Peter N. Saeta

How much can guided modes enhance absorption in thin solar cells

Absorption enhancement in thin metal-backed solar cells caused by dipole scatterers embedded in the absorbing layer is studied using a semi-analytical approach. The method accounts for changes in the radiation rate produced by layers above and below the dipole, and treats incoherently the subsequent scattering of light in guided modes from other dipoles. We find large absorption enhancements for strongly coupled dipoles, exceeding the ergodic limit in some configurations involving lossless dipoles. An antireflection-coated 100-nm layer of a- Si:H on Ag absorbs up to 87% of incident above-gap light. Thin layers of both strong and weak absorbers show similar strongly enhanced absorption.

Distinguishing surface and bulk contributions to third-harmonic generation in silicon

We report measurements of third-harmonic generation from ultrathin crystalline silicon layers of gradually varying thickness. Both the angular and thickness dependence of the third-harmonic light generated in transmission at normal incidence are consistent with negligible surface contribution to third-harmonic generation in silicon, even under tight focusing. This work illustrates a method for distinguishing surface and bulk contributions to harmonic generation.

Using WebQuiz and the college intranet to enhance class time and support independent investigation

Describes how online assignments using the WebQuiz program developed at Harvey Mudd College enrich both technical and non‐technical courses in several important ways. By helping prepare students for class by encouraging careful reading of background material, the focus of class time can shift from exposition to development of ideas, leading to a richer and more interactive classroom experience. By providing guidance and detailed feedback, WebQuiz can be used to support students in their independent review of material, as well as in the independent study of new material. Discusses in detail several applications of this flexible, Web‐based platform.

Ultrafast dynamics of periodic arrays of holes in a gold film

We show that the enhanced transmission of gold nanostructures made of arrays of holes exhibits two kinds of resonances. Their spectral position and line-width strongly depend on the electron dynamics induced by femtosecond optical pulses.

Femtosecond dynamics of light transmission through sub-wavelength hole arrays in metallic films

We report on the observation of an ultrafast modification of /spl sim/30% in the enhanced transmission through sub-wavelength nanometric apertures in metallic films. It demonstrates the feasibility of nanoscaled femtosecond optical switches.

Women in Physics in the United States

The underrepresentation of women in physics and related fields in the US remains significant despite an increase in doctoral degrees earned over the past 10 years. An even greater disparity is seen among minority women. Increasing recognition of the contributions of women to discovery and education in physics and related fields has led to government initiatives and other programs to promote broader inclusion, balance, and gender equity. These actions for advocating women in physics in the US since the first IUPAP Women in Physics Conference in 2002 are presented.

Topic 1: Attracting Girls Into Physics

We discuss the problems in attracting girls into physics. We present some of the projects undertaken in various countries to ameliorate the problem, and we conclude with some follow‐up suggestions that can be implemented in all countries.