Showing papers on "Erbium published in 2001"

Optical gain at 1.54 μm in erbium-doped silicon nanocluster sensitized waveguide

Abstract: Optical gain at 1.54 μm in erbium-doped silicon-rich silicon oxide (SRSO) is demonstrated. Er-doped SRSO thin film was fabricated by electron-cyclotron resonance enhanced chemical vapor deposition of silicon suboxide with concurrent sputtering of erbium followed by a 5 min anneal at 1000 °C. Ridge-type single mode waveguides were fabricated by wet chemical etching. Optical gain of 4 dB/cm of an externally coupled signal at 1.54 μm is observed when the Er is excited via carriers generated in the Si nanoclusters by the 477 nm line of an Ar laser incident on the top of the waveguide at a pump power of 1.5 W cm−2.

Spectroscopic and lasing properties of Er3+:Yb3+-doped fluoride phosphate glasses

Abstract: Er 3+ emission and lasing properties at 1.5 µm were studied in fluoride phosphate glasses (FP20) with different doping concentrations as well as in a commercial phosphate glass (Kigre QX). Emission decay behaviour at 1 µ ma nd 1.5 µm was examined with respect to energy transfer be- tween ytterbium and erbium. Emission cross-sections were determined using the reciprocity and Fuchtbauer-Ladenburg methods. Gain spectra were calculated for the glasses and related to differences in the tuning curves and lasing prop- erties. The temperature rise due to the quantum defect was determined via the ratios of green upconversion luminescence for different pump powers. The results from the laser and tuning experiments indicate that the FP20 glass offers good possibilities in broadband amplification and the generation of ultrashort pulses.

Widely tunable erbium-doped fiber ring laser covering both C-band and L-band

Abstract: We demonstrate a widely tunable erbium-doped fiber (EDF) ring laser covering both the conventional wavelength band (C-band) and the long wavelength band (L-band). It features a wide tunable range, high output power, low-coherent, and depolarized output. A tunable range over 80 nm (1520-1600 nm) has been achieved by optimizing the length of the EDF and by using an intracavity fiber Fabry-Perot (FFP) filter.

A broadly tunable erbium-doped fiber ring laser: experimentation and modeling

Abstract: Broad-band tunability of erbium-doped silica fiber ring lasers in the 1.48-1.62 /spl mu/m wavelength band is demonstrated through modeling and experiment. Tunability over the erbium-doped fiber amplifier (EDFA) C- and L-bands is achieved with a simple laser design using a single gain medium working in deep saturation. A comprehensive numerical model based on an iterative solution of propagation rate equations and spectrally resolved Giles parameters was used to analyze the impact of various laser variables. The dependence of laser output power on total cavity loss, erbium-doped fiber length, pump power, and lasing wavelength has been investigated. The calculated laser characteristics have been found in good quantitative agreement with the experimentally obtained data. Experimental results concerning wavelength tunability, output power, and lasing wavelength repeatability/stability and spectral purity are also presented.

Erbium as a probe of everything

Abstract: Erbium is a lanthanide ion with unique electronic and optical properties. In its trivalent state it is composed of an incompletely filled 4f inner shell and two closed outer shells. By employing these properties in specific material systems, Er can be used to probe point defects, oxygen, OH, Er, radiation defects, network structure, excitons, optical density of states, optical modes, and photonic bandstructure.

Offset phase locking of Er,Yb:glass laser eigenstates for RF photonics applications

Abstract: An optical source of microwaves with very low phase noise for communications and radar systems is realized and tested. It is obtained by dual-frequency operation of a diode pumped Er,Yb:glass laser. An electrooptic crystal inserted inside the resonator permits both to tune the frequency difference between orthogonally polarized eigenstates, and to turn the laser into a voltage controlled oscillator. An optical phase-locked loop is then implemented in the GHz range, resulting in a measured instrument limited 3 dB-linewidth of 10 Hz. The phase noise is shown to be -100 dBc/Hz at 10-kHz offset.

Three-photon phenomena in the upconversion luminescence of erbium–ytterbium-codoped phosphate glass

Abstract: Frequency upconversion into green and red luminescence in erbium–ytterbium-codoped phosphate glass pumped with a 970 nm diode laser is presented. The red upconversion emission results from a two-photon excitation process. The green emission results from a two- or three-photon excitation process with the two-photon process dominating at low pumping power. Based on measurement of the excitation and emission spectra, a model of the three-photon excitation process has been developed. This model provides a good basis for explaining the effect of the three-photon process on the saturation of 1.54 μm laser power of Er, Yb-codoped phosphate glass laser.

