We track the dynamic response of GaAs quantum-well semiconductor diode lasers after injection of a femtosecond pulse, using ultrafast upconversion. The continuous-wave emission shows gain dynamics and relaxation oscillations on timescales of 1–100 ps. The recirculating femtosecond pulse evolves into an ultrafast ‘‘dark pulse’’ in the wake of subpicosecond oscillations. © 1998 American Institute...

Abstruct-The term ‘T-rays’ was coined era1 advantages over single frequency methods in the early 1990’s by Bell Labs to deincluding interfering background signal eliminascribe the spectrum in the TeraHertz range tion and simultaneous acquisition of many fre(1 THz= 10l2 Hz). The THz region of the spectrum lies on the border of where electronics and optics meet, between the mm-wave and infrared b...

Photoluminescence studies of neutral and charged excitons in modulation doped GaAs/Al0.3Ga0.7As quantum wells are performed as functions of applied pressure, temperature, and excitation power and frequency. Varying both pressure and incident power allows sensitive selection of the different exciton transitions. The G±X crossover in the barriers at 7 to 9 kbar accelerates photo-pumping of electr...

We propose a scheme for electrical measurement of two-electron spin states in a semiconductor double quantum dot. We calculated the adiabatic charge transfer when surface gates are modulated in time. Because of spin-orbit coupling in the semiconductor, spatial displacement of the electrons causes a total spin rotation. It follows that the expectation value of the transferred charge reflects the...

We propose a compact high-intensity room-temperature source of entangled photons based on the efficient second-order process of two-photon spontaneous emission from electrically pumped semiconductor quantum wells in a photonic microcavity. Two-photon emission rate in room-temperature semiconductor devices is determined solely by the carrier density, regardless of the residual one-photon emissio...

The temperature dependence of below-threshold emission from multiple quantum well semiconductor lasers is well characterized by a power law, in excellent agreement with Landau-Ginzburg theory of second-order phase transitions. We thereby show that it is the temperature dependence of net gain and not that of nonradiative recombination which primarily determines temperature sensitivity of thresho...