Showing papers on "Erbium published in 2003"

Fiber-coupled erbium microlasers on a chip

Abstract: An erbium-doped, toroid-shaped microlaser fabricated on a silicon chip is described and characterized. Erbium-doped sol-gel films are applied to the surface of a silica toroidal microresonator to create the microcavity lasers. Highly confined whispering gallery modes make possible single-mode and ultralow threshold microlasers.

1.5-microm monolithic GaInNAs semiconductor saturable-absorber mode locking of an erbium fiber laser.

Abstract: We present a new monolithic GaAs-based semiconductor saturable bsorber operating at 1.55 µm. An epitaxially grown absorber mirror in a GaInNAs/GaAs material system was successfully used to mode lock an erbium-doped fiber laser. The GaInNAs material system possesses intriguing physical properties and provides great potential for lasers and nonlinear optical devices operating at the 1.3–1.55‐µm wavelength range.

High efficiency light emitting devices in silicon

Abstract: We report on the fabrication and performances of highly efficient Si-based light sources. The devices consist of MOS structures with erbium (Er) implanted in the thin gate oxide. They exhibit strong 1.54 μm electro-luminescence (EL) at 300 K with a 10% external quantum efficiency, comparable to that of standard light emitting diodes using III–V semiconductors. Emission at different wavelengths has been achieved incorporating different rare earths (terbium (Tb) and ytterbium (Yb)) in the gate dielectric. The external quantum efficiency depends on the rare-earth ions incorporated and ranges from 10% (for a Tb doped MOS) to 0.1% (for an Yb doped MOS). RE excitation is caused by hot electrons impact and oxide wearout limits the reliability of the devices. Much more stable light emitting MOS devices have been fabricated using Er-doped silicon rich oxide (SRO) films as gate dielectric. These devices show a high stability, with an external quantum efficiency reduced to 0.2%. In these devices, Er pumping occurs partially by hot electrons and partially by energy transfer from the Si nanostructures to the rare-earth ions, depending on Si excess in the film. Si/SiO 2 Fabry–Perot microcavities have been fabricated to enhance the external quantum emission along the cavity axis and the spectral purity of emission from the films that are used as active media to fabricate a Si-based resonant cavity light emitting diode (RCLED). These structures are fabricated by chemical vapour deposition on a silicon substrate. The microcavities are tuned at different wavelengths (nm): 540, 980 and 1540 (characteristic emission wavelengths, respectively, for Tb, Yb and Er). The reflectivity of the microcavities is about 97% and the quality factor ranges from 60 (for the cavity tuned at 980 nm) to 95 (for the cavities tuned at 540 and 1540 nm).

Characterization of new erbium-doped tellurite glasses and fibers

Abstract: Tellurite glasses are promising candidates for optical fiber laser and amplifier applications because of their excellent optical and chemical properties. The emission spectrum from erbium in tellurite glasses is almost twice as broad as the corresponding spectrum in silica. In this presentation, we report the results of a two-prong investigation of new tellurite glasses: a Raman study that provides detail information on the microscopic structure of these glasses, and a study of the erbium emission in fibers fabricated from these glasses. Specifically, we report on the emission from fibers of different lengths and for different pumping schemes.

Cooperative upconversion as the gain-limiting factor in Er doped miniature Al2O3 optical waveguide amplifiers

Abstract: Erbium doped Al2O3 waveguide amplifiers were fabricated using two different doping methods, namely Er ion implantation into sputter deposited Al2O3, and co-sputtering from an Er2O3/Al2O3 target. Although the Er concentration in both materials is almost identical (0.28 and 0.31 at. %), the amplifiers show a completely different behavior. Upon pumping with 1.48 μm, the co-sputtered waveguide shows a strong green luminescence from the 4S3/2 level, indicating efficient cooperative upconversion in this material. This is confirmed by pump power dependent measurements of the optical transmission at 1.53 μm and the spontaneous emission at 1.53 and 0.98 μm. All measurements can be accurately modeled using a set of rate equations that include first order and second order cooperative upconversion. The first order cooperative upconversion coefficient C24 is found to be 3.5×10−16 cm3 s−1 in the co-sputtered material, two orders of magnitude higher than the value obtained in Er implanted Al2O3 of 4.1×10−18 cm3 s−1. It ...

