Volume 88, Issue 9, 01 November 2000
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS (PACS 42)
88(2000); http://dx.doi.org/10.1063/1.1315613View Description Hide Description
Electron-hole plasmaheating and ultrafast modulation in a semiconductor laser under a terahertz electrical field are investigated using a set of hydrodynamic equations derived from the semiconductor Bloch equations. The self-consistent treatment of lasing and heating processes leads to the prediction of a strong saturation and degradation of modulation depth even at moderate terahertz field intensity. This saturation places a severe limit to bandwidth achievable with such scheme in ultrafast modulation. Strategies for increasing modulation depth are discussed.
88(2000); http://dx.doi.org/10.1063/1.1314300View Description Hide Description
Photonicband structure analyses are applied to study the effect of slab thickness in two-dimensional photonic crystalslab waveguides. For transverse electric-like modes of a triangular lattice of air holes, the band gap of the asymmetric photonic crystal slab with a drilled low-index cladding do not differ significantly from that of the photonic crystal suspended in air over a wide range of slab thickness. The condition of single guided mode operation is also studied and it is found that the single mode cutoff thickness changes only by a small amount as an air-hole filling ratio varies once the center of the band gap is fixed.
88(2000); http://dx.doi.org/10.1063/1.1315325View Description Hide Description
Exact expressions are derived for the longitudinal and transverse polarizability of two overlapping conducting spheres of arbitrary radii and with arbitrary angle of intersection. The transverse polarizability is expressed as a single integral, which can be performed if the angle of intersection is a rational fraction of i.e., the angle of intersection can be expressed as with m and n integers. The longitudinal polarizability can be expressed as a single integral if the two spheres are equal. For unequal spheres it involves two integrals, as well as the capacity, which itself was expressed as a single integral earlier. For equal spheres the second integral vanishes by symmetry, and the capacity is not needed. Both integrals can be performed if the angle of intersection is a rational fraction of In earlier work by the authors the longitudinal and transverse polarizability were found only for discrete angles of intersection with n integer. Our result for the longitudinal polarizability of two equal overlapping conducting spheres shows that an earlier result of Radchik et al. [J. Appl. Phys. 76, 4827 (1994)] for overlapping dielectric spheres is incorrect.