2011 – Munushian Lecture

Dr. John Hall
“The Optical Frequency Comb – a new tool with remarkable applications in Science, Metrology, and Medical Diagnostics”

Lecture Abstract
We easily accept the remarkable capabilities available in the Radio Frequency domain: cellphones, HiDef TV, wireless computer connections, bluetooth earphones, etc. Optical frequency waves represent the same physics as their RF siblings, but oscillate at some million-fold faster rates. So there is correspondingly more bandwidth for signals and interesting new processing ideas but, until recently, there were no optical tools with precision capabilities that even remotely approached a similar level. The avalanche of progress began in 1999 when a group at Lucent Labs demonstrated that a special type of optical fiber could give a highly nonlinear response, converting input laser wavelengths into rainbow light across the visible spectrum, and in a coherent manner. Within a few months two separate laboratories had seen the connections of three independent streams of research, and merged these “ obviously unrelated” fields to create a new tool, the Optical Frequency Comb, a new kind of laser light with remarkable properties. Only six years later the Nobel Prize was awarded for these advances. One dramatic application is the precision testing of some fundamental & basic assumptions about physical reality: spatial symmetry and uniformity, constancy of the speed of light, and stability of the physical “constants” in our equations. Second is an exciting Medical Diagnostic application which analyzes exhaled human breath for marker molecules associated with diseases such as diabetes, asthma, cancer, and renal failure. It is important that the sensitivity is so great that sub-clinical molecular concentrations can be measured in apparently healthy subjects. For example, Carbon Monoxide was measurable only in the breath of one student — a former smoker who had quit almost one year previously!

Dr. John L Hall’s credits include a number of major innovations and developments in laser frequency stabilization, high resolution and ultrasensitive laser spectroscopy, laser length and frequency standards, laser/atom cooling, quantum optics and high-precision laser-based measurements. Author of more than 230 articles in refereed journals, he also holds 11 U. S. patents, the most recent on “ Airport Sniffing.” He is a member of the National Academy of Sciences, and of the French Légion d’ honneur, Senior Fellow Emeritus of the National Institute of Standards and Technology (NIST), and Fellow of the Optical Society of America and the American Physical Society. He was awarded the 2005 Nobel Prize in Physics, jointly with Prof. Hänsch of Munich and Prof. Glauber of Harvard.