Volume 92, Issue 2, 15 July 2002
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS (PACS 42)
92(2002); http://dx.doi.org/10.1063/1.1486055View Description Hide Description
Amorphous silicon was made by ion irradiation of crystalline silicon with Xe ions at 77 K in the 1–4 MeV energy range. Thermal relaxation of the amorphous network at 500 °C for 1 h leads to an amorphous layer with a refractive index of significantly higher than that of crystalline silicon at can thus serve as a waveguide core in Si based optical waveguides.Channel waveguides were made by anisotropicetching of a 1.5 μm silicon-on-insulator structure that was partly amorphized. Transmission measurements of these waveguides as function of the amorphous silicon length show that the part of the waveguides exhibit a modal propagation loss of and a bulk propagation loss of Losses due to sidewall roughness are estimated, and are negligible compared to the modal loss.
92(2002); http://dx.doi.org/10.1063/1.1481965View Description Hide Description
The two-dimensional monopole mode is investigated as a candidate for a nondegenerate photonic band-gap(PBG) cavity mode. This monopole mode formed in a single defect triangular PBG cavity is truly nondegenerate and remains nondegenerate in the sense that the introduction of asymmetry does not result in splitting of the mode. Several methods to tune the resonant frequency of the mode are studied. The radii, positions, and shapes of the nearest-neighbor air holes are varied in this analysis using the three-dimensional finite-difference time-domain calculation. The quality factor of the monopole mode formed in a slab waveguide structure is found to be larger than that of the dipole mode when the shape of the nearest-neighbor holes is elliptical.
Improved light extraction from emitters in high refractive index materials using solid immersion lenses92(2002); http://dx.doi.org/10.1063/1.1487913View Description Hide Description
Solid immersion lenses (SILs) are optically transparent, truncated spheres, brought in contact with a sample to be imaged. The combination of a conventional optical microscope and a SIL results in a highly effective numerical aperture of the imaging system that can improve the resolution. In addition, when imaging high refractive index samples, such as semiconductors, the light collection efficiency can be increased drastically. We investigate the collection efficiency as a function of the SILs geometry and refractive index, using an analytical expression for the light dispersion through an arbitrarily truncated sphere. The theoretical results are compared to experimental measurements obtained on single quantum dots and are found to be in good agreement.