Growth, processing, and optical properties of epitaxial Er_2O_3 on silicon

Erbium-doped materials have been investigated for generating and amplifying light in low-power chip-scale optical networks on silicon, but several effects limit their performance in dense microphotonic applications. Stoichiometric ionic crystals are a potential alternative that achieve an Er^(3+) density 100× greater. We report the growth, processing, material characterization, and optical properties of single-crystal Er_2O_3 epitaxially grown on silicon. A peak Er^(3+) resonant absorption of 364 dB/cm at 1535nm with minimal background loss places a high limit on potential gain. Using high-quality microdisk resonators, we conduct thorough C/L-band radiative efficiency and lifetime measurements and observe strong upconverted luminescence near 550 and 670 nm

Silicon Nanoscale Materials : From Theoretical Simulations to Photonic Applications

Peer reviewe

The Selective Growth of Silicon Nanowires and Their Optical Activation

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Nonlinear optical properties of nano structures

Nonlinear optical properties of nanoscale semiconductors had been a topic of intense research in recent years in attempts to realize all-optical communication systems. These semiconductor nanoclusters, in the range of 1-100nm are hosted in a dielectric material and are considered as a particular example of Conditional Artificial Dielectric (CAD). It has been reported that the dielectric properties of such materials will be greatly changed by light intensity. Two main paths to realize nano semiconductor clusters are reported in this dissertation. The Pulsed Laser Deposition (PLD) technique is first described. Here we were investigating the effect of surface modification of nano silicon clusters by incorporating various gases (142, Ar, He) during the deposition process. Linear and nonlinear optical properties of these passivated Si nanoclusters were obtained. Ion Implantation is another successful method to obtain nano semiconductor clusters. In order to ftirther enhance the nonlinear optical properties of these clusters, we incorporated them in optically confining structures, such as three-dimensional photonic crystals. The latter part of the dissertation is devoted to three-dimensional periodic structures made of silica spheres (opal) which were implanted with Si, Ge and Er. Linear and nonlinear optical properties of these novel materials have been measured and assessed

Er3+-doped fluorotellurite thin film glasses with improved photoluminescence emission at 1.53 µm

7 págs.; 5 figs.; 4 tabs.Transparent oxyfluoride tellurite thin film glasses have been produced at room temperature by pulsed laser deposition in O2 atmosphere from an Er-doped TeO2–ZnO–ZnF2 bulk glass. Thin film glasses present high refractive index (n≥1.95) and good transparency (T≥80%) in the visible (λ>400 nm) and near infrared range. However, their photoluminescence (PL) performance at 1.5 μm is poor. Thermal annealing at moderate temperatures (T≤315 °C), well below glass crystallization, increases the PL intensity by more than one order of magnitude as well as the PL lifetime up to τ≈3.3 ms. Film glasses present a larger fraction of TeO3 trigonal pyramids than the bulk glass and a very large OH− content. The structure and composition of film glasses do not change upon annealing and thus the activation of the PL response is related to the improvement of the surface morphology and the significant decrease of their OH− content. & 2015ElsevierB.V.This work has been supported by the Spanish Government (Projects MAT2009-14282-C02-01, MAT2009-14282-C02-02, TEC 2012-38901-C02-01, MAT2013-48246-C2-2-P and FIS2013-48087-C2-1-P).Peer Reviewe

Optically active Er–Yb doped glass films prepared by pulsed laser deposition

3 pages, 2 figures.Active rare-earth Er3 + –Yb3 + co-doped phosphate glass films are produced in a single step by pulsed laser deposition. The films are multimode waveguides and exhibit the highest refractive index, optical density and 1.54 µm photoluminescence intensity and lifetime when deposited at low oxygen pressure (Pox4 (menor o igual) 10–5 Torr). The density of the films obtained under these conditions is higher than that of the target material as a consequence of the high kinetic energy of the species generated during ablation. Luminescent emission can be excited by optical pumping the Er3 + ions either directly or through cross-relaxation of the Yb3 + . Post-deposition annealing allows us to improve the luminescence performance.This work has been partially supported by CICYT (Spain) under Project No. TIC96-0467. One of the authors (J.M.B.) acknowledges financial support from the Spanish Ministry of Education.Peer reviewe

