Chen Weiyou

Effects of GaAs on Photoluminescence Properties of Self-Assembled InAs Quantum Dots

Room temperature photoluminescence (PL) spectra of InAs self-assembled quantum dots (QDs) deposited on a GaAs/InP and InP substrate are investigated. From the PL spectra, we find that the peak position of InAs QDs appears redshift from 0.795 to 0.785 eV after we insert a thin tensile GaAs layer between InAs QD layer and InP buffer layer. In order to explain this phenomenon in theory, we examine the strain tensor in InAs quantum dots by using a valence force field model and use a five-band kp formalism to obtain the electronic structure. The calculated results show that the ground transition energy decreases from 0.789 to 0.780 eV when the thin GaAs layer is inserted. Therefore, the PL peak position should appear redshift as shown in the experiment.

Parameter Optimization of a 9 × 9 Polymer Arrayed Waveguide Grating Multiplexer

Some important parameters are optimized for a 9?9 polymer arrayed waveguide grating multiplexer around the central wavelength of 1.55??m with the wavelength spacing of 1.6?nm. These parameters include the thickness and width of the guide core, diffraction order, pitch of adjacent waveguides, path length difference of adjacent arrayed waveguides, focal length of slab waveguides, free spectral range, the number of input/output channels and the number of arrayed waveguides. Finally, a schematic waveguide layout of this device is presented, which contains 2 slabs, 9 input and 9 output channels, and 91 arrayed waveguides.

Design of saturable absorber in colliding-pulse mode-locking quantum well laser diodes

Up to date the shortest semiconductor optical pulse has been generated by colliding-pulse mode-locking (CPM) multi-quantum well (MQW) laser diode. Symmetric three-segment structure containing saturable absorber (SA) is commonly used. Many pulse properties such as pulse width, spectra width, pulse energy, and timing-jitter have been studied in a great detail. As the design of devices structure is mentioned, little work is reported to our knowledge. In the paper we have investigated experimentally and theoretically the choice of lengths of absorber and gain sections affecting pulse properties.

Modeling of metal-semiconductor-metal photodetector

A complete model of Metal-Semiconductor-Metal Photodetector(MSM-PD) is presented. It can be used in any circuit simulators. Simulated DC characteristics for a GaAs MSM-PD are in good agreement with reported results.