Temperature drift contribution to frequency instability of silicon Fabry - Perot cavities

A contribution of a temperature drift near the silicon thermal expansion coefficient zero point to the fractional frequency instability of a silicon cavity is analysed. The thermal expansion coefficient of silicon is measured by an optical method near the zero point T0 = 123 K. It is shown that the frequency instability due to cavity temperature drifts observed in an experiment does not exceed a thermal noise limit at averaging intervals of up to 20 s.