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Journals and Conferences
The transient terahertz radiation emitted by a spin coherence optically generated in CdMnTe two-dimensional electron gases is directly measured in the time domain using electro-optic sampling. The spin radiation decays in a few ps at high magnetic fields.
For future ultrafast all-optical networks, new optical devices are required that directly manipulate communication channels to shift their wavelength over the bandwidth of an optical fiber (50THz). 1,2 Current proposed solutions based on nonlinear processes, however, suffer from small efficiencies owing to low nonlinear susceptibilities. 3 Here, we… (More)
A terahertz quantum cascade laser and an integrated Auston-switch are coupled to perform ultrafast gain switching. The resulting non-equilibrium gain is not clamped above laser threshold and large amplification of input terahertz pulses is demonstrated.
A 3.1THz phonon depopulation-based quantum-cascade-laser is investigated using terahertz time domain spectroscopy. A gain of 25cm<sup>-1</sup> and absorption features due to the lower laser level being populated from a parasitic electronic channel are highlighted.
Terahertz pulse generation is demonstrated by a resonant femtosecond interband excitation of the miniband of a quantum-cascade-laser. The laser gain is subsequently used to amplify the terahertz pulse generated as it propagates through the cavity.
We present a study on the intersublevel spacings of electrons and holes in a single layer of InAs self-assembled quantum dots. We use Fourier transform infrared transmission spectroscopy via a density chopping scheme for direct experimental observation of the intersublevel spacings of electrons without any external magnetic field. Epitaxial,… (More)
A novel scheme to achieve mode-locking of a multimode laser is demonstrated. Traditional methods to produce ultrashort laser pulses are based on modulating the cavity gain or losses at the cavity roundtrip frequency, favoring the pulsed emission. Here, we rather directly act on the phases of the modes, resulting in constructive interference for the… (More)
The QCL carrier phase is set by coherent injection seeding with a THz pulse. This enables the phase-resolved laser emission to be measured in the time-domain and the QCL to be used directly for time-domain-spectroscopy.
We used a terahertz (THz) quantum cascade laser (QCL) as an integrated injection seeded source and amplifier for THz time-domain spectroscopy. A THz input pulse is generated inside a QCL by illuminating the laser facet with a near-IR pulse from a femtosecond laser and amplified using gain switching. The THz output from the QCL is found to saturate upon… (More)
We probed, in the time domain, the THz electromagnetic radiation originating from spins in CdMnTe diluted magnetic semiconductor quantum wells containing high-mobility electron gas. Taking advantage of the efficient Raman generation process, the spin precession was induced by low power near-infrared pulses. We provide a full theoretical first-principles… (More)