Showing papers on "Erbium published in 2000"

Fiber-coupled microsphere laser.

Abstract: We demonstrate a 1.5-mm-wavelength fiber laser formed by placement of glass microsphere resonators along a fiber taper. The fiber taper serves the dual purpose of transporting optical pump power into the spheres and extracting the resulting laser emission. A highly doped erbium:ytterbium phosphate glass was used to form microsphere resonant cavities with large gain at 1.5 mm. Laser threshold pump powers of 60 mW and fiber-coupled output powers as high as 3 mW with single-mode operation were obtained. A bisphere laser system consisting of two microspheres attached to a single fiber taper is also demonstrated. © 2000 Optical Society of America

Exciton–erbium interactions in Si nanocrystal-doped SiO2

Abstract: The presence of silicon nanocrystals in Er doped SiO2 can enhance the effective Er optical absorption cross section by several orders of magnitude due to a strong coupling between quantum confined excitons and Er. This article studies the fundamental processes that determine the potential of Si nanocrystals as sensitizers for use in Er doped waveguide amplifiers or lasers. Silicon nanocrystals were formed in SiO2 using Si ion implantation and thermal annealing. The nanocrystal-doped SiO2 layer was implanted with different doses of Er, resulting in Er peak concentrations in the range 0.015–1.8 at. %. All samples show a broad nanocrystal-related luminescence spectrum centered around 800 nm and a sharp Er luminescence line at 1536 nm. By varying the Er concentration and measuring the nanocrystal and Er photoluminescence intensity, the nanocrystal excitation rate, the Er excitation and decay rate, and the Er saturation with pump power, we conclude that: (a) the maximum amount of Er that can be excited via exc...

1.54 μm infrared photoluminescence and electroluminescence from an erbium organic compound

Abstract: Infrared emission at 1.54 μm excited optically and electrically from an erbium organic compound tris(acetylacetonato)(1,10-phenanthroline) erbium [Er(acac)3(phen)] is observed. The rare-earth complex is dispersed into a polymer matrix of poly(N-vinylcarbazole) (PVK) to fabricate an electroluminescent (EL) device with an ITO/PVK:Er(acac)3(phen)/Al:Li/Ag structure, where ITO represents indium–tin–oxide-coated glass. The device shows infrared EL emission at 1.54 μm, which suggests a simple and cheap method to obtain a light source for 1.54-μm-wavelength devices in optical communications.

A 40-GHz 850-fs regeneratively FM mode-locked polarization-maintaining erbium fiber ring laser

Abstract: An 850-fs pulse train at 40 GHz was directly generated from a regeneratively FM mode-locked fiber laser. The soliton effect was used to generate a short pulse and to suppress the supermode noise. The laser was locked to an external signal by a phase-locked loop (PLL) technique and the wavelength was tunable between 1540 and 1555 mn.

High photoluminescence in erbium-doped chalcogenide thin films

Abstract: The spectral properties of the chalcogenide glasses As2S3 and As24S38Se38-doped with Er3+ are presented and discussed. Thin films were formed by thermal evaporation and the erbium doping was obtained by subsequent ion implantation. Strong Er3+ emission at 1.54 μm has been observed. The high refractive index of these chalcogenide glasses lead to Er3+ emission cross-sections (15×10 −21 cm 2 ) which are two times higher than for doped silica glass. The lifetime of the Er3+ metastable 4I13/2 energy level was measured to be 2.3 ms. This short lifetime is consistent with the high emission cross-section. Furthermore, the very low phonon energies of chalcogenide glasses lead to relatively long lifetimes of the Er3+ 4I11/2 pump level, which have been measured to be of the order of 0.25 ms. These spectral properties make this glass a good candidate for applications in the field of integrated optics.