Effect of Bi 2 O 3 on the spectroscopic properties of erbium-doped bismuth silicate glasses

Abstract: The spectroscopic properties of erbium-doped silicon dioxide, bismuth oxide, and sodium oxide glasses are investigated based on Judd–Ofelt analysis for absorption spectra, bandwidth analysis for emission spectra, and lifetime measurements of the 4I13/2 level of Er3+. The effects of bismuth oxide on these three optical parameters are discussed in terms of the local basic nature of the glass, of variations in ligand fields about Er3+ sites, and of the phonon energy and the refractive index of the glass host, respectively. The data obtained suggest that bismuth oxide does not have a promising composition for use with a broadband erbium-doped fiber amplifier.

Integrated optical distributed feedback laser with Ti:Fe:Er:LiNbO3 waveguide

Abstract: A distributed feedback (DFB) laser in LiNbO3 is demonstrated using a Ti:Fe:Er:LiNbO3 waveguide with a holographically written photorefractive grating. The DFB laser was combined with a waveguide amplifier on the same substrate. Up to 1.12 mW of output power at λ=1531.35 nm was emitted by the laser/amplifier combination at a pump power level of 240 mW (λP=1480 nm). The emission spectrum consists of the two lowest-order DFB modes of about 3.9 GHz frequency spacing. Whereas the measured threshold gain of ∼3.3 dB/cm approximately agreed with the modeling results, the observed mode spacing was clearly smaller than calculated.

A tunable S-band erbium-doped fiber ring laser

Abstract: In this paper, we experimentally investigate and demonstrate an S-band erbium-doped fiber (EDF) ring laser based on an erbium-doped silica fiber and 980-nm pumping laser. Widely tunable range from 1480 to 1522 nm, and the sidemode suppression ratio (SMSR) of >30 dB/0.1 nm and the output power of >-2 dBm in the operating range from 1482 nm to 1517 nm have been achieved for this ring laser. Under the constant power control, the output power variation less than /spl plusmn/0.05 dB can also be accomplished over the tuning range from 1482 to 1517 nm. This S-band EDF ring laser is promising for the future S-band applications.

Erbium-doped Si nanocrystals: optical properties and electroluminescent devices

Abstract: In the last decade, a strong effort has been devoted towards the achievement of efficient light emission from silicon. Among the different approaches, rare-earth doping and quantum confinement in Si nanostructures have shown great potentialities. In the present work, the synthesis and properties of low-dimensional silicon structures in SiO 2 will be analyzed. All of these structures present a strong room temperature optical emission, tunable in the visible by changing the crystal size. Moreover, Si nanocrystals (nc) embedded in SiO 2 together with Er ions show a strong coupling with the rare earth. Indeed each Si nc absorbs energy which is then preferentially transferred to the nearby Er ions. The signature of this interaction is the strong increase of the excitation cross section for an Er ion in the presence of Si nc with respect to a pure oxide host. We will show the properties of Er-doped Si nc embedded within Si/SiO 2 Fabry–Perot microcavities. Very narrow, intense and highly directional luminescence peaks can be obtained. Moreover, the electroluminescence (EL) properties of Si nc and Er-doped Si nc in MOS devices are investigated. It is shown that an efficient carrier injection at low voltages and quite intense room temperature EL signals can be achieved, due to the sensitizing action of Si nc for the rare earth. These data will be presented and the impact on future applications discussed.

Active waveguide devices by Ag–Na ion exchange on erbium–ytterbium doped phosphate glasses

Abstract: Arrays of buried channel waveguide lasers and amplifiers were fabricated by silver–sodium ion exchange in erbium–ytterbium doped phosphate glass substrates. The fabrication process, consisting of a thermal diffusion from fused salt followed by a field-assisted burial step, is optimized to get single-mode channel arrays fully compatible with standard single-mode fibres and fibre ribbon cables. The active channels were successfully tested realizing both lasers and amplifiers in the C-band suitable for optical communications. Erbium waveguide lasers exhibit a maximum output power of ∼1.7 mW and erbium-doped waveguide amplifiers provide a maximum internal gain of ∼11.3 dB at 1534 nm.

Halogen substitution as an efficient tool to increase the near-infrared photoluminescence intensity of erbium(III) quinolinates in non-deuterated DMSO

Abstract: Substitution of the hydrogen atoms in the 5- and 7-positions of the quinoline moiety by halogen atoms (Cl and Br) increases the near-infrared (NIR) photoluminescence intensity of the trivalent erbium ion by 30%.

New Fluoride Glasses for Laser Applications

Abstract: A new fluoride glass composition revealing a high stability, with a weak nucleation tendency, has been studied. The erbium spectroscopic properties have been investigated in these glasses in order to determine the parameters relevant to the 3 μm 4I11/2 → 4I13/2 laser transition. A Judd–Ofelt analysis was performed to obtain radiative lifetimes and emission cross-sections. Lifetime measurements have also been performed to optimize Er3+ concentration, taking into account the self-terminating behavior of the 3 μm laser transition. Also, Er:ZBLALiP microsphere 1550 nm lasers have been made with pumping by a half fiber taper at 1480 nm.