Ultrashort-pulse source with controllable multiple-wavelength output

Abstract: A multiple-wavelength ultrashort-pulse laser system includes a laser generator producing ultrashort pulses at a fixed wavelength, and at least one and preferably a plurality of wavelength-conversion channels. Preferably, a fiber laser system is used for generating single-wavelength, ultrashort pulses. An optical split switch matrix directs the pulses from the laser generator into at least one of the wavelength conversion channels. An optical combining switch matrix is disposed downstream of the wavelength-conversion channels and combines outputs from separate wavelength-conversion channels into a single output channel. Preferably, waveguides formed in a ferroelectric substrate by titanium indiffusion (TI) and/or proton exchange (PE) form the wavelength-conversion channels and the splitting and combining matrices. Use of the waveguide allows efficient optical parametric generation to occur in the wavelength-conversion channels at pulse energies achievable with a mode-locked laser source. The multiple-wavelength laser system can replace a plurality of different, single-wavelength laser systems. One particular application for the system is a multi-photon microscope, where the ability to select the ultrashort-signal wavelength of the laser source accommodates any single fluorescent dye or several fluorescent dyes simultaneously. In its simplest form, the system can be used to convert the laser wavelength to a more favorable wavelength. For example, pulses generated at 1.55 μm by a mode-locked erbium fiber laser can be converted to 1.3 μm for use in optical coherence tomography or to 1.04-1.12 μm for amplification by a Yterbium amplifier, allowing amplification of pulses which can be used in a display, printing or machining system.

Erbium 3 /spl mu/m fiber lasers

Abstract: With its recent breakthrough in terms of output power the erbium 3-/spl mu/m fiber laser has become an object of intense scientific research and an increasingly attractive tool for medical applications. The paper reviews the research on the erbium 3-/spl mu/m fiber laser since its first demonstration. Its development is seen in relationship to the early success of the corresponding crystal laser system, to the foundations that were laid by the investigation of its spectroscopy and population mechanisms, and the recent technological developments in related fields.

Exciton–erbium energy transfer in Si nanocrystal-doped SiO2

Abstract: Silicon nanocrystals were formed in SiO2 using Si ion implantation followed by thermal annealing. The nanocrystal-doped SiO2 layer was implanted with Er to peak concentrations ranging from 0.015 to 1.8 at.%. Upon 458 nm excitation, a broad nanocrystal-related luminescence spectrum centered around 750 nm and two sharp Er luminescence lines at 982 and 1536 nm are observed. By measuring the temperature-dependent intensities and luminescence dynamics at a fixed Er concentration, and by measuring the Er concentration dependence of 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: (1) the Er is excited by excitons recombining within Si nanocrystals through a strong coupling mechanism; (2) the exciton‐Er energy transfer rate is \10 6 s 1 ; (3) the exciton‐Er energy transfer efficiency is\60 %; (4) each nanocrystal can have at most 1‐2 excited Er ions in its vicinity, which is attributed to either an Auger de-excitation or a pair-induced quenching mechanism; (5) at a typical nanocrystal concentration of 10 19 cm 3 , the maximum optical gain at 1.54 mm of an Er-doped waveguide amplifier based on Si nanocrystal-doped SiO2 is 0.6 dB cm 1 ; (6) the effective Er excitation cross-section using this nanocrystal sensitization scheme is seff:10 15 cm 2 at 458 nm, which is a factor 10 5 ‐10 6 larger than the cross-section for direct optical pumping of Er. This enables the fabrication of an Er-doped nanocrystal waveguide amplifier that can be pumped using a white light source. © 2001 Elsevier Science S.A. All rights reserved.

Titanium dioxide film co-doped with yttrium and erbium and method for producing the same

Abstract: A precursor composition of TiO2 doped with erbium (Er) and yttrium (Y) for forming a film used in a planar optical waveguide amplifier. The precursor composition includes 100 mol % TiO2 precursor compound, about 0.1-10 mol % erbium ion (Er3+) precursor compound, and about 1-50 mol % yttrium ion (Y3+) precursor compound, thereby forming a doped TiO2 film co-doped with erbium and yttrium an amorphous structure to achieve the enhancing effect on photoluminescence properties.

