A vibration-insensitive optical cavity and absolute determination of its ultrahigh stability

We use the three-cornered-hat method to evaluate the absolute frequency stabilities of three different ultrastable reference cavities, one of which has a vibration-insensitive design that does not even require vibration isolation. An Nd: YAG laser and a diode laser are implemented as light sources. We observe similar to 1 Hz beat note linewidths between all three cavities. The measurement demonstrates that the vibration-insensitive cavity has a good frequency stability over the entire measurement time from 100 mu s to 200 s. An absolute, correlation-removed Allan deviation of 1.4 x 10(-15) at 1 s of this cavity is obtained, giving a frequency uncertainty of only 0.44 Hz. (C) 2009 Optical Society of Americ