump power threshold is achieved at 3.8 mW. [ABSTRACT FROM AUTHOR]

We report the simultaneous growth of hexagonal AlB2-phase and tetragonal ThSi2-phase nanoislands of erbium silicide on the same silicon substrate. As a new technique, the patterned Si(001) surface with pits in a reverse-pyramid shape and {111} sidewalls is taken as the substrate template. The distribution of nanoislands reveals that the upward diffusion over surface steps plays an influential role on the location of islands. Si {111} facets on the pit sidewalls actually provide growth symmetry for the hexagonal islands. This work paves the way for exploring the intrinsic electrical transport properties of metal-semiconductor nanocontacts. [ABSTRACT FROM AUTHOR]

Highlights: [•] Er doped Si/Si1−xGe x /Si heterostructures have been prepared and characterized. [•] Luminescence, photoconductivity, PL excitation studies have been performed. [•] Erbium PL has been observed both under band-to-band and sub-bandgap excitation. [•] Excitation efficiency of Er ions has been investigated. [ABSTRACT FROM AUTHOR]

The Kerr nonlinearity behavior in an Er3+-doped ZrF4–BaF2–LaF3–AlF3–NaF optical fiber is investigated theoretically. It is found that by increasing the intensity of the coherent coupling field and in the presence of an incoherent pumping field, the enhanced Kerr nonlinearity with reduced absorption can be achieved at long wavelength, i.e.λ= 1550 nm, which is practical for communicational applications. In addition, it is found that the rate of incoherent pump field can significantly decrease the maximal Kerr nonlinearity of the medium. The impact of frequency detuning of the coherent field on linear and nonlinear susceptibilities is discussed. [ABSTRACT FROM PUBLISHER]

For more than 30 years, porcelain veneers have provided clinicians with a method for changing a patient's smile almost instantaneously. At times, however, veneers require replacement due to caries, fractures, or leakage or simply because the patient is unhappy with the esthetic outcome. Erbium hard tissue lasers can be used to efficiently, safely, and predictably remove all porcelain restorations while also keeping them in one piece. In doing so, this new tool for removing porcelain restorations provides clinicians with an alternative to high-speed handpieces while preventing further iatrogenic damage to underlying tooth structure. [ABSTRACT FROM AUTHOR]

Abstract: A tunable and switchable dual-wavelength Er-doped fiber ring laser using simultaneously forward and backward amplified spontaneous emissions is proposed and demonstrated experimentally at room temperature. A polarization-maintaining fiber Sagnac interferometer is used as a comb filter. This laser has eleven different output modes in the range of 1559–1566nm that can be switched flexibly from one to another. Single- and dual-wavelength lasers with a 3-dB linewidth of 0.7nm and optical signal-to-noise ratios of more than 28dB have a small tunable range. Spacing of dual-wavelength laser can be changed from 1.8nm to 0.8nm with the wavelength׳s increment. The laser shows good wavelength and peak power stabilities. [Copyright &y& Elsevier]

Abstract: The filterless erbium-doped fiber laser can generate continuous-wave broadband when highly nonlinear fibers are inserted into the cavity. In this work we demonstrate a linear cavity filterless erbium-doped fiber laser. The spatial-hole burning (SHB) effect in the linear cavity fiber laser is important for the CW broadband generation. When the pump power is 300mW, the bandwidth of the laser with SHB effect is 51.77nm while the bandwidth of the laser without SHB effect is 18.14nm. [Copyright &y& Elsevier]