Erbium-activated silica xerogels: spectroscopic and optical properties

Abstract: Silica-based sol–gel glasses activated by Er3+ ions are attractive materials for integrated optics (IO) devices such as frequency upconverters and optical amplifiers. Monolithic erbium-activated silica xerogels with erbium content ranging from 0 up to 40 000 ppm were prepared by the sol–gel technique. Samples were densified by thermal treatment in air at 950°C for 120 h. The densification degree and the relative content of hydroxyl groups were studied by Raman spectroscopy. Refractive indices were measured at 632.8 and 543.5 nm by a prism coupling technique. Green to blue and violet upconversion luminescence upon continuous-wave excitation at 514.5 nm was observed for all samples. Emission at 1.5 μm , characteristic of the 4 I 13/2 → 4 I 15/2 transition of Er3+ ions, was observed at room temperature for all samples upon continuous-wave excitation at 980 nm. For the 5000 Er/Si ppm-doped xerogel, a photoluminescence was observed and a lifetime of 8 ms for the metastable 4 I 13/2 level was measured.

Planar Er- and Yb-doped amplifiers and lasers

Abstract: New results in erbium-doped planar waveguide amplifiers and lasers are presented. The waveguides are produced in silica-on-silicon technology using plasma-enhanced chemical vapor deposition. Waveguide propagation losses outside the erbium absorption band are improved to values below 0.05 dB/cm for a core–cladding index step of around 1.4%. Amplifier arrays show a net gain of more than 12 dB over the entire C-band.

High gain short length phosphate glass erbium-doped fiber amplifier material

Abstract: An internal gain of 10 dB (975 nm pumping) has been demonstrated from a 2.2 cm long section of experimental fiber manufactured from Kigre's "MM-2" Er,Yb:phosphate laser glass. As much as 26 dB (1480 nm pumping) of gain Was produced from this same experimental fiber with an 8.8 cm length. Images of the 1.54 /spl mu/m mode field containment for this fiber indicate a perfect match to standard communications transmission fiber.

Exciton–erbium coupling and the excitation dynamics of Er3+ in erbium-doped silicon-rich silicon oxide

Abstract: The exciton–erbium coupling and the excitation dynamics of Er3+ in erbium-doped silicon-rich silicon oxide are investigated using time-resolved measurements of Er3+ luminescence. The dependence of the Er3+ luminescence on the pump power and duration indicates that the exciton–erbium coupling is dominant over carrier–exciton coupling. The results further support the idea that the luminescent Er3+ ions are not in the Si nanoclusters but in the interface region surrounding the nanoclusters.

Diode-pumped erbium-ytterbium-glass laser passively Q-switched with a PbS semiconductor quantum-dot doped glass

Abstract: Q-switched and cw operation of different diode-pumped erbium-ytterbium doped glasses at 1.5 μm has been studied in a compact microlaser setup. For Q-switching we used a novel PbS semiconductor quantum-dot doped glass which offers low saturation intensity compared with typical absorbers used and a fast time response. The cw laser delivered output powers of 35 mW with slope efficiencies of 16%. In Q-switched operation pulse energies of 1 μJ at repetition rates of 1–2 kHz and pulse durations of about 30–50 ns, depending on absorber thickness were obtained.

Photoluminescence performance of pulsed-laser deposited Al2O3 thin films with large erbium concentrations

Abstract: Erbium doped Al2O3 films with concentrations up to 6×1020 Er cm−3 have been prepared in a single step process by pulsed-laser deposition. Alternate ablation of Al2O3 and Er targets has been used to control the in-depth distribution and in-plane concentration of Er3+ ions independently. The characteristic Er3+ photoluminescence response at 1.53 μm has been studied as a function of the Er3+ distribution. It is found that lifetime values can be greatly increased by increasing the Er3+–Er3+ in-depth separation above 3 nm. This result can be related to a reduced Er3+–Er3+ energy migration process. The in-plane Er3+ concentration was increased by either increasing the number of pulses on the Er target or the laser energy density for ablation. By the latter method in-plane concentrations as high as 1.1×1014 Er cm−2 per layer (corresponding to 2×1020 Er cm−3) were achieved, while keeping lifetime values as high as 6 ms. This result is explained in terms of shallow Er3+ implantation during deposition.

