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Related publications (319)

H-mode threshold power in TCV Ohmic plasmas

L-mode to H-mode (LH) transitions are observed in a large variety of plasma conditions in TCV Ohmic plasmas. The power flowing through the separatrix at the LH transition differs by up to a factor of two from the predicted H-mode threshold power. Variation ...

2002

Optimization of single-mode fiber coupling efficiency with an adaptive membrane mirror

René Dändliker

We propose and demonstrate the use of an adaptive membrane mirror to increase the efficiency of coupling light into optical single-mode fibers. The membrane mirror has an active area of 12 mm in diameter and is electrostatically activated by 37 electrodes. ...

2002

Reflection of waveguided X-rays in two-dimensional nanostructures

Christian David

The internal reflection of an excited X-ray waveguide mode in a synthetic nanostructure, defined by electron-beam lithography, has been measured. In this device, the X-ray beam is first coupled into a conventional vertical thin-film waveguide structure and ...

2002

Marginal beta-limit for neoclassical tearing modes in JET H-mode discharges

Olivier Sauter

A neoclassical tearing mode (NTM) requires a finite size seed island to become unstable. Usually the local pressure gradient is relatively large at the beta-values needed for these seed islands to destabilize the NTMs. Therefore, the island has a large gro ...

2002

Light-current characterization of dual-wavelength VCSELs

Jean-François Carlin, Marc Ilegems

The purpose of this paper is to present a detailed characterization of a dual-wavelength VCSEL - the BiVCSEL. This device consists of two active optical cavities, which share a coupling mirror and can be independently electrically pumped. We present the ou ...

SPIE2002

An ITER relevant evacuated waveguide transmission system for the JET-EP ECRH project

Timothy Goodman, Stefano Alberti, Minh Quang Tran, Jean-Philippe Hogge, Laurie Porte, Jean-Claude Magnin

An over-moded evacuated waveguide line was chosen for use in the transmission system for the proposed JET enhanced performance project (JET-EP) electron cyclotron resonance heating (ECRH) system. A comparison between the quasi-optical, atmospheric waveguid ...

2002

Phonon anomaly at the charge ordering transition in 1T-TaS2

Giorgio Margaritondo, László Forró, Richard Gaal, Helmuth Berger

The infrared reflectance of the transition-metal chalcogenide 1T-TaS2 has been measured at temperatures from 30 K to 360 K over 30-45 000 cm(-1) (4 meV-5.5 eV). The optical conductivity was obtained by Kramers-Kronig analysis. At 360 K only modest traces o ...

2002

How to tap an innocent waveguide

Olivier Martin

We study the interaction of a mode propagating in a planar waveguide with a three dimensional rectangular defect (protrusion or notch) in the structure. The scattering by the defect disturbes the propagation of the mode and light is coupled out of the wave ...

Optical Society of America2001

Broadband Superfluorescent Fiber Laser using Single-mode Doped Silica Fiber Combinations

René Dändliker

We demonstrate the possibility of broadening the emissions spectra of superfluorescent fiber lasers by combinations of different kinds of single-mode doped silica fibers. We obtained an optical bandwidth of more than 70 nm (FWHM) between 1030 and 1100 nm u ...

2000

Net coherent optical gain in strongly pumped semiconductor microcavities

Benoît Marie Joseph Deveaud, Ursula Oesterle, Cristiano Ciuti, Michele Saba

We study the subpicosecond gain dynamics in a high-finesse semiconductor microcavity containing quantum wells by means of degenerate pump-probe spectroscopy. Tuning the optical excitation in resonance with both the exciton and the cavity modes, at high pum ...

2000

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