  Motivated by the optical-bar scheme of Braginsky, Gorodetsky and Khalili, we
propose to add to a high power detuned signal-recycling interferometer a local
readout scheme which measures the motion of the arm-cavity front mirror. At low
frequencies this mirror moves together with the arm-cavity end mirror, under
the influence of gravitational waves. This scheme improves the low-frequency
quantum-noise-limited sensitivity of optical-spring interferometers
significantly and can be considered as a incorporation of the optical-bar
scheme into currently planned second-generation interferometers. On the other
hand it can be regarded as an extension of the optical bar scheme. Taking
compact-binary inspiral signals as an example, we illustrate how this scheme
can be used to improve the sensitivity of the planned Advanced LIGO
interferometer, in various scenarios, using a realistic classical-noise budget.
We also discuss how this scheme can be implemented in Advanced LIGO with
relative ease.
