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.

© 2015 IEEE