10 research outputs found
Photovoltaic Probe of Cavity Polaritons in a Quantum Cascade Structure
The strong coupling between an intersubband excitation in a quantum cascade
structure and a photonic mode of a planar microcavity has been detected by
angle-resolved photovoltaic measurements. A typical anticrossing behavior, with
a vacuum-field Rabi splitting of 16 meV at 78K, has been measured, for an
intersubband transition at 163 meV. These results show that the strong coupling
regime between photons and intersubband excitations can be engineered in a
quantum cascade opto-electronic device. They also demonstrate the possibility
to perform angle-resolved mid-infrared photodetection and to develop active
devices based on intersubband cavity polaritons.Comment: submitted to Applied Physics Letter
Direct surface cyclotron resonance terahertz emission from a quantum cascade structure
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)
Measurement of the intrinsic linewidth of terahertz quantum cascade lasers using a near- infrared frequency comb
We report the measurement of the frequency noise power spectral density of a quantum cascade laser emitting at 2.5THz. The technique is based on heterodyning the laser emission frequency with a harmonic of the repetition rate of a near-infrared laser comb. This generates a beatnote in the radio frequency range that is demodulated using a tracking oscillator allowing measurement of the frequency noise. We find that the latter is strongly affected by the level of optical feedback, and obtain an intrinsic linewidth of ~230Hz, for an output power of 2mW
Coherent sampling of active mode-locked terahertz quantum cascade lasers and frequency synthesis
International audienceTerahertz quantum cascade lasers are compact, electrically pumped semiconductor laser sources that are capable of delivering tens of milliwatts of power in continuous wave. Here, we demonstrate that these devices can be operated in a regime of active mode-locking by modulating their bias current with a radiofrequency synthesizer. Detection of the emitted pulse train is made possible by phase-locking the quantum cascade laser repetition rate and carrier frequency to a harmonic of the repetition rate of a mode-locked femtosecond fibre laser. This technique allows coherent sampling of the terahertz electric field, showing that the terahertz pulses are transform-limited. In addition, our technique allows control of the carrier-envelope phase shift of the quantum cascade laser
Tunable surface emitting THz quantum cascade structure based on cyclotron emission
International audienc
Erratum: Coherent sampling of active mode-locked terahertz quantum cascade lasers and frequency synthesis
Injection-locking of terahertz quantum cascade lasers up to 35GHz using RF amplitude modulation
Coherent sampling of active mode-locked terahertz quantum cascade lasers and frequency synthesis
International audienceTerahertz quantum cascade lasers are compact, electrically pumped semiconductor laser sources that are capable of delivering tens of milliwatts of power in continuous wave. Here, we demonstrate that these devices can be operated in a regime of active mode-locking by modulating their bias current with a radiofrequency synthesizer. Detection of the emitted pulse train is made possible by phase-locking the quantum cascade laser repetition rate and carrier frequency to a harmonic of the repetition rate of a mode-locked femtosecond fibre laser. This technique allows coherent sampling of the terahertz electric field, showing that the terahertz pulses are transform-limited. In addition, our technique allows control of the carrier-envelope phase shift of the quantum cascade laser