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Search Results: 1 - 10 of 454986 matches for " Jér?me Faist "
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Sequential resonant tunneling in quantum cascade lasers
Romain Terazzi,Tobias Gresch,Andreas Wittmann,Jérme Faist
Physics , 2008, DOI: 10.1103/PhysRevB.78.155328
Abstract: A model of sequential resonant tunneling transport between two-dimensional subbands that takes into account explicitly elastic scattering is investigated. It is compared to transport measurements performed on quantum cascade lasers where resonant tunneling processes are known to be dominating. Excellent agreement is found between experiment and theory over a large range of current, temperature and device structures.
Octave-spanning semiconductor laser
Markus R?sch,Giacomo Scalari,Mattias Beck,Jérme Faist
Physics , 2014, DOI: 10.1038/nphoton.2014.279
Abstract: We present here a semiconductor injection laser operating in continuous wave with an emission covering more than one octave in frequency, and displaying homogeneous power distribution among the lasing modes. The gain medium is based on a heterogeneous quantum cascade structure operating in the THz range. Laser emission in continuous wave takes place from 1.64 THz to 3.35 THz with optical powers in the mW range and more than 80 modes above threshold. Free-running beatnote investigations on narrow waveguides with linewidths of 980 Hz limited by jitter indicate frequency comb operation on a spectral bandwidth as wide as 624 GHz, making such devices ideal candidates for octave-spanning semiconductor-laser-based THz frequency combs.
Ultra strong coupling regime and plasmon-polaritons in parabolic semiconductor quantum wells
Markus Geiser,Fabrizio Castellano,Giacomo Scalari,Mattias Beck,Laurent Nevou,Jérme Faist
Physics , 2011, DOI: 10.1103/PhysRevLett.108.106402
Abstract: Ultra strong coupling is studied in a modulation-doped parabolic potential well coupled to an inductance-capacitance resonant circuit. In this system, in accordance to Kohn's theorem, strong reduction of the energy level separation caused by the electron-electron interaction compensates the depolarization shift. As a result, a very large ratio of 27% of the Rabi frequency to the center resonance frequency as well as a polariton gap of width 2? ? 670GHz are observed, suggesting parabolic quantum wells as the system of choice in order to explore the ultra-strong coupling regime.
Sub-cycle measurement of intensity correlations in the Terahertz range
Ileana-Cristina Benea-Chelmus,Curdin Maissen,Giacomo Scalari,Mattias Beck,Jérme Faist
Physics , 2015,
Abstract: The Terahertz frequency range bears intriguing opportunities, beyond very advanced applications in spectroscopy and matter control. Peculiar quantum phenomena are predicted to lead to light emission by non-trivial mechanisms. Typically, such emission mechanisms are unraveled by temporal correlation measurements of photon arrival times, as demonstrated in their pioneering work by Hanbury Brown and Twiss. So far, the Terahertz range misses an experimental implementation of such technique with very good temporal properties and high sensitivity. In this paper, we propose a room-temperature scheme to measure photon correlations at THz frequencies based on electro-optic sampling. The temporal resolution of 146 fs is faster than one cycle of oscillation and the sensitivity is so far limited to ~1500 photons. With this technique, we measure the photon statistics of a THz quantum cascade laser. The proposed measurement scheme allows, in principle, the measurement of ultrahigh bandwidth photons and paves the way towards THz quantum optics.
Room temperature terahertz polariton emitter
Markus Geiser,Giacomo Scalari,Fabrizio Castellano,Mattias Beck,Jérme Faist
Physics , 2012, DOI: 10.1063/1.4757611
Abstract: The strong-coupling regime between an electronic transition and the photonic mode of a optical resonator manifests itself in the lifting of the degeneracy between the two modes and the creation of two polariton states with mixed optical and electronic character. This phenomenon has been studied in atoms, excitons in semiconductors and quantum electrodynamics circuits based on Josephson junctions. Recently, there is also strong interest to study similar e?ects using intersubband transitions in quantum wells in the terahertz, where the ultra strong coupling regime can be reached and new physical e?ects have been predicted. An other interesting feature of this system is that, in contrast to systems based on superconductors, the ultra strong coupling regime can be maintained up to room temperature. In this work, we demonstrate that parabolic quantum wells coupled to LC circuit resonators in the ultra strong coupling regime can achieve terahertz emission up to room temperature.
