Mechanical losses in thin fused silica fibres

Abstract

Intracavity topology of the readout system for LIGO III project and table-top QND mechanical measurements under development require the use of small probe masses and suspensions with a very low level of internal losses. A good choice is to use thin fused silica fibres similar to LIGO II mirrors suspensions. Mechanical losses of silica fibres are investigated in this work through the study of quality factor dependence on diameter for pendulum and violin modes of oscillations with diameters ranging from 1.5 to 40 µm. The estimated values of effective mechanical loss angle show noticeably greater growth with lower diameters than might be expected while extrapolating known results of research done for thicker fibres.