A high stability optical frequency reference based on thermal calcium atoms
Richard W. Fox, Jeffrey A. Sherman, W. Douglas, Judith B. Olson, Andrew D. Ludlow, Christopher W. Oates
Here we report an imprecision below 10-14 with a simple, compact optical frequency standard based upon thermal calcium atoms. Using a Ramsey-Borde spectrometer we excite features with linewidths 1S0-3P1 intercombination line at 657 nm. We have measured a fractional frequency instability below 6 x 10-15 at 1 s, with good prospects for still quieter performance. The key remaining issue is for this standard is how well first- and second-order Doppler drifts can be suppressed. Due to its experimental simplicity such a system could find application as a high stability reference for commercial applications.
Proceedings of 2012 IEEE Frequency Control Symposium