2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/211407We propose two detuned Fabry-Perot cavities, each pumped through both the mirrors, positioned in line as a toy model of the gravitational-wave (GW) detector free from displacement noise of the test masses. It is demonstrated that the noise of cavity mirrors can be completely excluded in a proper linear combination of the cavities output signals. This model is illustrated by a simplified round trip model (without Fabry-Perot cavities). We show that in low-frequency region the obtained displacement-noise-free response signal is stronger than the one of the interferometer recently proposed by S.Kawamura and Y.Chen.10 pages, 5 figuresGeneral Relativity and Quantum Cosmologytext