Indirect excitation of Er3+ in sol-gel hybrid films doped with an erbium complex

Abstract: Transparent sol-gel hybrid films doped with erbium tris 8-hydroxyquinoline were prepared using methyltriethoxysilane, vinyltriethoxysilane, and phenyltrimethoxysilane as precursors. We obtain a strong 1.53-μm Er3+ luminescence with a wide full width at half-maximum and no thermal quenching. Comparison of absorption of the film with the pump wavelength dependence of Er3+ luminescence intensity indicates the presence of an efficient indirect excitation path for Er3+ via organic ligands.

Erbium-doped fiber laser simultaneously mode locked on more than 24 wavelengths at room temperature

Abstract: We demonstrate simultaneous mode locking of more than 24 wavelengths at 3 GHz in an actively mode-locked erbium-doped fiber laser operating at room temperature. The multiwavelength operation is achieved when a frequency shifter and an all-fiber 50-GHz periodic filter are inserted into a ring cavity. Active mode locking is performed with an amplitude modulator, and pulses with a FWHM of 30 ps are obtained.

Modified spontaneous emission from erbium-doped photonic layer-by-layer crystals

Abstract: The spontaneous emission from luminescent Si photonic layer-by-layer crystals is studied. Luminescence from both implanted Er ions and the polycrystalline Si host is observed in the 1.1-1.7 μm wavelength range and serves as a probe of the photonic band structure. The spontaneous emission is strongly suppressed for wavelengths between 1.4 and 1.7 μm. The spectral changes are described by a model that takes into account changes in the local density of states, internal Bragg scattering in the crystal, and the internal quantum efficiency of the optical transition involved. A spectral attenuation of ∼5 dB per unit cell is derived from the spontaneous emission data, consistent with theory and transmission data.

Analysis of heat generation and thermal lensing in erbium 3-/spl mu/m lasers

Abstract: The influence of energy-transfer upconversion (ETU) between neighboring ions in the upper and lower laser levels of erbium 3-/spl mu/m continuous-wave lasers on heat generation and thermal lensing is investigated. It is shown that the multiphonon relaxations following each ETU process generate significant heat dissipation in the crystal. This undesired effect is an unavoidable consequence of the efficient energy recycling by ETU in erbium 3-/spl mu/m crystal lasers, but is further enhanced under nonlasing conditions. Similar mechanisms may affect future erbium 3-/spl mu/m fiber lasers. In a three-dimensional finite-element calculation, excitation densities, upconversion rates, heat generation, temperature profiles, and thermal lensing are calculated for a LiYF/sub 4/:Er/sup 3+/ 3-/spl mu/m laser. In the chosen example, the fraction of the absorbed pump power converted to heat is 40% under lasing and 72% under nonlasing conditions. The heat generation in a LiYF/sub 4/:Er/sup 3+/ 3-/spl mu/m laser is 1.7 and the thermal-lens power up to 2.2 times larger than in a LiYF/sub 4/:Nd/sup 3+/ 1-/spl mu/m laser under equivalent pump conditions, thus, also putting a higher risk of rod fracture on the erbium system.

Tunable L -band erbium-doped fibre ring laser by means of induced cavity loss using a fibre taper

Abstract: In this paper, we present a continuous-wave tunable fibre ring laser operating in the L-band. A bi-directional pumped L-band erbium-doped fibre amplifier provides gain to the loop. Tunability is achieved by bending a single-mode fibre taper using a micrometer drive, controlling in this way the spectral cavity losses. Laser emission is achieved between 1587 and 1606 nm, and low variation of the output laser power is observed over all the tuning range.

Single-mode tapered waveguide laser in Er-doped glass with multimode-diode pumping

Abstract: We report on a demonstration of a planar waveguide laser configuration for single-mode operation around 1550 nm using cost-effective multimode diode pumping. The laser was fabricated by Ag film ion exchange in a hybrid phosphate glass which has active and passive regions monolithically integrated in a single glass chip. Power of 54 mW at 1538 nm was measured from the single-mode output waveguide.

