Detuning (physics)

Upset

When detuning ( engl. Detuning ) is in the laser spectroscopy of a state of the laser with respect to the to be measured particles ( atoms , ions or molecules hereinafter), in which the frequency of the laser light is not resonant two with an atomic transition of energy levels of the particles. Colloquially this condition is called “ The laser is out of tune ”. ${\displaystyle \delta }$

Mathematically, the detuning is defined using the difference between the two angular frequencies :

${\displaystyle \delta =\omega _{L}-\omega _{A}={\frac {E_{L}-\Delta E}{\hbar }}}$

in which

• ${\displaystyle \omega _{A}}$ is the angular frequency of the atomic transition
• ${\displaystyle \omega _{L}}$ the angular frequency of the laser light
• ${\displaystyle \Delta E}$ the energy difference between the two energy levels
• ${\displaystyle E_{L}}$the energy of a photon from the laser
• ${\displaystyle \hbar }$the reduced quantum of action .

A distinction must be made between three cases:

• ${\displaystyle \delta <0}$- Red disgruntlement
• ${\displaystyle \delta =0}$ - Resonance, no upset
• ${\displaystyle \delta >0}$- Blue disgruntlement

The names red and blue detuning are derived from the electromagnetic spectrum . Red light has a lower frequency than blue light. However, this does not mean that out of tune laser light has one of these colors, but only indicates in which direction of the spectrum the frequency of the light is shifted.

The detuning has, among other things, a great influence on Rabi oscillations . It also plays a role in laser cooling .

Further information

Detuning is an important element of modern spectroscopic methods and is therefore dealt with in many textbooks in the corresponding fields of application.

• Wolfgang Demtröder: Laser Spectroscopy . 5th edition. Springer, Kaiserslautern 2007, ISBN 978-3-540-33792-8 .