Quantum interference and control of the dynamic Franz-Keldysh effect: Generation and detection of terahertz space-charge fields

Magneto-optical Franz-Keldysh effect of an electron gas subjected to quantizing magnetic fields and intense terahertz laser fields

Ultrafast and nonlinear spectroscopy of semiconductors with small energy photons

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...

Coherent Control of Quantum Entropy via Quantum Interference in a Four-Level Atomic System

The time evaluation of quantum entropy in a four-level double- type atomic system is theoretically investigated. Quantum entanglement of the atom and its spontaneous emission fields is then discussed via quantum entropy. It is found that the degree of entanglement can be increased by the quantum interference induced by spontaneous emission. The phase dependence of the atom-field entanglement is...

Resonant photodiffractive effect in semi - insulating multiple quantum wells

Received November 28, 1989; accepted April 10, 1990 We use semi-insulating multiple quantum wells to combine the holographic properties of the photorefractive effect with the large resonant optical nonlinearities of quantum-confined excitons. GaAs-AlGaAs multiplequantum-well structures are made semi-insulating by proton implantation. The implant damage produces defects that are available to tra...

Photorefractive quantum wells: transverse Franz-Keldysh geometry

The photorefractive properties of semi-insulating AlGaAs-GaAs multiple quantum wells are described for the transverse Franz-Keldysh geometry with the electric field in the plane of the quantum wells. Combining the strong electroabsorption of quantum-confined excitons with the high resistivity of semi-insulating quantum wells yields large nonlinear optical sensitivities. The photorefractive quan...