We have studied intersubband absorption in strain compensated InxGa12xAs/AlAs/InyAl12yAs multiple quantum wells and superlattices grown on InP. X-ray diffraction shows that the layers are pseudomorphically strained and exhibit slight compositional grading of the interfaces. Owing to the high AlAs barriers, the intersubband absorption can be tailored to wavelengths shorter than 2 mm. In some sam...

Improving the performance of the QCL through block diagram as well as mathematical models is the main scope of this paper. In order to enhance the performance of the underlined device, the mathematical model parameters are used in a reliable manner in such a way that the optimum behavior was achieved. These parameters play the central role in specifying the optical characteristics of the consid...

Terahertz quantum cascade laser sources based on intra-cavity difference-frequency generation are currently the only room-temperature mass-producible diode-laser-like emitters of coherent 1-6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt-level power output and broad tuning from 1.2 to 5.9 THz, all at room-temperature. Terahertz output in ...

In this thesis I investigated the feasibility of an optically pumped intersubband farinfrared (40-100 j,lm) laser, using GaAs/ AlxGal-xAs heterostructures. The proposed design aims to use LO-phonon-mediated depopulation of the lower THz laser level to aid the intersubband laser population inversion. Interband recombination occurs by means of stimulated emission, thus combining an interband (rv ...

We have investigated the intersubband transitions of surface state electrons (SSE) on liquid He induced by microwave radiation at temperatures from 1.1 K down to 0.01 K. Above 0.4 K, the transition linewidth is proportional to the density of He vapor atoms. This proportionality is explained well by Ando’s theory, in which the linewidth is determined by the electron vapor atom scattering. Howeve...

Spin-resolved cyclotron resonance is observed in InSb/AlInSb quantum-well heterostructures. Spin-resolved transitions are identified for fields greater than 2.2 T and confirmed by k ·p modeling. The cyclotron effective mass is calculated for a range of fields up to 11.5 T and is indicative of the strong nonparabolicity in this material. Resonant coupling is observed between the ground and first...

We propose and analyze an efficient scheme for suppressing the absorption of a weak probe field based on intersubband transitions in a four-level asymmetric coupled-quantum well (CQW) driven coherently by a probe laser field and a control laser field. By using the numerical simulation, we find that the magnitude of the transient absorption of the probe field is smaller than the three-level syst...

A process for the growth of uniform boron-doped Si/SiGe multiple quantum wells by rapid thermal chemical vapor deposition (RTCVD) for studying intersubband transitions for quantum cascade laser applications has been developed. The doping density profiles are extremely sharp (~2 nm/decade and ~3 nm/decade for the leading and trailing boron edges, respectively) measured by high resolution seconda...

Quantum cascade detectors (QCDs) are mid-infrared and far-infrared, low-noise, photovoltaic utilizing intersubband transitions. This Letter presents an InAs/AlAs0.16Sb0.84 based QCD lattice matched to InAs substrate. material system exhibits properties like a low effective electron mass of the well 0.023 m0, beneficial for higher optical absorption strength, high conduction band offset 2.1 eV, ...

We study intersubband spin density collective modes in double-layer quantum Hall systems at ν = 2 within the time-dependent Hartree-Fock approximation. We find that these intersubband spin density excitations may soften under experimentally accessible conditions, signaling a phase transition to a new quantum Hall state with interlayer inplane antiferromagnetic spin correlations. We show that th...