Showing papers on "Erbium published in 1984"

Magneto-optic properties of rare earth iron garnet crystals in the wavelength range 1.1-1.7μm and their use in device fabrication

Abstract: The wavelength and temperature dependence of the Faraday rotation together with the optical loss spectra of yttrium, gadolinium, terbium, dysprosium, holmium, erbium and ytterbium iron garnets are reported for wavelengths in the range 1.1-1.7 mu m. It is demonstrated that the Faraday rotation of all the iron garnets decreases with increasing wavelength with the exception of ytterbium iron garnet which, for wavelengths in excess of approximately 1.3 mu m, possesses a wavelength independent Faraday rotation of 5.7+or-0.3 degrees mm-1. The performance of magneto-optic switches, isolators, modulators and deflectors constructed using each of these materials is discussed with particular emphasis on their operation at 1.3 mu m and 1.55 mu m, the wavelengths of interest in current optical fibre systems. It is concluded that whilst yttrium iron garnet or holmium iron garnet are best suited to the fabrication of devices operating at single wavelength, for broadband operation ytterbium iron garnet is to be preferred.

XPS characterization of erbium sesquioxide and erbium hydroxide

Abstract: The low temperature antiferromagnetic transition of Er2O3 is being investigated by studying the tunneling characteristics of superconducting junctions fabricated with artificial barriers of the oxide. To develop techniques for the semiquantitative determination of the relative concentrations of Er2O3 and Er(OH)3 in tunneling barriers, XPS studies have been carried out on standard samples of Er, Er2O3, and Er(OH)3.

Cooperative phenomena in yttrium erbium aluminum garnet crystals

Abstract: An investigation was made of the kinetics of the luminescence due to 4I11/2 → 4I15/2 and 4I13/2 → 4I15/2 transitions in the Er3+ ion in yttrium erbium aluminum garnet crystals subjected to strong resonant excitation argon laser radiation (λ = 4880 nm). The efficiency of the cooperative process resulting in nonlinear quenching of the luminescence from the 4I13/2 level and sensitization of the 4I11/2 level was estimated. The influence of this process on the kinetics of lasing as a result of the 4I11/2 → 4I13/2 transition (λ = 2.94 μ) was analyzed.

An Implementation of Dual Energy CT Scanning

Abstract: We have described a prereconstruction method for dual energy (PREDECT) analysis of CT scans. In theory, this method can (a) eliminate beam hardening and produce an accuracy comparable with monoenergetic scans and (b) provide the effective atomic number and electron density of any voxel scanned. Our implementation proves these statements and eliminates some of the objectionable noise. We constructed a phantom with a cylindrical sleeve-like compartment containing known amounts of high atomic number material simulating a removable skull. Conventional scans, with and without this beam hardener, were done of a water bath containing tubes of high electron and high atomic number material. Dual energy scans were then done for PREDECT. To increase the effective separation of the low and high energy beams by using more appropriate tube filtration, we fabricated a beam filter changer containing erbium, tungsten, aluminum, and steel. We used erbium, tungsten, and steel at high energy and aluminum, steel, and erbium at low energy for data acquisition. The reconstructions were compared visually and numerically for noise levels with the original steel only filtration. We found a decrease in noise down to approximately one-half the prior level when erbium/aluminum or tungsten/aluminum replaced the steel/steel filter. Erbium and tungsten were equally effective. Steel/erbium and steel/aluminum also significantly reduced image noise. The noise in the photoelectric (P) and Compton (C) images is negatively correlated. At any pixel, if the noise is positive in the P image, it is most probably negative in the C. Using this fact, the noise was reduced by postreconstruction processing.

Erbium silicide formation using a line‐source electron beam

Abstract: Rare‐earth silicide layers typically are heavily pitted when formed by furnace reaction of thin metal films with a silicon substrate. We show that this phenomenon can be explained by an inhibiting contamination layer which has a high activation energy for dissolution relative to that for silicide growth. Very smooth erbium silicide growth has been demonstrated by reacting the layers at much higher temperatures (1100–1300 K) for 200–500 μs, using electron beam heating. A novel combination of controlled electron beam heating, ion beam analysis, and computational simulation has been used to determine an activation energy for interface barrier dissolution of 3.7±0.3 eV.

A mass spectrometer study of the reaction of erbium with the residual gases in a vacuum coating unit and with heavy water

Abstract: A quadrupole gas analyser was used to study the gases inside a conventional diffusion-pumped vacuum evaporator prior to and following the evaporation of erbium. Studies have also been done on the effects of admitting heavy water (D 2 O) to the system. It has been found that erbium at the evaporation source reduces H 2 O and D 2 O to produce H 2 and D 2 respectively and that CO in the vacuum is converted to CH 4 in the presence of H 2 O. Various deuterated forms of CH 4 occur in the presence of H 2 O and D 2 O. An explanation is given of why vacuum-deposited films of erbium are frequently contaminated by ErH 2 in the presence of water even though Er 2 O 3 is thermodynamically much more stable than ErH 2 .