Quantum Cascade Laser Frequency Combs
Jérme Faist,Gustavo Villares,Giacomo Scalari,Markus R?sch,Christopher Bonzon,Andreas Hugi,Mattias Beck
Physics , 2015,
Abstract: It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the first dual-comb spectroscopy measurements. The capability of the structure to integrate monolithically non-linear optical element as well as to operate as a detector show great promise for future chip integration of dual-comb systems.
Dispersion engineering of Quantum Cascade Lasers frequency combs
Gustavo Villares,Sabine Riedi,Johanna Wolf,Dmitry Kazakov,Martin J. Süess,Mattias Beck,Jérme Faist
Physics , 2015,
Abstract: Quantum cascade lasers are compact sources capable of generating frequency combs. Yet key characteristics - such as optical bandwidth and power-per-mode distribution - have to be improved for better addressing spectroscopy applications. Group delay dispersion plays an important role in the comb formation. In this work, we demonstrate that a dispersion compensation scheme based on a Gires-Tournois Interferometer integrated into the QCL-comb dramatically improves the comb operation regime, preventing the formation of high-phase noise regimes previously observed. The continuous-wave output power of these combs is typically $>$ 100 mW with optical spectra centered at 1330 cm$^{-1}$ (7.52 $\mu$m) with $\sim$ 70 cm$^{-1}$ of optical bandwidth. Our findings demonstrate that QCL-combs are ideal sources for chip-based frequency comb spectroscopy systems.
On-chip Dual-comb based on Quantum Cascade Laser Frequency Combs
Gustavo Villares,Johanna Wolf,Dmitry Kazakov,Martin J Süess,Andreas Hugi,Mattias Beck,Jérme Faist
Physics , 2015,
Abstract: Dual-comb spectroscopy is emerging as one of the most appealing applications of mid-infrared frequency combs for high-resolution molecular spectroscopy, as it leverages on the unique coherence properties of frequency combs combined with the high sensitivities achievable by mid-infrared molecular spectroscopy. Here we present an on-chip dual-comb source based on mid-infrared quantum cascade laser frequency combs, where two frequency combs are integrated on a single chip. Control of the combs repetition and offset frequencies is obtained by integrating micro-heaters next to each laser. We show that a full control of the dual-comb system is possible, by measuring a multi-heterodyne beating corresponding to an optical bandwidth of 32 cm$^{-1}$ at a center frequency of 1330 cm$^{-1}$ (7.52 $\mu$m), demonstrating that this device is ideal for compact dual-comb spectroscopy systems.
Observation of Zone-Folded Acoustic Phonons in Terahertz Quantum Cascade Lasers using Picosecond Ultrasonics
Axel Bruchhausen,Mike Hettich,James Lloyd-Hughes,Milan Fischer,Mattias Beck,Giacomo Scalari,Jérme Faist,Thomas Dekorsy
Physics , 2010,
Abstract: We have investigated the time-resolved vibrational properties of terahertz quantum cascade lasers by means of ultra-fast laser spectroscopy. By the observation of the acoustic folded branches, and by analyzing the involved phonon modes it is possible to extract accurate structural information of these devices, which are essential for their design and performance.
Direct surface cyclotron resonance terahertz emission from a quantum cascade structure
Fran?ois-Régis Jasnot,Louis-Anne De Vaulchier,Yves Guldner,Gérald Bastard,Angela Vasanelli,Christophe Manquest,Carlo Sirtori,Mattias Beck,Jérme Faist
Physics , 2012, DOI: 10.1063/1.3692572
Abstract: A strong magnetic field applied along the growth direction of a semiconductor quantum well gives rise to a spectrum of discrete energy states, the Landau levels. By combining quantum engineering of a quantum cascade structure with a static magnetic field, we can selectively inject electrons into the excited Landau level of a quantum well and realize a tunable surface emitting device based on cyclotron emission. By applying the appropriate magnetic field between 0 and 12 T, we demonstrate emission from a single device over a wide range of frequencies (1-2 THz and 3-5 THz).
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