A theoretical approach to thermal noise caused by an inhomogeneously distributed loss -- Physical insight by the advanced modal expansion

摘要

We modified the modal expansion, which is the traditional method used tocalculate thermal noise. This advanced modal expansion provides physicalinsight about the discrepancy between the actual thermal noise caused byinhomogeneously distributed loss and the traditional modal expansion. Thisdiscrepancy comes from correlations between the thermal fluctuations of theresonant modes. The thermal noise spectra estimated by the advanced modalexpansion are consistent with the results of measurements of thermalfluctuations caused by inhomogeneous losses.