Electron-beam propagation in a two-dimensional electron gas

A quantum mechanical model based on a Green's function approach has been used to calculate the transmission probability of electrons traversing a two-dimensional electron gas injected and detected via mode-selective quantum point contacts. Two-dimensional scattering potentials, back-scattering, and temperature effects were included in order to compare the calculated results with experimentally observed interference patterns. The results yield detailed information about the distribution, size, and the energetic height of the scattering potentials.Comment: 7 pages, 6 figure

Phase modulation parallel optical delay detector for microwave angle-of-arrival measurement with accuracy monitored

A novel phase modulation parallel optical delay detector is proposed for microwave angle-of-arrival (AOA) measurement with accuracy monitored by using only one dual-electrode Mach-Zenhder modulator. A theoretical model is built up to analyze the proposed system including measurement accuracy monitoring. The spatial delay measurement is translated into the phase shift between two replicas of a microwave signal. Thanks to the accuracy monitoring, the phase shifts from 5{\deg} to 165{\deg} are measured with less than 3.1{\deg} measurement error

Probing the potential landscape inside a two-dimensional electron-gas

We report direct observations of the scattering potentials in a two-dimensional electron-gas using electron-beam diffaction-experiments. The diffracting objects are local density-fluctuations caused by the spatial and charge-state distribution of the donors in the GaAs-(Al,Ga)As heterostructures. The scatterers can be manipulated externally by sample illumination, or by cooling the sample down under depleted conditions.Comment: 4 pages, 4 figure

Performance of a SOA-MZI wavelength converter for label swapping using combined FSK/IM modulation format

This paper presents a theoretical and experimental assessment of the performance of a wavelength converter based on semiconductor optical amplifiers (SOA) in a MZI configuration for optical label swapping. The optical labeling of the signal is based on an FSK/IM combined modulation format for the header/payload, respectively. Experimental results are presented for a signaling scheme with payload data at 10 Gbit/s and an FSK label at 312 Mbit/s. Simulation results and measurements of the chirp properties of converted signals operating at data rates of 2.5 and 10 Gbit/s are presented. Conclusions and design guidelines are presented regarding the implications of the wavelength converter performance on the quality of the label and payload signals for fast packet/burst forwarding in optically labeled switched networks

Optimisation of in-building optical networks

Abstract A single in-building optical fibre network can efficiently deliver wired and wireless services. Point-topoint architectures using POF are attractive for small buildings; for large buildings SMF-based all-optical bus architectures using weighted tap couplers are preferable