Showing papers on "Erbium published in 2005"

Erbium in silicon

Abstract: The overlap of the principal luminescence band of the erbium ion with the low-loss optical transmission window of silica optical fibres, along with the drive for integration of photonics and silicon technology, has generated intense interest in doping silicon with erbium to produce a silicon-based optical source Silicon is a poor photonic material due to its very short non-radiative lifetime and indirect band gap, but it has been hoped that the incorporation of optically active erbium ions into silicon will permit the development of silicon-based light sources that will interface with both CMOS technology and optical fibre communications Some years into this activity, there have now been a wide range of experimental studies of material growth techniques, optical, physical and electrical properties, along with a considerable body of theoretical work dealing with the site of the erbium ion in silicon, along with activation and deactivation processes This paper reviews the current state of what remains an active field, summarizing results from a range of studies conducted over the last few years, and points to further developments by considering the prospects for successful photonic integration of erbium and silicon

Erbium-doped and Raman microlasers on a silicon chip fabricated by the sol–gel process

Abstract: We report high-Q sol–gel microresonators on silicon chips, fabricated directly from a sol–gel layer deposited onto a silicon substrate. Quality factors as high as 2.5×10^7 at 1561 nm were obtained in toroidal microcavities formed of silica sol–gel, which allowed Raman lasing at absorbed pump powers below 1 mW. Additionally, Er3+-doped microlasers were fabricated from Er3+-doped sol–gel layers with control of the laser dynamics possible by varying the erbium concentration of the starting sol–gel material. Continuous lasing with a threshold of 660 nW for erbium-doped microlaser was also obtained.

Resonantly pumped eyesafe erbium lasers

Abstract: The viability of high-power and high-energy, direct eyesafe emission from bulk erbium lasers has recently been demonstrated. In this paper, we present a review of eyesafe erbium lasers that are resonantly pumped by both fiber and diode lasers. High brightness pumping with a 1.53-/spl mu/m erbium fiber laser has yielded 60 W of continuous wave (CW) output, 10 W of repetitively Q-switched output, and as much as 16 mJ of pulse energy. Diode laser pumping has yielded 38 W of quasi-CW output and >40 mJ of Q-switched output.

A New Sol–Gel Material Doped with an Erbium Complex and Its Potential Optical‐Amplification Application

Abstract: The crystal structure of a ternary Er(DBM) 3 phen complex (DBM=dibenzoylmethane; phen=1,10-phenanthroline) and its in-situ synthesis via a sol-gel process are reported. The infrared (IR), diffuse reflectance (DR), and fluorescence spectra of the pure complex and the Er 3 + /DBM/phen co-doped luminescent hybrid gel, formed via an in-situ method (ErDP gel), have been investigated. The results reveal that the erbium complex is successfully synthesized in situ in the ErDP gel. Excitation at the maximum absorption wavelength of the ligands resulted in the typical near-IR luminescence (centered at around 1.54 μm) resulting from the 4 I 1 3 / 2 → 4 I 1 5 / 2 transition of the Er 3 + ion, which contributes to the efficient energy transfer from the ligands to the Er 3 + ion in both the Er(DBM) 3 phen complex and the ErDP gel (an antenna effect). The full width at half maximum (FWHM) centered at 1541 nm in the emission spectrum of the ErDP gel is 72 nm, which has potential for optical-amplification applications. Further theoretical analysis on the Er 3 + ion in the ErDP gel shows that it appears to be a promising candidate for tunable lasers and planar optical amplifiers.

Structure and properties of rare earth-doped lead borate glasses

Abstract: Influence of rare earth oxide (Nd2O3, Er2O3) addition on structure and glass properties has been investigated in PbO–B2O3–Al2O3–WO3 system. With an increasing of rare earth concentration, intensity of OH band drastically decreases and IR transparency is slightly shifted to the longer wavelengths. The ErBO3 crystalline phase has been identified basing on X-ray diffraction analysis. In opposite to the neodymium oxide, the erbium oxide plays the role as glass-modifier and influences on BO3 ↔ BO4 conversion, what was stated by infrared spectroscopy.

