We analyze the 1.5μm wavelength operation of a room temperature polarization switch based on electron spin dynamics in InGaAsP multiple quantum wells. An unexpected difference in response for left and right circularly polarized pump light in pump–probe measurements was discovered and determined to be caused by an excess carrier induced birefringence. Transient polarization rotation and ellipticity were measured as a function of time delay.

Time-resolved photoluminescence measurements of an undoped InGaAsP multiple-quantum-well heterostructure at excess carrier densities between 1014 and 1016 cm−3 reveal unexpectedly long carrier lifetimes, in excess of 2 μs. By fitting the appropriate rate equation parameters to our results, we establish that radiative recombination is the dominant relaxation process, and show that nonradiative recombination is much less pronounced than in similar quantum-well structures measured previously.

Excitonic optical nonlinearities are exploited in room temperature InGaAsP multiple quantum wells to determine the in-well carrier mobilities and spin relaxation processes. The picosecond time scale of the spin relaxation leads to the creation of a fast all-optical polarisation switch by using a circular polarised excite and a linear polarised probe pulse. It is demonstrated that the operation of the switch is dependent on the sense of circular polarisation of the probe. An optically induced birefringence is identified.

Summary form only given. We present transient amplitude and spin grating measurements in room temperature InGaAsP multiple quantum wells (MQWs) for the first time using picosecond laser pulses at 1.525 microns. We deduce in-well diffusion coefficients and compare these with those previously reported for GaAs.

Three-pulse transient amplitude grating experiments were performed using picosecond pulses at 1.525 /spl mu/m on room-temperature InGaAsP multiple quantum wells using a periodically poled LiNbO/sub 3/ (PPLN) optical parametric oscillator. An ambipolar diffusion coefficient of 7.2 cm/sup 2//s was measured from the diffraction efficiency decay rates. We deduce the presence of alloy scattering or an increase in interface scattering when comparing these results with those of similar experiments on GaAs-AlGaAs multiple quantum wells.

Summary form only given. Unexpectedly long lifetime circular dichroism has been observed in InGaAsP multiple quantum wells (MQW) at room temperature after creation of spin-polarized electrons. This has been investigated using the pump-probe technique with circularly polarized pump and linearly polarized probe pulses. We observe signals of opposite sign when using left or right circular polarization. We investigate this by measuring the rotation and ellipticity of the probe pulse train.

Summary form only given. We have performed amplitude and spin gratings on room temperature InGaAsP multiple quantum wells at 1.52 /spl mu/m. We present our results for the spin grating using a mathematical model taking into account the spin relaxation and electron diffusion. Polarization gratings are produced when two pulses with crossed linear polarization intersect. A periodic modulation of the electric field polarization and circular polarization occurs across the excitation region. Resonance with the heavy hole exciton creates an electron spin grating because of the interband selection rules. This will decay with a rate determined by a combination of the spin relaxation rate and the diffusion of the carriers within the quantum wells.