  Quantum noise limits the sensitivity of laser interferometric
gravitational-wave detectors. Given the state-of-the-art optics, the optical
losses define the lower bound of the best possible quantum-limited detector
sensitivity. In this work, we come up with a broadband signal recycling scheme
which gives potential solution to approaching this lower bound by converting
the signal recycling cavity to be a broadband signal amplifier using an active
optomechanical filter. We will show the difference and advantage of such a
scheme compared with the previous white light cavity scheme using the
optomechanical filter in [Phys.Rev.Lett.115.211104 (2015)]. The drawback is
that the new scheme is more susceptible to the thermal noise of the mechanical
oscillator.