Switchable multiwavelength erbium-doped fiber ring laser with a multisection high-birefringence fiber loop mirror

Abstract: We proposed and demonstrated a new concept of switchable multiwavelength erbium-doped fiber ring laser with a multisection high-birefringence fiber loop mirror (HiBi-FLM). The HiBi-FLM results in the laser operating on different allowed wavelengths. The wavelength switching can be achieved by modifying the reflection spectrum of HiBi-FLM through two polarization controllers. The experiment demonstrates the switchable lasing operation within the random combination of three wavelengths, as well as with a large (/spl sim/40 dB) output signal to background noise ratio.

High-power tunable single-frequency single-mode erbium:ytterbium codoped large-core fiber master-oscillator power amplifier source

Abstract: We present a cladding-pumped single-frequency, single-mode erbium:ytterbium codoped fiber master-oscillator power amplifier source generating up to 151 W of continuous-wave output power at 1563 nm with 33% slope efficiency and 20 dB gain. This source was also tunable and had a stable operation range of 1546to1566 nm at an output power level in excess of 125 W. The doped fiber exploited a large-core design for improved power handling and mitigation of stimulated Brillouin scattering. There was no sign of having stimulated Brillouin scattering even at the highest power. Despite a large core (V=12), the output beam was nearly diffraction limited (M2=1.1). The source showed slight rollover at over 100 W of output power because of the onset of emission from ytterbium, centered at 1060 nm.

Widely tunable linear cavity multiwavelength Brillouin-Erbium fiber lasers.

Abstract: Wideband multiwavelength Brillouin-Erbium fiber laser (BEFL) utilizing a linear cavity is presented, highlighting the usage of higher Brillouin and lower erbium doped-fiber pump powers to achieve higher lasing spectral bandwidth. A tuning range of 60 nm has been obtained from 1525 to 1585 nm. The dependency of the Stokes signal tuning range on the laser’s pumping power is also elaborated. The wide tuning range of the proposed BEFL has potential in dense wavelength division multiplexing communication systems.

Self-stabilizing effect of four-wave mixing and its applications on multiwavelength erbium-doped fiber lasers

Abstract: Self-stabilizing effect of four-wave mixing (FWM) is analyzed and proven in this letter by using the undepleted approximation and the perturbation method. Multiwavelength erbium-doped fiber lasers with excellent stability and uniformity are demonstrated experimentally at room temperature. The novel fiber lasers are stabilized and equalized as a result of the balance between the self-stabilizing function of FWM and the mode competition effect of erbium-doped fiber.

Ultraslow light propagation in an inhomogeneously broadened rare-earth ion-doped crystal.

Abstract: We show that coherent population oscillations effect allows us to burn a narrow spectral hole (26 Hz) within the homogeneous absorption line of the optical transition of an erbium ion-doped crystal. The large dispersion of the index of refraction associated with this hole permits us to achieve a group velocity as low as 2.7 m/s with a transmission of 40%. We especially benefit from the inhomogeneous absorption broadening of the ions to tune both the transmission coefficient, from 40% to 90%, and the light group velocity from 2.7 m/s to 100 m/s.

Erbium-Doped Lithium Niobate Waveguide Lasers

Abstract: The recent progress in the field of Ti:Er:LiNbO 3 waveguide lasers with emission wavelengths in the range 1530 nm < λ < 1603 nm is reviewed. After a short discussion of the relevant fabrication methods concepts and properties of different types of lasers with grating resonator, acoustooptically tunable Fabry Perot type lasers and new ring laser structures are presented.

Absorption cross section and signal enhancement in Er-doped Si nanocluster rib-loaded waveguides

Abstract: Pump and probe experiments on Er3+ ions coupled to Si nanoclusters have been performed in rib-loaded waveguides to investigate optical amplification at 1.5μm. Rib-loaded waveguides were obtained by photolithographic and reactive ion etching of Er-doped silica layers containing Si nanoclusters grown by reactive sputtering. Insertion losses measurements in the infrared erbium absorption region allowed to gauge an Er3+ absorption cross section of about 5×10−21cm2 at 1534nm. Signal transmission under optical pumping at 1310nm shows confined carrier absorption of the Si nanoclusters. Amplification experiments at 1535nm evidence two pump power regimes: Losses due to confined carrier absorption in the Si nanoclusters at low pump powers and signal enhancement at high pump powers. For strong optical pumping, signal enhancement of about 1.2dB∕cm was obtained.