The MSR-investigation of antiferromagnetic phase transitions in erbium

Abstract: The muon spin relaxation rateΛ (T) in an orientated polycrystalline sample of erbium constructed of large monocrystals has been measured for temperatures 20

Laser light amplifier

Abstract: PURPOSE:To eliminate a complicated optical system in a device for amplifying a laser light of 1.5mum of wavelength by providing a glass optical fiber having Er and Yb in a core and an exciting light ray, thereby directly amplifying a signal light without applying the amplifying light. CONSTITUTION:A glass optical fiber 7 has a core 8 and a clad 9, the core 8 has an Er (Erbium) for oscillating a laser light of 1.5mum of wavelength when excited by high threshold value, and Yb (Ytterbium) operating as a sensitizer for exciting the Er when absorbing the light of narrow band near 1mum of wavelength. When the signal light is applied from a semiconductor laser 1 through a lens 1 to the fiber 7, the excited light of an arc lamp 6 is received to amplify the laser light (amplified light) of 1.5mum of wavelength oscillated from the Er by the exciting action of the Yb and to then output through a lens 2'.

Short-range-order structure of amorphous hydrous erbium oxide

Abstract: The hydrous lanthanide oxides comprise a complicated series of both crystalline and amorphous compounds. The amorphous short-range-order (SRO) phase of hydrous erbium oxide is the subject of this work. A thorough discussion of the instrumental arrangement and electronic counting chain for the X-radiation diffraction data collection is included. The scattering profiles for hydrous erbium oxide are shown and details of the ensuing data correction procedures are given. A radial distribution analysis of the calculated interference function, Si(S), was performed. SRO interatomic distances and the first-shell coordination number are reported. The mean Er-O bond distance is found to be 2.36 A and the erbium metal is nine coordinated. Comparison of the experimental radial distribution curve to ones calculated from crystalline systems lend credibility to the experimentally determined distances.

A dilatometric study of magnetic phase transitions in erbium

Abstract: As a result of a dilatometric investigation with a resolution of better than five parts per million, we can state that the Neel transition in erbium is second order. Results at the other phase transitions of erbium are also presented.

Energy parameters of lasers utilizing erbium glasses sensitized with ytterbium and chromium

Abstract: An experimental investigation was made of the effect of sensitizing ytterbium- and erbium-activated lead barium phosphate glasses with Cr3+ ions on the energy parameters of lasing due to the 4I13/2 — 4I15/2 transition in Er3+ ions (λ1 = 1.54 μ). It was found that substantial sensitization was achieved in phosphate glasses for only low concentrations of Cr3+ ions ( 0.07 wt.%) so that the efficiency of flashlamp-pumped erbium lasers could be improved by a factor of 1.5-4. The optimal conditions for achieving the best energy parameters of these lasers under free-lasing conditions were determined allowing for the spectral and energy distributions of the flashlamp radiation in the absorption range of the coactivator ions. By implementing these conditions using active elements 6 mm in diameter and 85 mm long, containing 17 wt.% Yb2O3, 0.25 wt.% Er2O3, and 0.07 wt.% Cr2O3, it was possible to achieve an efficiency of 1.2% for an electrical pump energy of 1 kJ. This was the highest efficiency achieved so far for erbium lasers. Measurements were made of the efficiency of transfer of the excitation energy from Cr3+ ions to Yb3+ ions at high levels of excitation of the medium.

The electric quadrupole transition L1M5(β9) in the X-ray emission spectrum of erbium

Abstract: A new diagram line corresponding to the electric quadrupole transition L 1 M 5 (β 9 ) in the X-ray emission spectrum of erbium is measured at λ = 1483.44 X . U . by means of a 40 cm curved mica crystal spectrograph of the transmission type.

Cross-relaxation effects in the luminescence of erbium at 1.5 μm

Abstract: This paper reports on the experimental and theoretical investigation of the influence of the processes of intercenter relaxation on the /sup 4/I/sub 13/2/ -->/sup 4/I/sub 15/2/ luminescence of erbium in polycrystalline yttrium oxychloride under resonance excitation The kinetics of the emission of samples with different concentrations of Er3/sup +/ ions were measured Numerical calculations of the dependence of the lifetime of the /sup 4/I/sub 13/2/ state on the erbium concentration for different values of the stationary excitation power were carried out The experimental dependence of the luminescence decay time on the concentration of the impurity ions constructed on the basis of data from kinetic measurements is interpreted on the basis of an examination of the cross-relaxation processes under the conditions of pairwise interactions It is determined that the power of the exciting radiation along with the concentration of the impurity ions is the main factor determining the role of intercenter relaxation in the luminescence of erbium along the /sup 4/I/sub 13/2/ -->/sup 4/I/sub 15/2/ channel due to the nonlinear nature of the dependence of the rate of the cross-relaxation processes which sum the electronic excitation acts on the flux density of the IR radiation

Electrical conduction of erbium fluoride thin films

Abstract: Thin-film capacitors of erbium fluoride were fabricated by electron beam gun deposition. The current-voltage characteristics of the erbium fluoride films were studied in the temperature range 323 to 396 K. For sufficiently high electric fields (>104 V cm−1), the leakage current increases exponentially with the square root of the applied field. Analysis of the data suggests an electrode-limited mechanism such as that suggested by Schottky. It is seen that the conduction mechanism is an activated process with the activation energy decreasing with increasing field.