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Hofstetter, Daniel

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Hofstetter, Daniel
Affiliation principale
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Ancien.ne collaborateur.trice
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https://libra.unine.ch/handle/123456789/472

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  • Publication
    Métadonnées seulement
    Continuous-wave operation of quantum cascade laser emitting near 5.6
    (2003)
    Yarekha, Dmitri A
    ;
    Beck, Mattias
    ;
    Blaser, Stéphane
    ;
    Aellen, Thierry
    ;
    Gini, Emilio
    ;
    Hofstetter, Daniel 
    ;
    Faist, Jérôme
    Buried heterostructure quantum cascade lasers emitting at 5.64 mum are presented. Continuous-wave (CW) operation has been achieved at -30degreesC for junction down mounted devices with both facets coated. A 750 mum-long laser exhibited 3 mW of CW power with a threshold current density of 5.4 kA/cm(2).
  • Publication
    Métadonnées seulement
    Bound-to-continuum and two-phonon resonance quantum-cascade lasers for high duty cycle, high-temperature operation
    (2002)
    Faist, Jérôme
    ;
    Hofstetter, Daniel 
    ;
    Beck, Mattias
    ;
    Aellen, Thierry
    ;
    Rochat, Michel
    ;
    Blaser, Stéphane
    Recent advances in quantum-cascade (QC) laser active-region design are reviewed. Based on a rate equation model of the active region, we show why new gain regions based on a two-phonon resonance or a bound-to-continuum transition exhibit significantly better performance than the traditional design based on a three-quantum-well active region. Threshold current densities as low as 3 kA/cm(2) at T = 300 K, operation with a peak power of 90 mW at 425 K, single-mode high-power operation up to temperatures above 330 K at lambda approximate to 16 mum and continuous wave operation up to T = 311 K are demonstrated. QC lasers able to operate at high duty cycles (50%) on a Peltier cooler were used in a demonstration of a 300-MHz free-space optical link between two buildings separated by 350 m.
  • Publication
    Métadonnées seulement
    Continuous wave operation of a mid-infrared semiconductor laser at room temperature
    (2002)
    Beck, Mattias
    ;
    Hofstetter, Daniel 
    ;
    Aellen, Thierry
    ;
    Faist, Jérôme
    ;
    Oesterle, Ursula
    ;
    Ilegems, Marc
    ;
    Gini, Emilio
    ;
    Melchior, Hans
    Continuous wave operation of quantum cascade lasers is reported up to a temperature of 312 kelvin. The devices were fabricated as buried heterostructure lasers with high-reflection coatings on both laser facets, resulting in continuous wave operation with optical output power ranging from 17 milliwatts at 292 kelvin to 3 milliwatts at 312 kelvin, at an emission wavelength of 9.1 micrometers. The results demonstrate the potential of quantum cascade lasers as continuous wave mid-infrared light sources for high-resolution spectroscopy, chemical sensing applications, and free-space optical communication systems.
  • Publication
    Métadonnées seulement
    Continuous wave operation of a 9.3 mu m quantum cascade laser on a Peltier cooler
    (2001)
    Hofstetter, Daniel 
    ;
    Beck, Mattias
    ;
    Aellen, Thierry
    ;
    Faist, Jérôme
    ;
    Oesterle, Ursula
    ;
    Ilegems, Marc
    ;
    Gini, Emilio
    ;
    Melchior, Hans
    High average power quantum cascade lasers at 9.3 mum using InP top cladding layers and both junction up and junction down mounting are presented. A 3 mm long, junction up mounted device emitted 54 mW average power at 30 degreesC and 11.5% duty cycle with a threshold current density of 3.72 kA/cm(2). A similar, but only 1.5 mm long device with high reflection coating on both facets was mounted junction down and tested at even higher duty cycles. At -27 degreesC, we achieved continuous wave operation with a threshold current density of 3.3 kA/cm(2). (C) 2001 American Institute of Physics.