New semiconductor laser designs and the exploratory investigation of the terahertz frequency range

Abstract

We study thermodynamic quantities and the stability of a black hole in a cavity using the Euclidean action formalism by Gibbons and Hawking based on the generalized uncertainty relation which is extended in a symmetric way with respect to the space and momentum without loss of generality. Two parameters in the uncertainty relation affect the thermodynamical quantities such as energy, entropy, and the heat capacity. In particular, it can be shown that the small black hole is unstable and it may decay either into a minimal black hole or a large black hole. We discuss a constraint for a large black hole comparable to the size of the cavity in connection with the critical mass.

Two faces of superradiance in tandem-cavity ridge waveguide heterostructures

“…Reaching SR in solids is a more challenging because of the short dephasing time T2 enabling only partial macroscopic correlations across a sample [4]. Realization of SR in 2D (and 3D) semiconductor heterostructures is a very controversial topic [5]. The short carrier dephasing time (T2~100 fs) is usually believed to prohibit any macroscopically coherent processes in 2D or 3D semiconductor medium [6].…”

Far-Infrared Few-Cycle-Pulse Generation in Quantum-Well Heterostructures under Femtosecond Laser Pumping

“…For typical GaAs/AlGaAs or InGaAs/GaAs structures, the frequencies of the interband transitions, ω 21 and ω 31 , lie in the near-infrared (optical) region, λ ≈ 0.8−1 µm, whereas the frequency of the intersubband transition, ω 32 , can be varied in a wide range -from mid-infrared to far-infrared, λ IR ≈ 5−100 µm, and to the THz region. In symmetrical QWs, all three transitions may be dipole allowed due to mixing of heavy and light holes [20,22]. An essential point of the schematic given is that the mean frequency of the pump pulse, ω, is close to the frequencies of the interband transitions, ω 21 and ω 31 , and the width of the pump pulse spectrum is large enough to span the difference between them, ω 32 .…”

“…few-cycle or single-cycle, mid/far-infrared pulses. Recently we suggested the use of the resonant nonlinear-wave mixing inside a semiconductor laser cavity as a basis for the new kind of continuous-wave room temperature mid/far-infrared lasers [18][19][20]. There was also an observation of the 10-to 20-cycle, i.e.…”