Fabrication and characterization of erbium-doped toroidal microcavity lasers

Erbium-doped SiO2 toroidal microcavity lasers are fabricated on a Si substrate using a combination of optical lithography, etching, Er ion implantation, and CO2 laser reflow. Erbium is either preimplanted in the SiO2 base material or postimplanted into a fully fabricated microtoroid. Three-dimensional infrared confocal photoluminescence spectroscopy imaging is used to determine the spatial distribution of optically active Er ions in the two types of microtoroids, and distinct differences are found. Microprobe Rutherford backscattering spectrometry indicates that no macroscopic Er diffusion occurs during the laser reflow for preimplanted microtoroids. From the measured Er doping profiles and calculated optical mode distributions the overlap factor between the Er distribution and mode profile is calculated: Gamma=0.066 and Gamma=0.02 for postimplanted and preimplanted microtoroids, respectively. Single and multimode lasing around 1.5 µm is observed for both types of microtoroids, with the lowest lasing threshold (4.5 µW) observed for the preimplanted microtoroids, which possess the smallest mode volume. When excited in the proper geometry, a clear mode spectrum is observed superimposed on the Er spontaneous emission spectrum. This result indicates the coupling of Er ions to cavity modes

Fabrication and characterisation of tellurite planar waveguides

Tellurite glasses, which contain Tellurium dioxide as the main component, have some remarkable optical properties which are well recognised and exploited in the bulk optics and fibre fields. They include a high acousto-optic figure of merit, wide mid infrared transparency, the highest optical nonlinearity amongst oxides, and excellent rare earth hosting, etc. Despite these attractive properties, until now, no one has succeeded in fabricating low loss planar waveguides in these materials. This work develops high quality optical planar waveguides in Tellurium dioxide for the first time. The project investigates the materials science for optical Tellurium dioxide films and discovers an appropriate waveguide fabrication method. The thin films have been fabricated by reactive radio frequency magnetron sputtering using a Tellurium target in an oxygen and argon atmosphere. Propagation losses at 1550nm in the planar films are 0.1dB/cm or lower in stoichiometric composition. The properties of films have been also found to be stable with thermal annealing up to 300 degree Celsius. Plasma etching of tellurite glasses has been systematically studied. High quality etching of Tellurium dioxide and chalcogenide glass films has been demonstrated with a Methane/Hydrogen/Argon gas mixture. As a result, a fabrication recipe which produces low loss (0.1dB/cm) planar waveguides has been discovered. The nonlinear coefficient of the sputtered TeO2 has been characterised by self-phase modulation (SPM) experiments and the second order nonlinear coefficient has been measured to be around 25 times that of silica. Significant signal conversion, -4dB, has achieved with large bandwidth of 30nm in the four-wave mixing (FWM) experiment pumped at 1550nm in a slightly normal dispersion waveguide. Erbium doped Tellurium oxide thin films have also been fabricated by co-sputtering of Erbium and Tellurium targets into an Oxygen and Argon atmosphere. The obtained films have been found to have good properties for Erbium doped waveguide amplifiers. The Erbium concentration can be controlled within the range of interest with Erbium/Tellurium ratios ranging from 0.1% to 3% or more. The 1.5 micrometre photoluminescence properties of the films are excellent with effective bandwidth of more that 60nm and intrinsic lifetime of order of 3ms. Despite the fact that there was OH contamination in the films, single mode Erbium doped waveguide amplifiers with high internal gain have been successfully obtained. The 1480nm pumped amplifier achieved internal gain from below 1520nm to beyond 1600nm. The peak gain of 2.8dB/cm and 40nm 3dB gain bandwidth have been accomplished. These results are a major stepping stone towards ""system-on-chip"" optical applications for telecom and mid infrared optics given the multifunctional nature of tellurite materials. -- provided by Candidate

Er Doped III-Nitride Semiconductors

Erbium ions (Er3+) doped in a solid material enables the intra 4f shell transitions from its first excited state (4I13/2) to the ground state (4I15/2). The intra-4f shell transition at 1540 nm is of exceptional interest as the wavelength matches the minimum loss region of silica fibers used in optical communications. Aluminium nitride (AlN) as host material for Erbium (Er) has attracted a lot of interest due to its physical and chemical properties such as the wide bandgap. Metal-Organic Chemical Vapor Deposition (MOCVD) is the most advanced state-of-art growth technique which provides both high quality single crystal thin film deposition capability and high growth rate. MOCVD is a versatile technique that widely used in research laboratories and in industrial factories. In this thesis, the effects of Er flux on MOCVD grown Er:AlN properties were investigated using different characterization techniques such as X-ray Diffraction (XRD), Photoluminescence (PL) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). XRD θ-2θ scans showed strong peak (002) for AlN and sapphire substrate (Al2O3), and the absence of any secondary phase for all samples. Rocking curve scans showed that increasing the Er flux increases the full width at half maximum (FWHM) of the symmetric (002) planes for AlN:Er. Surface imaging studies showed that increasing Er flux increases the surface roughness. SIMS profiles revealed that Er is uniformly distributed throughout the doped layers and enabled the direct measurement of the doped layer thickness using optical profiler. XPS exhibited the surface quantitative measurement of Aluminium, Nitrogen, Oxygen, and Carbon. PL measurements revealed that increasing the Er flux increases the 1.54μm emission intensity