Inversion-asymmetry-induced interband magneto-optical transitions in HgTe

The first evidence of linear-k term effects in HgTe is reported. New resonance structures observed in interband Γ₆ → Γ₈ magnetoabsorption spectra, for H ∥ [111], can be unambiguously identified with inversion asymmetry- induced transitions.     

Excitonic transitions at forbidden interband edge

Theoretical estimates of the oscillator strengths of optical transitions to s- and p-excitonic levels at a forbidden interband edge are examined critically. Specific example of Cu₂O, is discussed as an illustration. New theoretical estimates based on a k·p analysis are in good agreement with the experimental data.     

Dynamic diffraction and interband transitions in two-dimensional photonic lattices

We reveal a direct link between two fundamental wave phenomena in periodic media, Pendell?sung oscillations and resonant coupling between spectral bands. We experimentally measure the power transfer between laser beams associated with the high-symmetry points in periodic and biased hexagonal photonic lattices. As a result, we demonstrate that Pendell?sung oscillations dominate the dynamics of resonant interband transitions on a short propagation scale.     

Calculated oscillator strength for interband transitions in CuCl

Oscillator strengths calculated for allowed interband transitions of CuCl are presented. The results reflect the identity of the two valence bands which were studied in the previous works.     

Multiphoton interband transitions assisted by photoexcited free carriers

The rate of generation of electron-hole pairs by intense light is calculated within a three-band model of an insulator including a valence band v and conduction bands c and c ₁. It is assumed that the photon energy ?ω is small in comparison with the band gap E _g and generation occurs due to the transitions involving free electrons in the upper conduction band c ₁. It is shown that, at a light intensity j ～ 10¹¹ W/cm² and an electron concentration in the c ₁ band exceeding 10¹⁷ cm^?3, the rates of the transitions c ₁ +l ?ω → ccv (l = 2 or 3) exceed the rates of direct five-photon transitions between the v and the c bands. In this case, a multiphoton avalanche can be initiated.     

Temperature dependence of interband transitions and exchange splitting in nickel

Interband transitions of Ni have been studied as a function of temperature by observing energy losses of low energy electrons reflected from a Ni(100) surface. A threshold is found at E_g ～ 0.15 eV and interpreted as the onset of X^↑₅ → X^↓₂ transitions. The threshold remains unchanged for temperatures up to 900 K. The loss continuum below E_g exhibits an anomalous increase with temperature with a discontinuity in the slope at T ～ 1.2 T_c.     

NIR, MWIR and LWIR quantum well infrared photodetector using interband and intersubband transitions

This paper presents the design, fabrication and characterization of a QWIP photodetector capable of detecting simultaneously infrared radiation within near infrared (NIR), mid wavelength infrared (MWIR) and long wavelength infrared (LWIR). The NIR detection was achieved using interband transition while MWIR and LWIR were based on intersubband transition in the conduction band. The quantum well structure was designed using a computational tool developed to solve self-consistently the Schrödinger–Poisson equation with the help of the shooting method. Intersubband absorption in the sample was measured for the MWIR and LWIR using Fourier transform spectroscopy (FTIR) and the measured peak positions were found at 5.3 μm and 8.7 μm which agree well with the theoretical values obtained 5.0 μm and 9.0 μm for the two infrared bands which indicates the accuracy of the self-consistent model. The photodetectors were fabricated using a standard photolithography process with exposed middle contacts to allow separate bias and readout of signals from the three wavelength bands. The measured photoresponse gave three peaks at 0.84 μm, 5.0 μm and 8.5 μm wavelengths with approximately 0.5 A/W, 0.03 A/W and 0.13 A/W peak responsivities for NIR, MWIR and LWIR bands, respectively. This work demonstrates the possibility of detection of widely separated wavelength bands using interband and intersubband transitions in quantum wells.     

Optical constants and interband transitions in the layer compound InSe

The relevant optical constants of InSe are obtained by applying the Kramers-Kronig relations to accurate near normal incidence reflectance data in the 1.5–5.5 eV energy range. In absence of band calculations, the observed structures are tentatively interpreted by analogy with GaSe ones.     

