Theodor W. Hänsch: 2005 - Physics

Theodor Hänsch
Theodor Hänsch

Year & Category

2005 Nobel Prize in Physics (jointly with the American John L. Hall; they shared the divided Prize with the American Roy J. Glauber who was honoured “for his contribution to the quantum theory of optical coherence”)

Prize motivation

“For their contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique”

At the time of the award he worked at

Max-Planck-Institut für Quantenoptik, Garching, Germany, Ludwig-Maximilians- Universität, Munich, Germany

About his research

Revolutionary optical clock
Precision spectroscopy is used to measure optical frequencies and enables the extremely exact determination of physical constants – in other words, the fundamentals of physics. At the Max Planck Institute of Quantum Optics Theodor Hänsch built a measuring instrument offering an unprecedented level of precision: an optical clock. Such a clock measures the oscillations in the electromagnetic field of visible light. That is roughly 10¹⁵ oscillations per second. A pulse laser is used to “measure” the light. The frequency spectrum of the pulse laser resembles a comb whose teeth represent the measured frequencies, hence the name frequency comb.

Diverse applications
This comb enabled the measurement of light frequencies to an accuracy that had never been possible before. The practical applications for the frequency comb technique are diverse. For example, it has enabled the development of optical atomic clocks that can measure time up to 100,000 times more accurately than the best conventional clocks. These new clocks can also help to improve the performance of satellite navigation systems and increase data transmission rates in glass-fibre networks.