Table-top 0.001–1 Hz gravitational-wave detector: GRAVCOMB

The Laser Interferometer GravitationalWave Observatory (LIGO) made the first detection of gravitational waves (GWs) opening a new window on the Universe. LIGO sensesGWfrequencies from 5 to 1000 Hz. restricting its observations to a small fraction of cosmic GW events. The universe offers a rich set of astrophysical phenomena within the frequency range 0.001 to 5 Hz, whose observations will open independent measurements of the cosmic acceleration from Dark Energy, unique tests of General Relativity at cosmological scales, and new probes for physics beyond the Standard Model. This project is about evaluating the feasibility of a new GW detector, gravcomb, based on correlated optical combs, capable of detecting GW in the 0.001 to 5 Hz range. A phase resolution of 50 picoradian (corresponding to sensing a 10 attometer displacement) was demonstrated with a 2 m OPO. A 100 fold improvement is expected by miniaturizing the sensor in an integrated optics chip, and another 100times enhancement by coupling the OPO to a microring. To Measure GW strain, two OPO’s separated by meter distances are pumped by the same pump comb, so that the displacement they measure is with respect to a fixed refere