Observation of double cyclotoron resonance and interband transitions in InAs-GaSb multi-heterojunctions

Magneto-absorption experiments are performed in an InAs-GaSb multiheterojunction where both electrons and holes are simultaneously confined at the interfaces. Oscillatory characteristics are observed and interpreted in terms of interband transitions from the single hole subband to the two lowest electron subbands, and of cyclotron resonances associated with these subbands. Two electron masses are obtained, arising directly as a consequence of the heterojunction potential.     

The dielectric constant associated with direct interband transitions in germanium

An expression for the complex dielectric constant associated with direct interband transitions in germanium has been obtained using a simple model. The model consists of four damped oscillators, and a fit to experimental results for the complex dielectric constant is made to obtain the model parameters, i.e., the oscillator frequencies and damping constants. The results show good agreement with experimental data over a broad range of frequencies.     

Optical properties and interband transitions in the layered compounds SbI3

The optical constants of SbI₃ single crystals, prepared from solution, were calculated from normal incidence reflectance data via a Kramers-Kronig analysis. The dependence of the absorption coefficient on the photon energy suggests the presence of a direct allowed interband transition whereE _g ^d =2·225 eV at room temperature, as well as indirect phonon-assisted transition. The absorption coefficient follows Urbach's empirical relation in the range 2·08–2·34 eV near the intrinsic edge, and a Gaussian shape was obtained near the band maximum. This behaviour is indicative of its excitonic origin and may be contributed to localized excitons in the crystal.     

Evidence of laser-wavelength effect in picosecond ultrasonics: possible connection with interband transitions

We have studied the effect of wavelength change on picosecond acoustic pulses generated using a femtosecond laser. For the first time, we show that the pulse shape can be strongly influenced by the laser wavelength. The results are in excellent agreement with a calculation based on a thermoelastic model which connects them to significant changes in the piezo-optical constants. There are similarities between the present study and stress modulation spectroscopy, which allows us to ascribe the observations to interband transitions and suggests thus a new potentiality of picosecond ultrasonics.     

Optical transitions in strained InAsSb/GaInSb interband QC lasers

In this paper a detailed simulation and theoretical analysis based on model-solid theory and the(→κ)·(→ρ)methodare presented to investigate the dependence of the band structure on the strain deformation in a noveltype-Ⅱ quantum well(QW)heterostructure InAs1_ySby/GaxIn1-xSb under the uniaxial approximation,and subsequently the optical transition and the gain in the interband cascade lasers containing it havebeen evaluated with unchanged injection current densities.The simulation results show that the straineffect on the transition in this heterostructure will not behave as a simple monotonic trend with the latticemismatch of InAs1_ySby/GaxIn1_xSb interface,but as a function of the complex strain chain includingthe whole active region.It is important to the subsequent device design and optimization.     

Dark-bright mixing of interband transitions in symmetric semiconductor quantum dots

In photoluminescence spectra of symmetric [111] grown GaAs/AlGaAs quantum dots in longitudinal magnetic fields applied along the growth axis, we observe in addition to the expected bright states also nominally dark transitions for both charged and neutral excitons. We uncover a strongly nonmonotonic, sign-changing field dependence of the bright neutral exciton splitting resulting from the interplay between exchange and Zeeman effects. Our theory shows quantitatively that these surprising experimental results are due to magnetic-field-induced ±3/2 heavy-hole mixing, an inherent property of systems with C(3v) point-group symmetry.     

Effect of a random deformation-potential field on interband optical transitions

We have calculated the correlation function for the random field caused by the deformation potential due to spherical clusters randomly distributed throughout the sample. We evaluate the characteristic energy which determines the rate at which the interband optical absorption coefficient decreases as the frequency decreases in the neighborhood of the optical tail.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 3–6, February, 1984.     

Ultrashort-pulse-controlled all-optical modulation by interband and intersubband transitions in doped quantum wells

The optimum condition for achieving highly efficient ultrafast all-optical pulse modulation by modification of the absorption of a pulsed interband light field by ultrasubband control-light pulses in a doped quantum well is investigated. The modulation efficiency in the femtosecond domain can be maximized by an intersubband control light with a pulse width (200 fs) that is comparable with the phase-relaxation time of the system and an intensity that is close to the intersubband saturation intensity.