Tunable cyclotron-resonance laser in germanium

Unterrainer, K.; Kremser, Christian; Gornik, E.; Pidgeon, C. R.; Ivanov, Yu. L.; Haller, E. E.

doi:10.1103/physrevlett.64.2277

Cited by 42 publications

(8 citation statements)

References 12 publications

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“…These may be found, for instance, in different narrow-gap materials or in the valence band of zinc-blende semiconductors. So far, stimulated cyclotron emission has only been achieved in the valence band of bulk germanium, subjected to crossed electric and magnetic fields 17 , alas in the regime close to the electrical breakdown of this material. In other attempts, quantum cascade structures have also been tested to achieve efficient cyclotron emission 18,19 .…”

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confidence: 99%

Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons

et al. 2019

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The Landau level laser has been proposed a long time ago as a unique source of monochromatic radiation, widely tunable in the THz and infrared spectral ranges using an externally applied magnetic field. In spite of decades of efforts, this appealing concept never resulted in the design of a reliable device. This is due to efficient Auger scattering of Landau-quantized electrons, which is an intrinsic non-radiative recombination channel that eventually gains over cyclotron emission in all materials studied so far: in conventional semiconductors with parabolic bands, but also in graphene with massless electrons. The Auger processes are favored in these systems by Landau levels (or their subsets) equally spaced in energy.Here we show that this scheme does not apply to massless Kane electrons in gapless HgCdTe alloy, in which undesirable Auger scattering is strongly suppressed and the sizeable cyclotron emission observed, for the first time in the case of massless particles. The gapless HgCdTe thus appears as a material of choice for future technology of Landau level lasers.

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confidence: 99%

Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons

et al. 2019

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“…In order to estimate the population inversion conditions, we assume inducing a gain comparable to that of THz p-Germanium lasers. The latter has typically a gain coefficient 70 𝛾 = 𝑁B𝜆 < 4𝜋 < ⁄ 𝜏 I" 𝛥𝜈E of the order of 0.05 cm −1 [ 71,72 ], where 𝑁 corresponds to the population difference, 𝜆 is the wavelength of light in the medium and 𝛥𝜈 = 1 2𝜋 ⁄ 𝜏 • . In the case of relativistic electrons, the spontaneous cyclotron radiative lifetime can be appraised as follows 73 : 𝜏 I" 8`= 𝛼 j -u k < 𝜔 u , where 𝛼 is the fine structure constant, 𝑣 p and c are the Fermi and light velocities, respectively.…”

Section: Discussionmentioning

confidence: 99%

Terahertz cyclotron emission from two-dimensional Dirac fermions

et al. 2023

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Since the emergence of graphene, we have seen several proposals for the realization of Landau lasers tunable over the terahertz frequency range. The hope was that the non-equidistance of the Landau levels from Dirac fermions would suppress the harmful non-radiative Auger recombination. Unfortunately, even with this non-equidistance an unfavorable non-radiative process persists in Landau-quantized graphene, and so far no cyclotron emission from Dirac fermions has been reported. One way to eliminate this last non-radiative process is to sufficiently modify the dispersion of the Landau levels by opening a small gap in the linear band structure. A proven example of such gapped graphene-like materials are HgTe quantum wells close to the topological phase transition. In this work, we experimentally demonstrate Landau emission from Dirac fermions in such HgTe quantum wells, where the emission is tunable by both the magnetic field and the carrier concentration. Consequently, these results represent an advance in the realization of terahertz Landau lasers tunable by magnetic field and gate-voltage.

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“…Far-infrared lasing was observed on transitions between Landau levels of the light-hole and heavy-hole valence band in p-type germanium in crossed electric and magnetic fields [48,49]. This mechanism provides narrow band far-infrared generation which is linearly tunable by the magnetic field strength and yields output powers of several 100 mW [50,51]. In the last decade p-type inter-valence band lasers were optimized to yield picosecond pulses [52,53] at low magnetic fields [54].…”

Section: Nonlinear Spectroscopy On Shallow Donor Transitionsmentioning

confidence: 99%

Nonlinear THz Spectroscopy of n-Type GaAs

Gaal

Reimann

Woerner

et al. 2007

Ultrafast Phenomena XV

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In this thesis, the ultrafast dynamics of conduction band electrons in semiconductors are investigated by nonlinear terahertz (THz) spectroscopy. In particular, n-doped gallium arsenide samples with doping concentrations in the range of 10 16 cm −3 to 10 17 cm −3 are studied. A novel source for the generation of intense THz radiation is developed which yields single-cycle THz transients with field amplitudes of more then 400 kV/cm. The THz source uses ultrashort optical laser pulses provided by a Ti:sapphire oscillator. In addition, a two-color THz-pump mid-infrared-probe setup is implemented, which allows for two-dimensional time-resolved experiments in the far-infrared wavelength range. Field ionization of neutral shallow donors in gallium arsenide with intense, ultrashort THz pulses and subsequent coherent radiative recombination of electrons to impurity ground states is observed at room temperature. The superradiant decay of the nonlinear polarization results in the emission of a coherent signal with picosecond lifetimes. Such nonlinear signals, which exhibit a lifetime ten times longer than in the linear regime are observed for the first time. At low temperatures and THz field strengths below 5 kV/cm, Rabi flopping on shallow donor transitions is demonstrated. For the first time, the polar electron-LO phonon interaction is directly measured in the quantum kinetic transport regime. Quasi-instantaneous acceleration of conduction band electrons in the polar gallium arsenide lattice by the electric field of intense THz pulses and subsequent probing of the mid-infrared transmission reveals a modulation of the transmission along the THz-mid-infrared delay coordinate with the frequency of the LO phonon. These modulations directly display the relative phase between the electron motion and its surrounding virtual phonon cloud. Quantum kinetic model calculations fully account for the observed phenomena.

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Tunable cyclotron-resonance laser in germanium

Cited by 42 publications

References 12 publications

Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons

Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons

Terahertz cyclotron emission from two-dimensional Dirac fermions

Nonlinear THz Spectroscopy of n-Type GaAs

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