Optical interferometers with reduced sensitivity to thermal noise

A fundamental limit to the sensitivity of optical interferometry is thermal noise that drives fluctuations in the positions of the surfaces of the interferometer's mirrors, and thereby in the phase of the intracavity field. Schemes for reducing this thermally driven phase noise are presented that rely upon the coherent character of the underlying displacements and strains. Although the position of the physical surface fluctuates, the optical phase upon reflection can have reduced sensitivity to this motion. While practical implementation of such schemes for coherent compensation face certain challenges, we hope to stimulate further work on this important thermal noise problem.