Speaker
Description
The sensitivity of current GW detectors, such as aLIGO, are critically reliant on the optimal operation of its system of coupled cavities. Unfortunately, the cavities’ resonant spatial eigenmodes and their control is affected by thermal deformations, allowing lossy higher order modes to build-up, whilst reducing the gain of control sidebands. Additionally, these deformations compromise the injection of squeezed light. Together, these effects limit the sensitivity of the detector and must be understood to achieve 1MW stored power in the future. Commissioning and optimization of the thermal compensation system is time-consuming and there are not yet sufficient actuators installed to fully counteract the thermal effects.
To study these limiting effects in more detail a bench-top, folded coupled cavity experiment is being constructed to investigate mirror heating and thermal actuation effects on higher order modes and audio sidebands. It consists of an arm cavity designed to replicate the LIGO thermal conditions using a suspended 98mm diameter ITM in vacuum, which is coupled to a recycling cavity. The cavities have been designed to replicate the Gouy phase accumulation observed in LIGO and a small-scale TCS will be installed. This presentation will describe the design of the coupled cavity and preliminary work towards its assembly.