Bandpass filters based on π-shifted long-period fiber gratings for actively mode-locked erbium fiber lasers

Abstract: We have fabricated bandpass filters based on π-shifted long-period gratings for application in actively mode-locked erbium fiber lasers. Introducing the π-phase shift in the middle of the grating opens a bandpass within the core–cladding mode resonance peaks. With a 22-nm bandwidth filter inserted in an actively mode-locked erbium fiber sigma laser, solitonlike pulses are generated, with a power-dependent duration of ≈3–5 ps, at a 3-GHz repetition rate. These all-fiber filters have the advantages of low insertion loss <0.5 dB and a wide bandwidth (10–20 nm), and they do not require that a circulator be inserted into the laser cavity.

Modified spontaneous emission in erbium-doped SiO2 spherical colloids

Abstract: Spherical SiO2 colloids with two different diameters (175 nm, 340 nm) were doped with erbium at different concentrations The spheres show sharply peaked photoluminescence centered at 1535 μm, due to intra-4f transitions in Er3+ From measurements of the Er decay rate for different Er concentrations the decay rate of isolated Er ions (ie, in absence of concentration quenching) was determined for the two colloid diameters The data were compared to spontaneous emission rates derived from calculations of the local optical density of states in the colloids The calculation predicts a large difference in the spontaneous emission rate for both colloid sizes (61 vs 40 s−1), in perfect agreement with the measured data

Silver sensitized erbium ion doped planar waveguide amplifier

Abstract: A material for use in optical amplifiers is described. The material includes an oxide glass substrate material, a rare earth dopant and a silver dopant. The silver dopant enhances photoluminescence of the rare earth dopants in the oxide glass. The silver can be introduced into the glass using an ion exchange process or by ion implantation. Oxide glass doped with erbium ions and silver ions provides a broad excitation band for photoluminescence of Er 3+ in the visible and near ultraviolet. An amplifier material according to the present invention can be formed by ion implanting a rare earth ion, for example erbium, and doping with silver by an ion exchange method. Alternatively, the silver can be implanted into the material as well. The resulting silver dopant may be dispersed throughout the oxide glass primarily as ions as a result of the fabrication method.

Gain and noise in ytterbium-sensitized erbium-doped fiber amplifiers: measurements and simulations

Abstract: The fiber gain and noise figure in erbium (Er)-ytterbium (Yb) codoped fiber amplifiers are experimentally studied and theoretically modeled. The different fiber parameters for the model are found in separate characterization measurements. The comparison between the measured and calculated data show excellent agreement. In addition, we demonstrate the design process for a specific cladding-pumped fiber to find the optimum fiber length.

Fabrication and optical properties of neodymium-, praseodymium- and erbium-chelates-doped plastic optical fibres

Abstract: Neodymium, praseodymium and erbium ions are successfully incorporated into the core of deuterated polymer-based optical fibres. The spectra of three fibres have several strong absorption bands in the visible and infrared regions. The fluorescence lifetime (6.24 /spl mu/s) at 1060 nm of Nd-chelate doped plastic optical fibre with an uncooled photodiode is obtained.

Green up-conversion of Er3+ in KGd(WO4)2 crystals. Effects of sample orientation and erbium concentration

Abstract: Pumping with infrared light resonant to the energy position of 4 I 11/2 and 4 I 9/2 multiplets respectively has excited green up-conversion of Er3+ in KGd(WO4)2 single crystal. At room temperature the maximum green-emission intensity is achieved by pumping with light polarized parallel to the C2 symmetry axis of the crystal (//p) at 981 and 801.5 nm, while pumping with light parallel to the principal m axis (//m) has maximum up-conversion at 978.2, 806 and 800 nm. The emission is weakly polarized. The maximum of the emission peaks at 547.8 nm if the light is analyzed parallel to the C2 axis or at 552.4 nm for light perpendicular to it. The largest emission intensity was achieved with an erbium concentration about 3×1020 cm-3. A schematic model of the up-conversion process is suggested.

Aluminum Oxide Doped with Erbium, Titanium and Chromium for Active Integrated Optical Applications

Abstract: Summary Amorphous thin films with very low attenuation are grown by MO-PECVD. The modifications due to the annealing condition are subject of investigations. Aluminum oxide waveguides are doped with erbium for applications in telecommunication to develop an integrated optical amplifier. AlsoAl 2 O 3 doped with transition elements to develop tunable solid state lasers for spectroscopic measurements is of interest. Lasers with broadest fluorescence bands are Ti:Sapphire lasers or chromium doped specific crystals or glasses. In this paper the suitability of titanium and chromium doped aluminum oxide material as laser material is examined. Titanium and chromium doped waveguides have been annealed. Their fluorescence and lifetime measurements are presented.

