Low temperature photoluminescence (PL) from InP1-xBix thin films with Bi concentrations in the 0-2.49% range reveals anomalous spectral features with strong and very broad (linewidth of 700 nm) PL signals compared to other bismide alloys. Multiple transitions are observed and their energy levels are found much smaller than the band-gap measured from absorption measurements. These transitions ar...

Ultrashort pulses of intense, coherent, and tunable far-infrared and mid-infrared radiation, achievable with freeelectron lasers and optical parametric amplifiers, provide unique opportunities to investigate low energy dynamics in solids. This paper reviews our recent experiments on bulk and quantum-confined semiconductors using such radiation. These experiments include: far-infrared spectrosco...

We present an X-ray-optical cross-correlator for the soft ([Formula: see text]) up to the hard X-ray regime based on a molybdenum-silicon superlattice. The cross-correlation is done by probing intensity and position changes of superlattice Bragg peaks caused by photoexcitation of coherent phonons. This approach is applicable for a wide range of X-ray photon energies as well as for a broad range...

The dynamical evolution of a moving three-level atom in K-configuration interacting with two quantized modes (or one quantized mode and a classical field) in coherent states inside an ideal cavity is studied using density matrix equations. The spatial field mode structures of the cavity are taken into account in this study. We also discuss analytic results under certain parametric conditions pe...

The generation of midinfrared pulses through the optical rectification extended the radiation frequency from a few THz to several tens of THz. The coherent measurement of a detection frequency greater than 5 THz was demonstrated using a GaP and a ZnTe electro-optic sensor. This optoelectronic technique opens the door to the midinfrared ~midIR! region for coherent emission spectroscopy, time-dom...

Many crystalline solids possess strongly anharmonic ``soft'' phonon modes characterized by diminishing frequency as temperature approaches a critical point associated with symmetry breaking phase transition. While electron--soft coupling can introduce unique scattering channels for charge carriers in ferroelectrics, recent studies on the nonferroelectric lead halide perovskites have also sugges...