A Mesoscopic Blue-detuned Light Ring for Bose-Einstein Condensates Based on Conical Refraction

Abstract

Conical refraction (CR) is an optical phenomenon observed in biaxial crystals (BCs) that has been a subject of renewed interest since the last decade [1], despite being predicted by W.R. Hamilton in 1832. CR occurs when a light beam propagates along one of the optic axes of a biaxial crystal with birefringence R0 = l·α, where l is the length of the crystal and α is its conicity [2]. Under such conditions, an input focused Gaussian beam with beam waist radius w0, is transformed into two concentric bright rings at the focal image plane of the system, as long as the condition R0 >> w0 is satisfied. These bright rings are separated by a thin ring of null intensity known as the Poggendorff dark ring (PDR), see Fig. 1