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We have phase locked a 4.7 THz Quantum Cascade Laser (QCL) to a stable microwave reference signal. The QCL is a 3rd order distributed feedback (DFB) laser with a low power consumption of 0.5 W and radiation power of about 0.25 mW. One of the key elements in our experimental setup is a superlattice diode operating as a harmonic mixer and providing the beat signal between the QCL and the 24th harmonic...
We report on a phase locking experiment of a 3.4 THz Quantum Cascade Laser (QCL) by using only room temperature electronics. A super-lattice harmonic mixer was used to produce a bit signal between the QCL signal and the 18th harmonic of a 190 GHz reference generator. The beat signal more than 30 dB above the noise level for 1 MHz RBW was observed. Such a signal to noise ratio was sufficient to provide...
The density matrix based model is employed to design a THz quantum cascade laser with optimized oscillator strength and improved injection tunneling. A maximum operating temperature of 199.5 K has been recorded at 3.22 THz (1.28ħω/kB).
We investigate techniques to manipulate the frequency of Terahertz Quantum Cascade Lasers (THz QCL). Frequency tuning by changing the heatsink temperature or the QCL drive current, or by illumination of the QCL with bandgap light. Creation of frequency sidebands through amplitude modulation of the drive current or the bandgap light. We report the observation of strong difference frequency generation...
We studied the phase locking and spectral linewidth of a 2.7 THz quantum cascade laser by mixing its two lateral lasing modes using a superconducting bolometer mixer.
Highly divergent radiation is expected from lasers with sub-wavelength apertures due to diffraction. However the short range variations of intensity have been observed in the far field of THz quantum cascade lasers with sub-wavelength apertures. We developed an antenna model for long lasers with subwavelength transverse dimensions (wire lasers). Based on this model we show that the observed far field...
We report the development of a quantum cascade laser at the longest wavelength to date, /spl lambda/=87.2 m (3.44 THz), that uses longitudinal-optical phonon scattering for electron depopulation. Operating in pulsed mode, lasing is obtained up to sixty-four Kelvin.
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