Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 10 of 10
Full-Text Articles in Physical Sciences and Mathematics
Pump Dependence Of The Dynamics Of Quantum Dot Based Waveguide Absorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Pump Dependence Of The Dynamics Of Quantum Dot Based Waveguide Absorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
The nonlinear two stage recovery of quantum dot based reverse-biased waveguide absorbers is investigated experimentally and analytically as a function of the initial ground state occupation probability of the dot. The latter is controlled experimentally by the pump pulse power. The slow stage of the recovery is exponential and its basic timescale is independent of pump power. The fast stage of the recovery is a logistic function which we analyze in detail. The relative strength of slow to fast components is highlighted and the importance of higher order absorption processes at the highest pump level is demonstrated.
Mixed State Effects In Waveguide Electro-Absorbers Based On Quantum Dots, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Mixed State Effects In Waveguide Electro-Absorbers Based On Quantum Dots, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
Multi-pulse heterodyne pump-probe measurements are used to investigate the reverse bias dynamics of InAs/GaAs quantum dots in a waveguide structure. Using a femtosecond pulse, we simultaneously populate high energy ground states and low energy excited states and measure the resulting gain and phase dynamics over the bandwidth of the pulse. We identify a ∼5 ps timescale in the phase dynamics which can be associated with low energy ground states outside the pulse bandwidth and may provide an explanation for the deterioration of monolithic mode locked laser performance at high reverse voltages.
Induced Absorption Dynamics In Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Induced Absorption Dynamics In Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
Two-color pump-probe measurements are used to study the carrier dynamics of InAs/GaAs quantum dots in a waveguide structure under reverse bias conditions. For the case of initially populating the ground state (GS), we find relaxation dynamics that include both absorptive and bleaching components in the excited state (ES) wavelength range. We reproduce the main features of this induced absorption dynamics using a simple model with an additional term for induced absorption at the ES due to carriers injected at the GS. The induced absorption dynamics includes multiple recovery timescales which can be attributed to phonon-assisted processes of GS/ES interaction.
Refractive Index Dynamics Of Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Refractive Index Dynamics Of Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
The refractive index dynamics of InAs/GaAs quantum dot based waveguide absorbers is studied using heterodyne pump-probe measurements. Absorption reduction due to the pump can be accompanied by either positive or negative refractive index changes depending on the wavelength used. This change in sign of the phase amplitude coupling can be understood by considering the atomlike nature of the quantum dot transitions involved.
Recovery Time Scales In A Reversed-Biased Quantum Dot Absorber, T. Piwonski, Gillian Madden, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Recovery Time Scales In A Reversed-Biased Quantum Dot Absorber, T. Piwonski, Gillian Madden, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
The nonlinear recovery of quantum dot based reverse-biased waveguide absorbers is investigated both experimentally and analytically. We show that the recovery dynamics consists of a fast initial layer followed by a relatively slow decay. The fast recovery stage is completely determined by the intradot properties, while the slow stage depends on the escape from the dot to the wetting layer.
The Fast Recovery Dynamics Of A Quantum Dot Semiconductor Optical Amplifier, T. Piwonski, Guillaume Huyet, Et. Al.
The Fast Recovery Dynamics Of A Quantum Dot Semiconductor Optical Amplifier, T. Piwonski, Guillaume Huyet, Et. Al.
Physical Sciences Publications
We consider a rate equation model of a quantum dot semiconductor optical amplifier that takes into account carrier capture, escape, and Pauli blocking processes. We evaluate possible differences between phonon-assisted or Auger processes being dominant for recovery. An analytical solution which corresponds to phonon-assisted interaction is then used to accurately fit experimental recovery curves and allows an estimation of both the carrier capture and escape rates.
Intradot Dynamics Of Inas Quantum Dot Based Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Gillian Madden, Guillaume Huyet, Et. Al.
Intradot Dynamics Of Inas Quantum Dot Based Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Gillian Madden, Guillaume Huyet, Et. Al.
Physical Sciences Publications
The carrier relaxation and escape dynamics of InAs/GaAs quantum dot waveguide absorbers is studied using heterodyne pump-probe measurements. Under reverse bias conditions, we reveal differences in intradot relaxation dynamics, related to the initial population of the dots’ ground or excited states. These differences can be attributed to phonon-assisted or Auger processes being dominant for initially populated ground or excited states, respectively.
Phase Dynamics Of Inas/Gaas Quantum Dot Semiconductor Optical Amplifiers, T. Piwonski, Guillaume Huyet, Et. Al.
Phase Dynamics Of Inas/Gaas Quantum Dot Semiconductor Optical Amplifiers, T. Piwonski, Guillaume Huyet, Et. Al.
Physical Sciences Publications
The gain and phase dynamics of InAs∕GaAs quantum dot amplifiers are studied using single and two-color heterodyne pump probe spectroscopy. The relaxation of the wetting layer carrier density is shown to have a strong effect on the phase dynamics of both ground and excited state transients, while having a much weaker effect on the gain dynamics. In addition, the dynamical alpha factor may also display a constant value after an initial transient. Such behavior is strongly encouraging for reduced pattern effect operation in high speed optical networks.
Electron And Hole Dynamics Of Inas∕Gaasinas∕Gaas Quantum Dot Semiconductor Optical Amplifiers, I. O'Driscoll, T. Piwonski, C. F. Schleussner, J. Houlihan, G. Huyet, R. J. Manning
Electron And Hole Dynamics Of Inas∕Gaasinas∕Gaas Quantum Dot Semiconductor Optical Amplifiers, I. O'Driscoll, T. Piwonski, C. F. Schleussner, J. Houlihan, G. Huyet, R. J. Manning
Physical Sciences Publications
Single-color and two-color pump-probe measurements are used to analyze carrier dynamics in InAs∕GaAs quantum dot amplifiers. The study reveals that hole recovery and intradot electron relaxation occur on a picosecond time scale, while the electron capture time is on the order of 10ps. A longer time scale of hundreds of picoseconds is associated with carrier recovery in the wetting layer, similar to that observed in quantum well semiconductor amplifiers.
Carrier Capture Dynamics Of Inas/Gaas Quantum Dots, T. Piwonski, I. O'Driscoll, J. Houlihan, G. Huyet, R. J. Manning, A. V. Uskov
Carrier Capture Dynamics Of Inas/Gaas Quantum Dots, T. Piwonski, I. O'Driscoll, J. Houlihan, G. Huyet, R. J. Manning, A. V. Uskov
Physical Sciences Publications
Carrier dynamics of a 1.3μm InAs∕GaAs quantum dot amplifier is studied using heterodyne pump-probe spectroscopy. Measurements of the recovery times versus injection current reveal a power law behavior predicted by a quantum dot rate equation model. These results indicate that Auger processes dominate the carrier dynamics.