The Dick effect for an optical frequency standard

• Published in: Journal of optics. B, Quantum and semiclassical optics Vol. 5; no. 2; pp. S150 - S154
• Main Authors: Quessada, Audrey, Kovacich, Richard P, Courtillot, Irène, Clairon, André, Santarelli, Giorgio, Lemonde, Pierre
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bristol IOP Publishing 01.04.2003; Institute of Physics
• Subjects: Exact sciences and technology; Measurements common to several branches of physics and astronomy; Metrology, measurements and laboratory procedures; Physics; Sciences of the Universe; Time and frequency; Frequency standards; Laser noise; Optical frequency; Ramsey-Bordé interferometer; Frequency stability; Atomic clocks; optical frequency stability; low frequency noise laser; Optical frequency standard
• ISSN: 1464-4266; 1741-3575
• DOI: 10.1088/1464-4266/5/2/373

We present an analysis of the frequency stability degradation of an optical atomic frequency standard which is operated sequentially, and which is caused by the frequency noise of the laser used to interrogate the clock transition. This is an extension to optical frequencies of the 'Dick effect' already studied in atomic microwave frequency standards. It is shown that the simple concept of laser linewidth is not the relevant parameter to estimate the frequency stability degradation. Rather, the details of the laser frequency noise spectral density must be accounted for together with the parameters of the interrogation method. We compute the optical Dick effect in the case of a four pulse Ramsey-Borde interferometer. We show that it may be minimized by optimizing the time sequence so that only the Fourier frequencies with minimum laser noise are sampled. Finally, we evaluate the degradation which would be obtained with one of our lasers used as an interrogation oscillator. We show that with this particular laser, a relative frequency stability of the order of 10 exp -16 in a 1 s averaging time can be reached using realistic experimental parameters.