Raman spectroscopy studies of Er3+-doped zinc tellurite glasses

Abstract: Er3+-doped tellurite-based glasses have been investigated using Raman spectroscopy. The study is aimed to determine the structural characteristics of systems with broad Er3+ emission bands. In the Er2O3 concentration 0.5–4 mol% range studied, experimental results showed that adding erbium ions to zinc tellurite glass converts TeO4 trigonal bipyramid (tbp) units into TeO3 trigonal pyramid (tp) groups. A Raman band, associated with the Te–O–Te vibration mode has been observed near 450 cm−1. It was found that this band shows a significant decrease in intensity as the Er3+ ion concentration increases, indicating a structural disruption in the glass network due to the erbium increasing. On the other hand, the addition of erbium ions results in an increase in the Boson peak amplitude as compared to the respective undoped glasses which means that the contrast of the cohesive nanodomains relative to the softer interfacial zones increases. Further addition of more than 1 mol% of rare-earth ions, however, leads to a reduction of the Boson peak which is ascribed to clustering of dopants and/or a decrease in the contrast within the glass network.

Controlled erbium incorporation and photoluminescence of Er-doped Y2O3

Abstract: A high concentration of erbium doping was achieved in Y2O3 thin films on Si (100) by depositing Y2O3 alternatively with Er2O3 using radical-enhanced atomic layer deposition (ALD). Specifically, the erbium doping level was controlled by varying the ratio of Y2O3:Er2O3 cycles during deposition, and a 10:5 ratio yielded ∼9at.% erbium incorporation in Y2O3, confirmed by the compositional analysis using x-ray photoelectron spectroscopy. Room-temperature photoluminescence was observed in a 320-A Er-doped (9 at. %) Y2O3 film deposited at 350 °C. This result is very promising, since the film was fairly thin and no annealing at high temperature was needed to activate the erbium ions. This suggests that radical-enhanced ALD was able to preserve the optically active trivalent state of the erbium ion from its precursor state. The effective absorption cross section for Er3+ ions incorporated in Y2O3 was estimated to be on the order of 10−18cm2, about three orders of magnitude larger than the direct optical absorption ...

The structure of erbium doped sodium silicate glasses

Abstract: The structure of erbium doped sodium silicate glasses 1Er2O3–xNa2O–(99 − x)SiO2 (x = 0, 10, 20, 30) were studied by molecular dynamics simulations. The simulated glasses were compared with neutron diffraction and other experimental structural data. Silicon oxygen network ring size distributions and Qn distributions, the local structures around erbium ions, including the pair distribution functions, bond angle distributions, coordination number, dipole and quadrupole moments, were calculated. Their changes with sodium concentration were studied. It was found that both the Er–O bond length and the erbium coordination number increases from silica to sodium silicate glasses. Erbium ions adopt more favorable and uniform coordination environments in sodium silicate glasses. Erbium and sodium distribution and erbium clustering in the glasses were characterized. Erbium clustering is less obvious in sodium silicate glasses than in silica. Bond valences calculations of the simulated glasses provide a useful way to study the simulated glass structure. The comparison of bond valence of simulated glasses with related crystalline materials showed that the biggest difference be on the modifier sites.

87 nm bandwidth noise-like pulse generation from erbium-doped fibre laser

Abstract: Demonstrated is the operation of a passively modelocked erbium-doped fibre laser in noise-like mode and the generation of the pulse train with a bandwidth much wider than the gain bandwidth. Also demonstrated is super-continuum (SC) generation by launching the noise-like pulse into a highly nonlinear fibre and it is shown that the ultra-broadband SC spectra of over 960 nm is obtained by using the noise-like pulse instead of ultrashort pulses.

Silver-sensitized erbium-doped ion-exchanged sol–gel waveguides

Abstract: Ag- and Er-doped glass films have been synthesized with a combined sol–gel and ion-exchange route. The introduction of silver as erbium sensitizer in the film was obtained by ion exchanging Er-doped SiO2–Al2O3–Na2O sol–gel films. The films were subsequently annealed under controlled atmosphere to induce the migration and aggregation of the metal ions. Films showed different Er3+ photoluminescence behaviors depending on silver concentration and aggregation state. The interaction between erbium ions and Ag centers has been investigated and enhancement of the excitation cross section due to the silver sensitizing effect has been demonstrated. The developed synthesis also allowed the realization of erbium-doped channel waveguides by a selective Na–Ag ion-exchange process .

