Laserbased Precision Spectroscopy

1
Laser-based Precision Spectroscopy

• Optical frequency comb techniques

2
Nobel prize

• Second part of the Nobel Prize in Physics jointly
  to
• John L. Hall
• JILA, University of Colorado and National
  Institute of Standards and Technology, Boulder,
  CO, USA and
• Theodor W. Hänsch
• Max-Planck-Institut für Quantenoptik,
  Garching and Ludwig Maximilians-Universität,
  Munich, Germany
• for their contributions to the development of
  laser-based precision spectroscopy, including the
  optical frequency comb technique.

3
Improved Precision in Measuring

• Investigate constants of nature
• Definition of a meter
• Michelson Morley

4
Comb Technique

• Measure an unknown frequency by relating it to
  one of the frequencies in the comb
• Hänsch demonstrated frequency marks are evenly
  distributed
• 5 fs pulse requires locking a million modes ?
  need media with broad gain profile (dyes,
  titanium-doped sapphire)

5
Pulsed Laser
6
Frequency Comb
7
Pulses in phase
8
Pulses not in phase
9
Determining the off-set
10
Results

• Precision of optical laser spectroscopy similar
  to microwave atomic clocks at the femtosecond
  level
• In the future, all-optical clocks might approach
  a precision at the attosecond level