  We propose a new interferometer technique for high precision phase
measurements such as those in gravitational wave detection. The technique
utilizes a pair of optically coupled resonators that provides identical
resonance conditions for the upper as well the lower phase modulation signal
sidebands. This symmetry significantly reduces the noise spectral density in a
wide frequency band compared with single sideband recycling topologies of
current and planned gravitational wave detectors. Furthermore the application
of squeezed states of light becomes less demanding.
