Feature Articles

Observation of the 0-fs pulse

The quest for the world's shortest laser pulse has led to a remarkable pace of development in ultrafast laser technology. Although pulses of only a few cycles duration have been made, clearly the observation of a 0-fs pulse would represent a key result in this field (see Fig. 1). In most experiments, a 100-fs pulse is amplified and passed through a nonlinear medium, generally a simple single-mode silica optical fiber. The resulting nonlinear propagation creates a large bandwidth increase, and, with careful control of subsequent optical phases, significant compression ratios have been obtained. A simple linear extrapolation predicted that continued progress should result in an important milestone (dashed line): the pulsewidth should have gone to zero in late 1986 and become negative in 1987. Incorporation of prisms have produced at best 6-fs (three-cycle) pulses.

by W.H. Knox, R.S. Knox, J.F. Hoose, and R.N. Zare
Looking at light sources

White light is made up of all the colors of the rainbow, but all white light does not contain the same mixture of the colors. You can see this when you look at the same colors under different lights. Some colors that look well matched in sunlight may not match under a fluorescent light, and may also look different under an ordinary incandescent bulb. Many people never notice the differences, but they are important enough that many photographic films are made specifically for either sunlight or light from manmade lamps.

by Jeff Hecht
Health issues top technology wish list

Results of a survey conducted last year by ISO show an international consensus of concern about health, safety, and the environment, with cancer detection and treatment viewed as the highest technological priority. About a year ago (May 1989, p. 46), I wrote a column about an ISO questionnaire that had been circulated to determine what kinds of new standardization work the organization should undertake. The questionnaire was divided into 10 topic areas from new materials to safety and the environment. Within each area, respondents were asked to assess the importance of developing the technology and when work should begin.

by Robert E. Parks
Prospects for SDI laser research

The Strategic Defense Initiative (SDI) is an aggressive program to research and develop a broad range of science and technologies for defense applications against ballistic missiles. A significant part of the program involves research related to lasers and optics. This article, in a pictorial format, summarizes some of the remarkable progress in this area and offers some insight into experiments, developments, and programs in progress. To understand the laser research programs and motivation for this work, it is useful to begin with a brief review of the overall SDI concept and defense architecture. The laser and optics application in these various architectures will be highlighted, and the progress and future directions of SDI laser and optics research will be discussed.

by O'Dean P. Judd