Volume 91, Issue 10, 15 May 2002
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS (PACS 42)
91(2002); http://dx.doi.org/10.1063/1.1467404View Description Hide Description
Gain quenched lasers can satisfy the requirements for all-optical switches in communications and computing systems. Hitherto, these devices have lacked optical gain between the input beam and output beam, and have been limited to switching amplitude modulated optical signals. A simple model based on the laser rate equations demonstrates that quenched devices can convert wavelength modulated signals into amplitude modulated ones with programmable optical gain. The discussion includes the effect of carrier injection, laser construction, and type of heterostructure.
91(2002); http://dx.doi.org/10.1063/1.1469664View Description Hide Description
The effects of nitrogen on GaAsP light-emitting diodesgrown by hydride vapor phase epitaxy are described. Nitrogen acts as an isoelectronic trap and this localized state makes GaAsP a widely used material for from-yellow-to-red visible light-emitting diodes. The photoluminescence and electroluminescencespectra,brightness, and reliability were investigated systematically in line with the function of nitrogen concentration, from 0 (without nitrogen) to When the nitrogen concentration reached the total emission in the photoluminescencespectrum at 4.2 K showed a redshift. The study provides clarification of the effects of nitrogen on the diodes and demonstrates that the characteristics of the diodes strongly depend on the nitrogen concentration.
91(2002); http://dx.doi.org/10.1063/1.1473677View Description Hide Description
An efficient and versatile many-body nonequilibrium approach is formulated for computation of photocurrent and photoexcited properties of device structures where quantum effects dominate. This method, based on nonequilibrium Green’s functionquantum transport equations, makes it possible to consider open systems of arbitrary dimensionality having complex potentials, complex geometries, and multiple terminals. In contrast to other approximate computational approaches, no a priori assumptions regarding the particular nature of the phototransitions are required (i.e., bound-to-bound, bound-to-continuum, or continuum-to-continuum). Furthermore, if desired, electron–phonon and electron–electron interactions can also be rigorously accounted for within the same formalism. In this article, the method is applied to two typical resonant-tunneling infrared detector heterostructures as examples: (1) a single-quantum-well structure, and (2) a multiperiod superlattice structure.