Measurements of the geometric phase of first-order optical Gaussian beams

Abstract

Geometric phase is ubiquitous in systems that undergo cyclic transformations in either parameter or state space. Manifestations of this phase have been found in many physical systems. In optics, geometric phase has had an important effect, enhancing the way optical systems are analyzed, and stimulating the discovery of interesting effects and new applications. Two well-investigated manifestations of geometric phase in optics are the coiled optics phase, produced by sending an optical beam in a three-dimensional (coiled) path; and Pancharatnam phase, produced by changes in the state of polarization. A third phase, produced by transformations in the phase structure or mode of a Gaussian beam, has just begun to be explored [1]. High-order Gaussian beams have received much attention in the last few years due to their ability to carry orbital angular momentum [2]. Previous experimental investigations of this phase have been done in the microwave regime [3,4]. Here we present the first measurements of this geometric phase in the optical regime.