Erbium emission from porous silicon one-dimensional photonic band gap structures

Abstract: We report tunable, narrow, directional, and enhanced erbium emission from one-dimensional photonic band gap structures. The structures are prepared by anodic etching of crystalline silicon and consist of two highly reflecting porous silicon Bragg reflectors sandwiching an active layer. The cavities are doped by cathodic electromigration of the erbium ions into the porous silicon matrix, followed by high temperature oxidation. By controlling the oxidation temperature of the structure, the position of the erbium emission near 1.5 μm is tuned to regions where the natural erbium spectrum is very weak. The erbium emission from the cavity is narrowed to a full width at half maximum of 12 nm with a quality factor Q of 130, highly directional with a 20° emission cone around the normal axis, and enhanced by more than one order of magnitude.

40 GHz actively modelocked polarisation maintaining erbium fibre ring laser

Abstract: The first polarisation-maintaining actively modelocked erbium fibre ring laser (ML-EFRL) operating at a base rate of 40 GHz is presented. The laser generates highly stable and virtually transform-limited 1.2–1.9 ps pulses tunable over 40 nm with a timing jitter of < 0.1 ps. These represent the shortest pulses and lowest timing jitter generated by a 40 GHz ML-EFRL.

Sol-Gel Fabrication of Rare-Earth Doped Photonic Components

Abstract: The use of sol-gel to fabricate silica-on-silicon waveguides, and particularly erbium-doped waveguide amplifiers, is reviewed. In particular, efforts to use sol-gel to improve molecular homogeneity in heavily Er-doped silica-based films is discussed. A variety of material studies carried out to investigate the gain limitations found in these materials is then presented. These include x-ray diffraction, ellipsometry and Rutherford backscattering. Excess heat treatment is used to force crystallisation of the films, and analysis of the resulting structure is used to infer properties of the glass before the additional heating. The use of erbium alkoxide precursors is shown to alter the erbium environment in the final glass, in comparison to the use of inorganic erbium salts.

Erbium-ytterbium waveguide laser mode-locked with a semiconductor saturable absorber mirror

Abstract: Picosecond pulses are produced using a semiconductor saturable absorber mirror in a laser based on an Er-Yb codoped planar waveguide amplifier. Continuous-wave mode-locking (CWML) with 9.8-ps pulses is obtained at repetition rates up to 100 MHz. With intracavity spectral filtering, saturable pulsewidths of 1 ps are achieved, and tunable picosecond pulses are obtained from 1534 to 1553 nm. Absorber characterization suggests that two-photon absorption within the saturable absorber mirror influences the CWML stability.

Model of temperature dependence for gain shape of erbium-doped fiber amplifier

Abstract: The problem of modeling the temperature dependence of erbium-doped fiber amplifier (EDFAs) is important for multichannel optical WDM systems. A physical model is presented in this paper, which could be used to predict the gain change under temperature variations for such systems. Some of the input parameters for the model are the erbium energy sublevel density, excitation coefficients from lower sublevels to upper sublevels of erbium ions, and electron distribution over energy levels. It is difficult to measure these parameters. In order to use the model for gain shape calculations, some simplifications are demonstrated. These simplifications lead to two numerical models, which are shown to be consistent with experimental data with reasonable accuracy, and are based only on two spectral measurements for different temperatures. Both numerical models were tested for the signal band and the 980 nm pump band of a typical erbium-doped fiber.

80 nm spectrally flattened, high power erbium amplified spontaneous emission fibre source

Abstract: A novel two-stage spectrally flattened, high output power erbium amplified spontaneous emission (ASE) fibre source pumped using a single laser diode pump is reported. The source has a bandwidth of 80 nm with a 1 dB ripple and output power of +13 dBm (20 mW).

Size control of erbium-doped silicon nanocrystals

Abstract: This work describes the effects of pyrolysis oven length and erbium precursor on the preparation of discrete erbium-doped silicon nanoparticles. These doped nanoparticles were prepared by the co-pyrolysis of disilane and the volatile complex Er(tmhd)3 (tmhd=2,2,6,6-tetramethyl-3,5-heptanedionato). The particle sizes and size distributions were determined using high resolution and conventional transmission electron microscopy. Erbium-doped silicon nanoparticles exhibit a selected area electron diffraction pattern consistent with the diamond cubic phase and a distinctive dark contrast in the transmission electron microscope. The presence of erbium is confirmed by x-ray energy dispersive spectroscopy. In general, the mean diameter of the individual nanoparticles increases as the length of the pyrolysis oven used during their preparation is increased.