Erbium-doped phosphate-glass tunable single-mode fiber laser using a tunable fabry-perot filter

Abstract: A short laser cavity (up to 30 cm in length) comprising a free-space tunable MEMS Fabry-Perot filter, a collimating lens and a section of erbium-doped phosphate gain fiber (2-25 cm) is formed between a pair of broadband reflectors. The cavity is optically pumped to excite the erbium ions and provide gain, which establishes an initial longitudinal mode structure that spans the C-band with a mode spacing of at least 0.3 GHz and a roundtrip unsaturated gain of at least 8 dB over the tuning range. A controller tunes the MEMS filter, which has a filter function whose spectral width is at most ten and preferably less than four times the longitudinal mode spacing, to align its transmission maxima to one of a plurality of discrete output wavelengths that span the C-band. A thermal control element adjusts the longitudinal mode structure to align a single mode with the transmission maxima of the filter. Because the spectral width of the filter function is narrow, laser emission will be limited to a single longitudinal mode.

Nucleation and anionic environment of Er3+ in a germanate glass

Abstract: The nucleation of PbF 2 crystallites has been investigated in a germanate glass (GeO 2 –PbO–PbF 2 ) doped with different erbium oxide and halides: Er 2 O 3 , ErF 3 , ErOF and ErCl 3 . Differential thermal analysis has been conducted on a unique glass composition doped with a variable content of these four erbium compounds. A memory of the initial coordination sphere, anionic neighbouring, of the erbium ions before melting of the powders has been observed in the as melted glasses through the variation of their thermal analysis curves and through their nucleation tendency obtained after thermal treatments.

Rare-earth doped phosphate-glass single-mode fiber lasers

Abstract: A compact low-cost continuous single-mode fiber laser delivers output powers in excess of 50 mW over the C-band (1530 nm- 1565 nm). The phosphate glass fiber supports the high doping concentrations of erbium and ytterbium (Er:Yb) without self-pulsation that are required to provide sufficient gain per centimeter needed to achieve high power in the ultra short cavity lengths necessary to support single-mode lasers. The use of fiber drawing technology provides a lower cost solution than either combined solution doping/MCVD fiber fabrication or waveguide fabrication. The ability to multi-mode clad pump the fiber further reduces cost, which is critical to the successful deployment of fiber lasers in the burgeoning metro markets.

Optical amplification at 1534 nm in erbium-doped zirconia waveguides

Abstract: We have developed planar waveguides with net gain in erbium-doped zirconia. Ion-beam sputtering was used to deposit amorphous high-refractive-index zirconia films, which were fabricated into single-mode waveguides. By adjusting oxygen flow rates while sputtering, and annealing the films after deposition, waveguide losses were reduced to 0.45 dB/cm at 1534 nm. Erbium in the zirconia, added by co-sputtering, had a wide, 54-nm full-width at half maximum emission band centered at 1538 nm, which offers potential advantages for wideband amplification in wavelength division multiplexing systems. When pumped with 36 mW at 980 nm, a 6.5 cm long, 8.8 /spl times/ 10/sup 19/ cm/sup -3/ doped waveguide produced 2.95 dB of optical amplification at 1534 nm. This was enough to overcome the waveguide loss and produce a small amount of net gain. With a higher pump power, substantial net gain appeared to be possible. These results show that wide-bandwidth erbium-doped optical amplifiers should be possible in zirconia.

Sol-gel silica-on-silicon buried-channel EDWAs

Abstract: Silica-on-silicon erbium-doped waveguide amplifiers (EDWAs) fabricated by the sol-gel route are demonstrated. The preparation of stable sols is first described, with emphasis on identifying chemical routes that allow the incorporation of sufficient concentration of erbium without precipitation or gelation. Erbium-doped glasses containing various codopants, such as phosphorus, aluminum, germanium and ytterbium are formed and used in the construction of buried channel guide EDWAs. A range of optical measurements is presented, and the effects of the dopants in eliminating erbium ion quenching and improving pumping efficiency are evaluated. The best material system-Er/Yb codoped aluminophosphosilicate glass-has low background loss and a net gain of 1.1 dB/cm.

Spectroscopic studies of erbium-doped potassium-lead double chloride crystals KPb2Cl5:Er3+. 1: Optical spectra and relaxation of excited states of the erbium ion in potassium-lead double chloride crystals

Abstract: Optical spectra, intensities of radiative and nonradiative transitions, and luminescence kinetics in erbium-doped potassium-lead double chloride crystals KPb2Cl5:Er3+s(KPC:Er3+) were investigated. The crystals were grown by the Bridgman-Stockbarger method. Their absorption and luminescence spectra were studied experimentally. The crystal-matrix absorption edge was determined at 80 and 300 K. Intensity parameters, radiative transition probabilities, branching ratios, and nonradiative relaxation rates were estimated by the Judd-Ofelt method. The luminescence kinetics from the emitting levels 4 G 11/2, 2 G 9/2, 4 S 3/2, and 4 F 9/2 upon selective excitation was studied.