Influence Of Carrier Transport Research Articles

Influence of carrier transport on modulation characteristics of quantum-well semiconductor lasers

Influence of carrier transport on modulation characteristics of quantum-well semiconductor lasers

Influence of Carrier Transport on Diffraction Efficiency of Steady-State Photocarrier Grating

A two-dimensional theoretical model of a diffractive steady-state photocarrier grating (SSPCG) has been developed. The carrier diffusion equation with a spatially periodic excitation source was solved, and an analytical expression of the carrier density distribution was obtained. Based on the band-filling theory and the Kramers–Kronig relation, the carrier-induced refractive index change of SSPCG was estimated, and the refractive index profile was determined. The diffraction efficiency of the SSPCG was calculated by multilevel rigorous coupled-wave analysis. Simulations were carried out to investigate the influence of the carrier transport properties on the diffraction efficiency of the SSPCG. The results show that a semiconductor material with a longer lifetime and a smaller diffusivity will have a higher diffraction efficiency. The spatial amplitude of the carrier density and the grating strength of the SSPCG are closely related to the grating period. For an InP-based SSPCG, the diffraction efficiency of the $$+1\mathrm{st}$$ transmitted wave reaches its maximum value (25 %) when the grating provides a $$\pi $$ phase shift. The theoretical analysis and conclusions are helpful for material selection and experimental parameter determination of a diffractive SSPCG.

Influence of carrier transport on Raman amplification in silicon waveguides

This paper analyze for the first time the impact of the charge carrier transport on the continuously pumped stimulated Raman amplification in silicon waveguides. A novel analytical model is developed using which the coupled differential equations of the pump and the probe optical signals and those of carrier transport are solved concurrently. The simulation and analysis suggest that the neglect of the carrier transport phenomenon, reported in the previously published works, is approximately justified only if the effective carrier lifetime is comparable to the carrier transit time, otherwise it can result in substantial overestimation of the free carrier density at the optical mode center.

Electric-field-induced combination of Wannier-Stark localization and type-I–type-II crossover in a marginal type-I GaAs/AlAs superlattice

We have investigated the influence of carrier transport on photoluminescence (PL) properties in a marginal type-I GaAs/AlAs superlattice whose lowest X state ${(X}_{1})$ is situated in the lowest $\ensuremath{\Gamma}({\ensuremath{\Gamma}}_{1})$ miniband. By applying a bias voltage, the PL signal from the lower edge of the ${\ensuremath{\Gamma}}_{1}$ miniband disappears, while Stark ladder PL is observed from the ${X}_{1}$ state. With a further increase of the bias voltage, the PL signal from the X state disappears, while the PL signal from the ${\ensuremath{\Gamma}}_{1}$ state reappears as a Stark ladder transition. To confirm the electric-field dependence of the ${\ensuremath{\Gamma}}_{1}$- and ${X}_{1}$-related transition energies observed in the PL spectra, the corresponding electroreflectance spectra have been also measured. This PL property can be attributed to competitive carrier transport among the $\ensuremath{\Gamma}$ miniband, the localized $\ensuremath{\Gamma}$ Stark ladder states, and the ${X}_{1}$ state, which results in the transition between type-I and type-II radiative recombination processes.

Influence of carrier transport on performance of SLALOM with a polarization-independent MQW SLA

The switching performance of the semiconductor laser amplifier in a loop mirror (SLALOM) with a polarization-independent multiquantum-well SLA influenced by the carrier transport is discussed. It is shown that the switching window is polarization-dependent in the case of ultra-short pulses used as switching pulses because of the carrier transport effect between quantum wells. The influence of polarization can be suppressed by modifying the polarization state of local switching pulses.

Dynamic behavior of vertical-cavity surface-emitting lasers

A quasi-three-dimensional dynamic model of index-guided vertical-cavity surface-emitting lasers is developed. Detailed structure of Bragg reflectors and lateral optical confinement are considered into the model. A three-dimensional waveguide problem is reduced to one dimension by using the effective-index method. The dynamic response of optical field is solved by the time-domain algorithm. In addition, the lateral variation of carrier concentration, refractive index, and spontaneous-emission profile are also determined in a self consistent manner. Using this model, the influence of carrier transport and hot carriers on the dynamic behavior of vertical-cavity surface emitting lasers is studied. It is found that these nonlinearities have significant influence on the relaxation-oscillation frequency and modulation bandwidth of the devices.

The role of vertical transport and capture of electrons and holes for the transient optical response in quantum-well heterostructures

The transient optical response of quantum wells (QWs) after optical and electrical carrier injection into the barrier layers is studied experimentally and theoretically. We have varied the transport geometry in GaAs/AlGaAs and InGaAs/InAlGaAs heterostructures and emphasize the basic principles for a theoretical treatment of electron and hole capture into QWs for a proper description of vertical carrier transport in the barriers of QW heterostructures. Comparing our experimental data with the results of theoretical model calculations, we determine the capture, reflection and transmission probabilities, the ambipolar diffusivities and the ambipolar mobilities in the barriers of GaAs/AlGaAs, as a model system. The temporal evolution of the electron and the hole capture current densities at the QWs are studied in detail for a wide variation of the injected carrier densities. Amplitude modulation experiments are performed for InGaAs/InAlGaAs QW laser devices providing increasing 3 dB frequencies for decreasing confinement layer thickness, indicating the influence of carrier transport in the barriers.

Influence of carrier transport on wavelength chirp of InGaAs/InGaAsP MQW lasers

The effect of carrier transport across the heterostructure on wavelength chirp in 1.5 μm InGaAs/InGaAsP MQW lasers is described both theoretically and experimentally. A reduction in the FSK chirp to below the resolution limit of the measurements is observed together with an increased modulation bandwidth as the carrier transport time is reduced.