In photonics and optics, the refractive index of a material, first introduced by Isaac Newton as the optical density, is the most fundamental material constant. Since the refractive index determines refraction and reflection occurring at the boundary between two media, it is a critical parameter for the design of optical components, such as distributed Bragg reflectors (DBRs), omnidirectional r...

The deposits of Eocene Lake Gosiute that constitute the Green River Formation of Wyoming contain numerous tuff beds that represent isochronous, correlatable stratigraphic markers. Tuff beds selected for 40Ar/39Ar analysis occur within laminated mudstone, are matrix supported, and lack evidence of reworking. These tuffs contain 2%–15% euhedral phenocrysts of quartz, plagioclase, sanidine, biotit...

The deposits of Eocene Lake Gosiute that constitute the Green River Formation of Wyoming contain numerous tuff beds that represent isochronous, correlatable stratigraphic markers. Tuff beds selected for Ar/Ar analysis occur within laminated mudstone, are matrix supported, and lack evidence of reworking. These tuffs contain 2%–15% euhedral phenocrysts of quartz, plagioclase, sanidine, biotite, a...

A vapor–liquid–solid (VLS) growth of microwhiskers was developed by Wagner et al. in the 1960s. The recent re-examination of this method by the groups of Lieber, Yang, Samuelson, Wang, and others has resulted in the flourishing research into nanowires (NWs). Nearly all the IV, II– VI, III–V, and IV–VI semiconductor NWs can be synthesized. Ternary compound semiconductors have also been demonstra...

Numerical simulations on the evolution of stepscrew and edge-screw optical phase dislocations in bulk saturable self-defocusing nonlinear media are presented, with emphasis on their ability to induce steering waveguides for signal beams (pulses). Two schemes for directional coupling of such signals, both ensuring a reasonable coupling-to-crosstalk efficiency ratio, are investigated. The paramet...

It is well known that chirped (aperiodic) refractiveindex Bragg gratings can be used for compensating for the dispersion of optical fiber waveguides.' When used in reflection mode (in contrast to transmission mode), such Bragg gratings exhibit large dispersion. As well, the sign of the dispersion in reflection mode is easily controlled. Together these two characteristics suggest the use of chir...

High-resolution spectrographs for very large telescopes lead to new challenges in grating technology to achieve optimum matching of the slit width to the seeing disc. This has led elsewhere to the development of long echelles of high blaze angle produced by mosaicking technology. An alternative approach, pursued in this paper and adopted for the Gemini HighResolution Optical Spectrograph, is to...