Abstract
Radio-frequency modulated terahertz (THz) emission power from weakly-coupled GaAs/AlGaAs superlattice (SL) has been increased by parallel connection of several SL mesas. Each SL mesa is a self-oscillator with its own oscillation frequency and mode. In coupled non-identical SL mesas biased at different voltages within the hysteresis loop the chaotic, quasiperiodic and frequency-locked modes of self-oscillations of current arise. THz emission was detected when three connected in parallel SL mesas were biased into the frequency-locked and quasiperiodic modes of self-oscillations of current, while in the chaotic mode of those it falls to the noise level.
Highlights
Terahertz (THz) frequency range attracts considerable attention for numerous applications such as information and communication technologies, biology and medical sciences, nondestructive evaluation and security
The THz sources based on intracavity difference-frequency generation (DFG) in dual-wavelength mid-infrared quantum cascade lasers (QCLs) (THz DFGQCLs) operate at room temperature
The THz emission power from the SL was detected with a fast NbN hot-electron bolometer (HEB)
Summary
Terahertz (THz) frequency range attracts considerable attention for numerous applications such as information and communication technologies, biology and medical sciences, nondestructive evaluation and security. The highest reported frequency of RTDs is 1.92 THz with an output power of approximately 0.4 μW at room temperature for a 12-μm-long slot antenna.. Despite many efforts having been put in for elevation of operating temperature of THz quantum cascade lasers (QCLs), the highest reported temperature is 199 K3 and 129 K4 for pulsed and continuous-wave (CW) modes, respectively. The THz sources based on intracavity difference-frequency generation (DFG) in dual-wavelength mid-infrared QCLs (THz DFGQCLs) operate at room temperature.. The threshold current density of about 1 kA/cm reduces the THz emission power due to the overheating of the laser structure. The lowest threshold current density of 0.89 kA/cm and 1.3 kA/cm in pulsed and CW modes has been reached in THz DFG-QCL emitting at 2.92
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