Measurement of Gouy phase evolution by use of spatial mode interference

An experimental technique to observe and accurately measure the Gouy phase evolution of Hermite–Gaussian modes is presented. Because of the unique features of spatial mode interference frequency-locking error signals, we are able to readily perform explicit measurement of the Gouy phase in a simple and highly accurate manner. We present these data and discuss the technique and its implications.This research was supported by the Australian Research Council as part of the Australian Consortium for Interferometric Gravitational Astronomy