Chalcogenide-Bound Erbium Complexes: Paradigm Molecules for Infrared Fluorescence Emission

Abstract: The near-infrared luminescence properties of the nanoscale erbium ceramic cluster (THF)14Er10S6Se12I6 (Er10, where THF = tetrahydrofuran) and the molecular erbium thiolate (DME)2Er(SC6F5)3 (Er1, where DME = 1,2-dimethoxyethane) were studied by optical absorption, photoluminescence, and vibrational spectroscopy. The calculated radiative decay time of 4 ms for the 4I13/2 → 4I15/2 transition is comparable to the reported values for previously reported organic complexes. The recorded emission spectrum of the 4I13/2 → 4I15/2 transition was centered at 1544 nm with a bandwidth of 61 and 104 nm for Er10 and Er1, respectively, with stimulated emission cross sections of 1.3 × 10-20 cm2 (Er10) and 0.8 × 10-20 cm2 (Er1) that are comparable to those of solid-state inorganic systems. Lifetime measurements of the 1544 nm decay showed a fluorescence decay time of the order of 3 ms for Er10 that, together with the radiative decay time, yielded a quantum efficiency above 78%, which is considered to be the highest reported...

S-band Brillouin erbium fibre laser

Abstract: A multi-wavelength Brillouin erbium fibre laser, which operates in short wavelength band (S-band), is proposed and demonstrated. The system employs both linear gain and nonlinear gain from a 20 m S-band erbium-doped fibre and a 500 m singlemode fibre, respectively, to generate an optical wavelength comb with spacing of approximately 0.084 nm. Two 80/20 couplers were used in the system as an internal feedback of generated Stokes signal to produce cascaded Brillouin Stokes for multiwavelength operation. A stable output laser comb of up to seven lines was obtained with a Brillouin pump of 3.5 mW and a 980 nm pump of 200 mW.

Enhanced 1.54μm photoluminescence from Er-containing ZnO through nitrogen doping

Abstract: Nitrogen doping into an erbium (Er)-containing ZnO specimen through the N+ irradiation and the subsequent annealing in air was found to increase the photoluminescence (PL) intensity around 1.54μm by about 40 times. The existence of nitrogen in the specimen was proved firmly by means of the N14(d,α)C12 nuclear reaction analysis. Further, the Ne+ irradiation was conducted instead of the N+ irradiation, but no effect was observed in the PL spectra. So, it was concluded that the substitution of N for O could modify the local structure around Er3+, resulting in the surprisingly large enhancement of the PL intensity.

Nucleation efficiency of erbium and ytterbium fluorides in transparent oxyfluoride glass-ceramics

Abstract: Oxyfluoride glasses (GeO2–PbO–PbF2) doped with erbium and/or ytterbium fluorides were prepared. Highly transparent glass-ceramics, containing s–PbF2 nanocrystallites, were successfully obtained by controlled glass devitrification and were studied as they could lead to promising optical applications. To characterize the samples, differential thermal analysis, x-ray diffraction, and transmission electron microscopy were performed, revealing a variation of the crystallites size, the crystallites number and s–PbF2 crystallization temperature according to the doping ion. Indeed, the analyses indicated differences between erbium and ytterbium fluorides in promoting the crystallization of the fluoride phase. Although both fluorides act as seeds for s–PbF2 heterogeneous nucleation, erbium fluoride has higher nucleation efficiency than ytterbium fluoride and runs the nucleation process in co-doped samples. Energy dispersive x-ray microanalysis insured high rare-earth segregation into the crystallites, proving the formation of a solid solution Pb1-x-yErxYbyF2 +x+y, also confirmed by the unit cell parameter study.

Laser cooling transitions in atomic erbium.

