Displacement transformer in laser gravitational-wave detectors

We analyze the measurement of small variations of distance between the mirrors of long Fabry–Perot cavity (model of gravitational wave detector) applying optical variant of displacement transformer. We show that using optical rigidity and manipulating the parameters of displacement transformer we can overcome Standard Quantum Limit (SQL) sensitivity without increasing laser pumping. The scheme analyzed has an additional potential of changing the shape of sensitivity curve over a wide range.