Vibration-insensitive
cutout cavity on its mount

The resonance frequency of a cavity used in an optical local oscillator is directly proportional to its length, and so dimensional stability is paramount. Vibrations lead to a change in the cavity length and consequently to frequency stability. Even when the cavity is supported on a vibration-isolation platform, performance is generally limited by vibrations.

Recently, we have developed a vibration insensitive optical cavity in order to overcome this limitation. Square 'cut-outs' are made to the underside of the cylindrical spacer, and the cavity is supported on four points.

By varying the separation of the supports, z, a null can be found in the vertical response to vibrations. At the response null, the sensitivity of the cut-out cavity to vertical vibrations is a factor of 1000 less than one of the conventional cylindrical design.

Experimental and theoretical response of the cavity to vertical vibrations