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We present a mid-infrared quantum cascade laser embedded into a micro-strip line for high frequency modulation. Modulating with less than 10mW at the round trip frequency, we observe beat-note injection locking within a range in the order of 1 MHz.
CEA-Leti has developed a real-time reflection imaging system: it combines illumination by QCL sources and a telescope that focuses the reflected radiation onto a camera that houses an uncooled 320×240 antenna-coupled micro-bolometer array driven by a FPGA card. We present first high resolution images of illuminated surfaces acquired in real-time.
We demonstrate coherent detection of the emission from a terahertz frequency quantum cascade laser which is actively mode-locked by modulating its bias-current with a microwave synthesizer. Coherent sampling of the terahertz pulse train is achieved by phase-locking the repetition rate and the carrier frequency of the terahertz quantum cascade laser to the repetition rate of the of a commercial erbium-doped...
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.
Electro-optic sampling in ZnTe is used to phase-lock the line of a 2.5 THz quantum cascade laser to the repetition rate of a femtosecond fibre laser and to perform an absolute measurement of the laser emission frequency.
Integrated THz pulse generation and amplification in THz QCLs is demonstrated. Intracavity narrowband THz pulses are generated at 2.1THz by exciting the facet of a THz quantum cascade laser with a resonant interband-intersubband transition and detected using electro-optic sampling.
We demonstrate that the cavity resonance frequency - the round-trip frequency - of terahertz quantum cascade lasers can be injection-locked by direct modulation of the bias current using an RF source. Metal-metal and single-plasmon waveguide devices with roundtrip frequencies up to 35GHz have been studied, and show locking ranges above 200MHz. Inside this locking range the laser round-trip frequency...
This paper presents a CW raster-scanning THz imaging setup used to perform Non-Destructive Testing of Kevlar™ and carbon fibre samples. The setup uses a 2.5 THz Quantum Cascade Laser as a source. Delamination defect in a Kevlar sample was detected showing a sensitivity to laser polarization orientation. Detection of a break in a carbon/epoxy sample was also performed.
The population inversion of a terahertz quantum cascade laser is placed out of equilibrium using an integrated Auston switch. As a result, the dynamic gain of the laser is no longer clamped at threshold by the mirror losses, and large amplification of input terahertz probe pulses is observed.
We demonstrate the phase-locking of Quantum Cascade Lasers emitting at 2.4 and 2.7Terahertz, to the repetition rate of a commercial Er-doped fiber-fs-laser. We observe a linewidth of the beat-note signal with a signal-to-noise of 80dB in 1Hz bandwidth.
We have used the Pockels effect in ZnTe to demonstrate that the frequency and the phase of a 2.7Terahertz Quantum Cascade Laser can be actively stabilized to the n-th harmonic of the 90MHz repetition rate of a commercial, mode-locked Er-doped fiber-laser. The beating between the stabilized QCL frequency and the harmonic of the repetition rate yielded a signal-to-noise ratio of 80dB in 1Hz bandwidth...
We have used the Pockels effect in ZnTe to demonstrate that the frequency and the phase of Quantum Cascade Lasers emitting at 2.4 and 2.7 Terahertz can be actively stabilized to the n-th harmonic of the 90 MHz repetition rate of a commercial, mode-locked Er-doped fiber-laser. The beating between the stabilized QCL frequency and the harmonic of the repetition rate yielded a signal-to-noise ratio >;...
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.
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.
We demonstrate the phase-locking of a 2.7Terahertz Quantum Cascade Laser to the repetition rate of a commercial Er-doped fiber-fs-laser. We observe a linewidth of the beatnote signal with a signal-to-noise of 80dB in 1Hz bandwidth.
It is demonstrated that the cavity resonance frequency - the round-trip frequency - of terahertz quantum cascade lasers can be injection-locked by direct modulation of the bias current using an RF source. Metal-metal and single-plasmon waveguide devices with round-trip frequencies up to 35-GHz have been studied, and show locking ranges above 200-MHz. A square-root dependence of the locking range with...
Quantum Cascade Lasers (QCL) are probably the most promising sources for Terahertz wave generation. The key issue especially for double metal QCLs is the extraction and the beam shaping of the emitted power. We propose a solution with a TEM-Horn Antenna and we compare it to the most recently proposed solutions: plasmonic array, Silicon-lens etc. New Terahertz antenna designs will also be presented.
We report on the high frequency modulation of terahertz (THz) quantum cascade lasers (QCLs). By resonantly enhancing the frequency response of the RF biasing circuit we show that 4 mm and 1.5 mm-long metal-metal waveguide 2.3 THz QCLs, can be modulated up to 21 and 24 GHz respectively.
We demonstrate single-mode, surface-emitting terahertz lasers at lambdaap110 mum employing photonic-crystal resonators. The devices employ metal-metal waveguides, and the photonic-crystal lattice is implemented by the sole patterning of the top metal contact, without deep-etching the semiconductor in the photonic crystal holes. The device emission wavelength correctly tunes with the photonic crystal...
We demonstrate full control of the spectral and spatial emission properties of terahertz quantum cascade lasers using metallic photonic-crystals for lateral confinement. Single-mode, surface-emission is obtained at a frequency of 2.8-2.9 THz using a photonic-crystal design with a square lattice geometry. The resonator quality factor is then optimised, using a graded photonic-crystal architecture,...
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