Impact and Mitigation of Wavefront Distortions in Precision Interferometry

Ultra-stable laser interferometry has become a cornerstone of precision metrology. Understanding higher-order optical modes is of particular interest to the Laser Interferometric Gravitational Wave (GW) detection community. Recent research at detectors shows that mode mismatches account for a significant amount of the squeezing loss, which reduces the range of the detector.

The aim of this project is to investigate a novel technique which directly access the mode structure of a laser beam. We will improve the dynamic range of the technique, characterise the design tradeoff's and determine predominant noise sources across the frequency range relevant to GW detection. Such a device could be used during the commissioning of precision metrology devices to improve signal to noise of the setup, in the case of LIGO this can improve the detection rate and signal to noise ratio of high frequency sources such as Binary Neutron Stars.

Optical Clocks and GW detectors share a common limiting noise source, mirror coating brownian noise. By switching the interrogation light to a higher order spatial mode, this may be reduced. We will investigate losses in this technique and find that the sensitive to mismatches increases. The mode analyser technique we investigate will provide valuable insight into the beam and mismatches. This technique may become an enabling technology for charting brownian noise reduction in optical clocks and GW detectors.