EXAFS studies on erbium-doped TiO2 and ZrO2 sol–gel thin films

Abstract: High concentration (15% in a molar ratio) Er-doped TiO 2 and ZrO 2 sol–gel layers, annealed under an oxygen flow, at 300 and 650 °C, respectively, were studied at the erbium L III edge (8358 eV) by X-ray near edge structure spectroscopy (XANES) and extended X-ray absorption fine structure spectroscopy (EXAFS) in order to obtain some useful information about the local atomic arrangement around the incorporated rare earths. Transmission electronic microscopy (TEM) experiments were also carried out in order to support the X-ray absorption spectroscopy (XAS) studies by a knowledge of the global structure of the sol–gel layer. The analysis of the XAS data reveals that, in the case of an annealing treatment at 300 °C, the local atomic structure surrounding the erbium ion appears amorphous for both samples, while after an annealing treatment at 650 °C, a crystalline structure around the dopant is strongly dependent on the nature of the lattice cation (Ti or Zr). Indeed, for such an annealing temperature, the local atomic environment around the erbium ion appears to be amorphous in the case of an anatase matrix while it seems to have crystallized around the dopant in the case of zirconia. Furthermore, for both these compounds the XAS data reveal that a pairing effect between the erbium ions probably occurs. The TEM studies performed on the samples annealed at 650 °C show the appearance of other phases different from the matrix, confirming this fact. For both compounds, the analysis of these sets of data reveals that the erbium ion has not formed metallic erbium in the matrix. For the Er-doped TiO 2 sol–gel layers, it can be concluded that the rare earth has not precipitated in the form of erbium oxide clusters. Whereas, for the Er-doped ZrO 2 sol–gel layers, nothing can be deduced about the possible appearance of Er 2 O 3 . It can be then concluded that the appearance of another phase, with the formula near Zr 3 Er 4 O 12 , likely occurs in the case of the Er-doped ZrO 2 sol–gel layer annealed at 650 °C, while a solid solution of Er x Ti y O z was formed in the case of the Er-doped TiO 2 sol–gel layer (annealed at 650 °C). Nevertheless it should be noted that the high concentration of erbium doping used on this study (15%) is not the one which presents the most useful interest for applications as optical devices. Such a high concentration of erbium, selected for the XAS measurement, provides a clue to the chemical mechanisms which could explain the optical properties of the rare earth shown in former studies.

Infrared LEDs and microcavities based on erbium-doped silicon nanocomposites

Abstract: We demonstrate stable room-temperature electroluminescence at 154 μm under both forward and reverse bias conditions from erbium-doped silicon nanocomposites We also show enhanced and tunable emission from erbium when incorporated in porous silicon based microcavities Erbium is infiltrated in the pores by cathodic electrochemical migration of the ions followed by high temperature annealing (600–1100°C) to produce a composite material made of silicon nanocrystals and silicon dioxide The devices exhibit an exponential electroluminescence dependence in both bias conditions as a function of the driving current and driving voltage In reverse bias, the external quantum efficiency reaches 001% The devices show a large temperature dependence of the electroluminescence intensity The electroluminescence intensity decreases by a factor of 24 in reverse bias and 26 in forward bias when the temperature increases from 240 to 300 K The photoluminescence from the erbium-doped microcavity resonators is enhanced by more than one order of magnitude and tuned to emit in areas where the natural erbium emission is very weak

Excitation efficiency of electrons and holes in forward and reverse biased epitaxially grown Er-doped Si diodes

Abstract: In this letter, we report on the excitation efficiency of erbium ions by hot electrons and holes in Si:Er:O and Si1−yCy:Er pn diodes at 10 K. In forward bias, a higher electroluminescence efficiency at 1.54 μm is observed for incorporating the erbium ions in the p region of the diode, where enough holes are present to form bound excitons for erbium excitation. In reverse bias, electrons turn out to be 5000 times more efficient in impact exciting of Er3+ than holes at equal space-charge region widths. A dark region of 45 nm for electrons and about 70 nm for holes is present where no erbium excitation is possible. Impact excitation of Er codoped by C is much less efficient than for O codoping.