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Showing papers by "Kerstin Worhoff published in 2008"


Proceedings Article
27 Nov 2008
TL;DR: Investigation of the effects of parameters such as ion beam current, dwell time, scanning strategy, and dielectric charging effects are addressed and excellent quality gratings with smooth and uniform sidewalls are reported.
Abstract: We report on utilization and optimization of the focused ion beam technique for fabrication of nano-structures on $Al_2O_3$ channel waveguides for applications in integrated photonic devices. In particular, investigation of the effects of parameters such as ion beam current, dwell time, scanning strategy, and dielectric charging effects are addressed. As a result of optimization of these parameters, excellent quality gratings with smooth and uniform sidewalls are reported. The effects of Ga ion implantation during the milling process on the optical performance of the devices are discussed.

3 citations


Proceedings Article
27 Nov 2008
TL;DR: Clemmen et al. as discussed by the authors presented a survey of the state-of-the-art technologies in the field of Information Quantification and Information Processing at the Universite Libre de Bruxelles.
Abstract: S. Clemmen1, Kien Phan Huy2, Wim Bogaerts3, Roel G. Baets3, Philippe Emplit4, and Serge Massar1 1 Laboratoire d’Information Quantique, CP 225, Universite Libre de Bruxelles (U.L.B.), boulevard du Triomphe, 1050 Brussels, Belgium 2 Departement D’Optique P.M. Duffieux, Institut FEMTO-ST, Centre National de la Recherche Scientifique UMR 6174, Universite de Franche-Comte, 25030 Besancon, France 3 Department of Information Technology (INTEC), Ghent University IMEC, Sint-Pietersnieuwstraat 41, 9000 Gent, BELGIUM 4 Service OPERA-Photonique, CP 194/5, Universite Libre de Bruxelles (U.L.B.), avenue F.D. Roosevelt 50, 1050 Brussels, Belgium

2 citations


01 Jul 2008
TL;DR: In this article, a channel waveguides were fabricated by reactive ion etching with propagation losses down to 0.21 dB/cm, resulting in 5.4 dB net gain over a waveguide length of 6.4 cm.
Abstract: Erbium-doped aluminum oxide (Al2O3:Er) is a promising material for integrated amplifier or tunable laser applications due to its wide gain spectrum around 1550 nm. We deposited Al2O3 layers on thermally oxidized Si-wafers by reactive co-sputtering at 550°C. Propagation losses were 0.11 dB/cm at λ =1.5 μm. Channel waveguides were fabricated by reactive ion etching with propagation losses down to 0.21 dB/cm. Under pumping at 977 nm, the optical small-signal gain at 1533 nm is 0.84 dB/cm, resulting in 5.4 dB net gain over the waveguide length of 6.4 cm. Net gain is obtained over a wavelength range of 41 nm. The Er concentration was measured using Rutherford Back-Scattering (RBS). Lifetimes of the 4I13/2 level of up to 7 ms were measured for Er concentrations around 2×1020 cm-3. A faster decay with an increasingly non-exponential initial component is measured for higher Er concentrations (Fig. 2). While the initial quenching is probably due to migration-accelerated energy-transfer upconversion between neighboring Er3+ ions in the 4I13/2 level, the decreasing exponential tail is due to either pair-induced energy-transfer upconversion or quenching by impurity ions. Detailed investigations of the quenching mechanisms are currently under way.

1 citations


Proceedings Article
30 Aug 2008
TL;DR: In this paper, a channel waveguide laser has been demonstrated by toploading of a planar waveguide with a piece of standard optical fibre in combination with contact fluid, with a threshold of 85mW and a slope efficiency of 30%.
Abstract: A channel waveguide laser has been demonstrated by top-loading of a $KY(WO_4)_2:Yb^{3+}$ planar waveguide with a piece of standard optical fibre in combination with contact fluid. Laser emission with a threshold of 85mW and a slope efficiency of 30% has been obtained.

Proceedings Article
27 Nov 2008
TL;DR: In this paper, a silicon nitride-based waveguide device is presented for the detection of light backscattered from liquids, which is composed of a source waveguide and a series of collector waveguides displaced relatively to the source.
Abstract: A silicon nitride based waveguide device is presented for the detection of light backscattered from liquids. The device is composed of a source waveguide and a series of collector waveguides displaced relatively to the source. The experimental result shows that detection of photons backscattered from the interior of a droplet in direct surface contact with source and detector waveguides is feasible, although the amount of light captured by the latter is extremely small. The intensity of the backscattered light measured from each of the collector waveguides is found to be in good agreement with simulation results based on a Monte-Carlo approach.

27 Nov 2008
TL;DR: In this article, the excitation and relaxation processes relevant for establishing optical gain in Al2O3:Er3+ on the 4I13/2 -> 4I15/2 transition at 1.5 µm are investigated.
Abstract: The excitation and relaxation processes relevant for establishing optical gain in Al2O3:Er3+ on the 4I13/2 -> 4I15/2 transition at 1.5 µm are investigated. Excited-state absorption in the wavelength range from 900-1800 nm is measured in a pump-probe experiment. The 4I13/2 and 4I11/2 lifetimes are measured after direct excitation and the macroscopic parameter of the energy-transfer-upconversion (ETU) process (4I13/2, 4I13/2) -> (4I15/2, 4I9/2) is determined independently from both decay curves. By use of the Zubenko model the microscopic parameters of ETU and energy migration are derived. It is found that above the Er3+ concentration at which the transition from static to migration-accelerated ETU takes place also the 1.5-µm amplifier gain is diminished by this process.

Proceedings Article
30 May 2008
TL;DR: In this article, reactive co-sputtering has been applied as a low-cost method for deposition of Er3+-doped $Al 2O_3:Er^{3+}$ layers.
Abstract: Reactive co-sputtering has been applied as a low-cost method for deposition of $Al_2O_3:Er^{3+}$ layers. Channel waveguide fabrication has been optimized and results in waveguides with low background losses (0.21 dB/cm), demonstrating the feasibility of realizing active photonic devices. A net optical gain of 0.84 dB/cm for a 1533-nm signal has been obtained in a 700-nm-thick Er3+-doped $Al_2O_3$ waveguide pumped at 980 nm, which is the highest gain demonstrated thus far in this material.