Frequency modulations due to domain dynamics in terahertz quantum cascade lasers

Origin of terminal voltage variations due to self-mixing in terahertz frequency quantum cascade lasers.

We explain the origin of voltage variations due to self-mixing in a terahertz (THz) frequency quantum cascade laser (QCL) using an extended density matrix (DM) approach. Our DM model allows calculation of both the current-voltage (I-V) and optical power characteristics of the QCL under optical feedback by changing the cavity loss, to which the gain of the active region is clamped. The variation...

Nanowire terahertz quantum cascade lasers

Ultrafast population dynamics in electrically modulated terahertz quantum cascade lasers

The ultrafast population dynamics in electrically modulated threewell terahertz quantum cascade lasers (QCLs) is studied by using the selfconsistent Bloch–Poisson equations. In the modulation process, the nonequilibrium oscillations of the population inversion are found before the population equilibrium recovers. The equilibrium formation time increases nonlinearly with the period number. This ...

Time domain modeling of terahertz quantum cascade lasers for frequency comb generation.

The generation of frequency combs in the mid-infrared and terahertz regimes from compact and potentially cheap sources could have a strong impact on spectroscopy, as many molecules have their rotovibrational bands in this spectral range. Thus, quantum cascade lasers (QCLs) are the perfect candidates for comb generation in these portions of the electromagnetic spectrum. Here we present a theoret...

Terahertz photonic crystal quantum cascade lasers.

We combine photonic crystal and quantum cascade band engineering to create an in-plane laser at terahertz frequency. We demonstrate that such photonic crystal lasers strongly improve the performances of terahertz quantum cascade material in terms of threshold current, waveguide losses, emission mode selection, tunability and maximum operation temperature. The laser operates in a slow-light regi...