Abstract: We discuss laser cooling opportunities in atomic erbium, identifying five J→J+1 transitions from the 4f126s2 3H6 ground state that are accessible to common visible and near-infrared continuous-wave tunable lasers. We present lifetime measurements for the 4f11(4Io15/2)5d5/26s2 (15/2, 5/2)7 o state at 11888 cm−1 and the 4f11(4Io 13/2)5d3/26s2 (13/2, 5/2)7o state at 15847 cm−1, showing values of 20±4 µs and 5.6±1.4 µs, respectively. We also present a calculated value of 13±7 s−1 for the transition rate from the 4f11(4Io 15/2)5d3/26s2 (15/2, 3/2)7 o state at 7697 cm-1 to the ground state, based on scaled Hartree-Fock energy parameters. Laser cooling on these transitions in combination with a strong, fast (5.8 ns) laser cooling transition at 401 nm, suggest new opportunities for narrowband laser cooling of a large-magnetic moment atom, with possible applications in quantum information processing, high-precision atomic clocks, quantum degenerate gases, and deterministic single-atom doping of materials.

Experimentally verified modeling of erbium-ytterbium co-doped DFB fiber lasers

Abstract: For the first time, the simulation results of fiber distributed feedback (DFB) lasers are compared against experimental data in this paper. The pump source, active medium, and grating are all modeled and simulated to predict actual laser characteristics. Simple characterization methods are illustrated for the measurement of model parameters. Large loss at the pump wavelength is observed, attributed to the lifetime quenching of Yb ions, and included in the model as a critical parameter. DFB lasers with two different apodization profiles successfully simulated with the same set of model parameters.

Dynamics of high-power erbium–ytterbium fiber amplifiers

Abstract: Dynamic regimes of high-peak-power erbium–ytterbium (Er3+–Yb3+) codoped fiber amplifiers are analyzed for nanosecond-to-microsecond pulses. High-energy pulse generation requires a large-core fiber amplifier to increase energy storage and the threshold of nonlinear effects. A numerical model of large-core Er3+–Yb3+ fiber amplifiers is described. Dynamics of peak powers, amplified spontaneous emission, and population inversion are presented. Influence of radial dependence and reflections at the extremities are studied. Modeling and experimental results are compared for simple-pass and double-pass amplifier configurations. The role of parasitic reflections is highlighted. A semianalytical model is derived for low and high repetition rates.

Fabrication of yttrium oxide and erbium oxide coatings by PVD methods

Abstract: The development of insulating coatings is one of the most important subjects in fusion reactor liquid lithium blanket research and development. The compounds aluminum nitride, yttrium oxide and erbium oxide are considered to be candidate materials for ceramic coatings because of their high electrical resistance and their high compatibility with liquid lithium. In the present study, two types of PVD methods were employed for fabrication of coatings, and their properties were examined. Yttrium oxide and erbium oxide coatings were fabricated by means of radio frequency (RF) sputtering, and erbium oxide coatings were fabricated by arc source plasma assisted deposition. The coatings were all close to their stoichimetric composition, and had higher resistances than that required in the fusion reactor (102–104 Ωm). The coatings had the crystallinity observed by X-ray diffraction (XRD), which were influenced by fabrication parameters as high frequency electric power or substrate temperature. Annealing after fabrication makes coatings crystallized more while the crystallinity of the coatings fabricated at low temperature were inferior to that of the coatings fabricated at higher temperature.

Erbium-doped hole-assisted optical fiber amplifier: design and optimization

Abstract: An erbium-doped hole-assisted optical fiber amplifier, to be employed in the third band of the optical communications, is designed and optimized via a tailor made computer code. The finite element method is used for the electromagnetic investigation of the microstructured fiber section. The simulation model takes into account all the rare earth physical phenomena, i.e., the pump and signal propagation, the amplified spontaneous emission, the secondary transitions pertaining to the ion-ion interactions, and so on. The device feasibility is tested via a number of simulations, realistically performed by taking into account the actual parameters pertaining to the dispersion of the germania/silica glass, the erbium emission and absorption cross sections, the propagation losses. By simulation, in the small signal operation, a gain close to 42.8 dB is demonstrated for a fiber 13-m long, using a pump power of 50 mW at the signal wavelength /spl lambda//sub s/=1536 nm, the pump and the signal being copropagating.

Nearly quantum noise limited timing jitter from miniature Er:Yb:glass lasers

Abstract: We have measured the relative timing jitter of two passively mode-locked 10-GHz Er:Yb:glass lasers to be 190 fs (100 Hz-1.56 MHz) in free-running and 26 fs (6 Hz-1.56 MHz) in synchronized operation.