Natural Linewidth of the 401-nm Lasering-Cooling Transition in Erbium

Figure 1. Measurements of laser induced fluorescence on the 401-nm laser cooling line.
The ten data sets represent a series of different laser intensities, measured to examine the
contribution of power broadening. The solid red curves are the Lorentzian fits used to extract the linewidths.

In the process of studying our erbium magneto-optical trap, discrepancies between our observations and tabulated lifetime values led us to carry out a new measurement of the natural linewidth of the 4ƒ¹²6s^{2 3}H₆ → 4ƒ¹²(³H₆)6s 6p(¹P1^o) (6, 1)₇^o laser cooling transition at 401 nm. Using laser-induced fluorescence in a well-collimated erbium atomic beam, and measuring as a function of laser power to eliminate effects due to power broadening, we were able to obtain a value of

35.6 ± 1.2 MHz.

This value, which corresponds to a natural lifetime of 4.5 ns, differs significantly from the value of 27 MHz chosen for compilation in the NIST tables. This new, more accurate value will enable better understanding of laser cooling on this transition in future experiments.

Natural Linewidth of the 401-nm Laser-Cooling Transition in Er I

Jabez J. McClelland - NIST

Online: September 2006
Last Updated: February 2008

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