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Hofstetter, Daniel

Nom
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
    Accès libre
    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/cm2 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 λ ≈ 16 μm 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
    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
    Accès libre
    Distributed-feedback quantum cascade lasers emitting in the 9-μm band with InP top cladding layers
    (2002)
    Hofstetter, Daniel 
    ;
    Beck, Mattias
    ;
    Aellen, Thierry
    ;
    Faist, Jérôme
    ;
    Oesterle, Ursula
    ;
    Ilegems, Marc
    ;
    Gini Emilio
    ;
    Melchior, Hans
    Two different high performance quantum cascade distributed-feedback lasers with four quantum-well-based active regions and InP top cladding layers are presented. The first device, which emitted at 9.5 μm, was mounted junction down in order to get high average powers of up to 71 mW at -30°C and 30 mW at room temperature. The other device, which lased at 9.1 μm, was optimized for high pulsed operating temperatures and tested up to 150°C at 1.5% duty cycle. The emission of both lasers stayed single mode with more than 20-dB side-mode suppression ratio over the entire investigated power and temperature range.