Gain flattened L-band EDFA based on upgraded C-band EDFA using forward ASE pumping in an EDF section

Abstract: A novel method is presented for implementing an L-band erbium doped fibre amplifier (EDFA) making use of forward amplified spontaneous emission pumping, from a commercially available C-band EDFA, in an erbium doped fibre. Tuning of the length of erbium doped fibre enables a flat gain characteristic to be obtained with a low noise figure over the entire L-band window.

Numerical analysis of multifrequency erbium-doped fibre ring laser employing periodic filter and frequency shifter

Abstract: Numerical analysis of a recently proposed multifrequency erbium-doped ring laser employing a frequency periodic filter and frequency shifter is presented. The model is based on a homogeneously broadened three-level approximation of an erbium ion. The multifrequency operation is achieved by shifting the frequency of the amplified spontaneous emission (ASE) power circulating in the ring cavity by one wavelength slot each circulation period to prevent steady-state single-frequency laser operation. The effect of cavity loss, erbium-doped fibre (EDF) gain, direction of ASE circulation on lasing spectrum uniformity and output power is investigated.

Erbium/ytterbium fluorescence based fiber optic temperature sensor system

Abstract: Erbium/ytterbium co-doped fibers have been investigated in this work for the first time to determine their potential in thermometry applications based on the use of fluorescence decay. Several samples have been used and their performance characteristics determined. These have included studies of fiber annealing as well as thermal cycling tests and it was found that unlike other rare-earth ion doped fibers previously studied, such as Nd3+, Er3+, or Tm3+ doped fibers, the Er/Yb co-doped samples used here have shown a much smaller degree of thermal annealing when their thermal characteristics have been evaluated and compared. The response of the thermometer and the error in the measurement was found to be, at <±5 °C, within the stability of the oven used in the tests over a wide temperature range from 0 to 850 °C.

Efficient high power operation of erbium 3 µm fibre laser diode-pumped at 975 nm

Abstract: Efficient CW operation of a 2.71 um Er,Pr:ZBLAN double-clad fibre laser pumped with a single diode laser operating at a wavelength of 975 nm is described. A maximum output power of 0.5 W and a slope efficiency of 25% (with respect to the launched pump power) were obtained. Threshold pump powers of < 200 mW launched were measured and consistent relaxation oscillations in the output from the fibre laser indicate the presence of a saturable absorption mechanism.

Method for controlling dopant profiles

Abstract: The present invention discloses novel methods for fabricating glass articles, particularly optical fiber glass preforms, which may contain alumina, yttrium, lanthanum, erbium, or other rare earth metals as dopants. The glass articles made in accordance with the present invention exhibit radially uniform dopant profiles relative to conventional dopant methods. In addition, the overall concentration of the dopant is increased relative to analogous dopant methods.

Erbium-doped microspherical lasers at 1.56 [micro sign]m

Abstract: Experimental results on the realisation and spectral characterisation of Er-ZBLAN microspherical lasers at 156 µm are presented The laser effect is obtained using the properties of whispering gallery modes and pumping at 148 µm Multimode operation and a laser threshold as low as 600 µW have been observed

Debye temperature of erbium-doped yttrium aluminum garnet from luminescence and Brillouin scattering data

Abstract: Erbium-doped yttrium aluminum garnet (YAG) has been investigated by Brillouin scattering and photoluminescence (PL) spectroscopy in wide temperature (77–500 K) and erbium concentration (0.1%–50%) ranges. A characteristic temperature Θ, connected to the Debye temperature, has been evaluated by two different methods: from the thermal shifts and broadening of PL spectral lines, and from the elastic constants, estimated by Brillouin scattering. Both methods show that the Debye temperature weakly depends on the doping level (up to 50 at.%) of the erbium ions. This means that YAG is an ideal host for erbium ions; this result is relevant for application of rare earth elements in YAG crystal in the fields of telecommunications and optical devices.

Effect of yttrium and erbium ion implantation on the oxidation behaviour of the AISI 304 austenitic steel

Abstract: The beneficial effect of the addition of yttrium and erbium by ion implantation on the oxidation behaviour of AISI 304 stainless steel at 1173 K has been investigated. Isothermal oxidation tests have been conducted for up to 500 h. The effect of ‘rare earth elements’ (REE) have been studied previously in order to enhance the oxidation behaviour of different alloys. The results show that yttrium and erbium have similar effects, reducing the rate of continuing scale growth and inhibiting scale failure processes. It is concluded in this study, that both reactive elements inhibit the growth of the poorly protective and adherent oxides rich in iron and chromium, which help the spalled behaviour, together with a smaller oxide grain size.

Tellurite glasses and optical components

Abstract: A family of tellurite glasses and optical components for telecommunication systems, the glasses consisting essentially of, as calculated in cation percent, 65-97 % TeO2, and at least one additional oxide of an element having a valence greater than two and selected from the group consisting of Ta, Nb, W, Ti, La, Zr, Hf, Y, Gd, Lu, Sc, Al and Ga, that may contain a lanthanide oxide as a dopant, in particular erbium oxide, and that, when so doped, is characterized by a fluorescent emission spectrum having a relatively broad FWHM value.

Strain and temperature effects on Erbium-doped fiber for decay-time based sensing

Abstract: An experimental investigation into the strain and temperature sensitivity of the fluorescence decay time in commercial erbium-doped optical fiber has been carried out. Results show that a strain effect on the performance of temperature-based sensors using such fiber is larger than that for neodymium-doped fiber, but a little smaller than is seen in similar ytterbium-doped material. For the materials studied, the relative change in lifetime ranges from about 5×10−7 (for Yb) to 14×10−7 (for Nd) μe−1 and the associated error in the temperature measurement ranges from 1.8×10−3 (for Nd) to 6.1×10−3 Kμe−1 for the Yb sample used. The application to simultaneous strain and temperature monitoring is discussed.

Exciting erbium-doped planar optical amplifier materials

Abstract: Erbium-doped planar optical amplifiers can find numerous applications in photonic integrated circuits operating at 1.5 micrometers . The challenge is to fabricate these devices with high gain, operating at low pump power, and having small overall size. In this paper a review is given of our recent work in the area of Er-doped waveguide materials and amplifiers based on three materials classes: oxide films (Al2O3, Y2O3, SiO2), polymers, and silicon.

1.54 μm Er3+ photoluminescent and waveguiding properties of erbium-doped silicon-rich silicon oxide

Abstract: 1.54 μm Er3+ photoluminescent and waveguiding properties of erbium-doped silicon-rich silicon oxide (SRSO) are investigated. Optimum Er3+ luminescence was obtained after an anneal of at least 5 min at 950 °C, and at least 1 at. % excess silicon in SRSO was necessary for the excitation of erbium to be dominated by carriers. The refractive index and the bulk waveguide loss of erbium-doped SRSO film with 0.1 at. % erbium and 1 at. % excess silicon after the optimal anneal treatment was 1.4817 and 4.0 dB/cm, respectively. Fabrication of an erbium-doped SRSO strip waveguide using the standard Si processing techniques and the guiding of internal 1.54 μm Er3+ emission by such a strip waveguide are demonstrated.

Simple and accurate procedure for modeling erbium-doped waveguide amplifiers with high concentration

Abstract: We present an accurate, fast, and easily implemented procedure for modeling erbium-doped waveguide amplifiers (EDWAs) with high concentration doping level. The model is shown to be in a very good agreement when compared with experimental results, and is used in a detailed analysis of a waveguide amplifier with 980-nm pumping.

Efficient up-conversion pumping at 800 nm of an erbium-doped fluoride fibre laser operating at 850 nm

Abstract: An erbium-doped fluorozirconate fibre laser has been constructed which uses up-conversion pumping at 801 nm to excite a higher-level laser transition at 850 nm. A slope efficiency of 38% was measured.