Fig. 3: Variable ellipticity of resonant modes generated in Möbius-strip cavities.
From: Experimental observation of Berry phases in optical Möbius-strip microcavities
a, Linearly polarized light propagating along a twisted strip leads to the existence of in-plane and out-of-plane components and the formation of an elliptical polarization state. b, Cross-sectional views of the electric-field amplitude distributions for T/W = 0.67. Insets: magnified images of the electric field at the vertical and horizontal sites. Arrows indicate the local polarization. c, Polarization-resolved measurements for Möbius strips with T/W = 0.33 and 0.67. Dots, measured data; lines, sinusoidal fits. d, Summarized light ellipticity extracted from the simulated modes at the horizontal site of Möbius strips as a function of T/W. e, For simplicity, a cyclic evolution of the polarization state vector on a Poincaré sphere is used to describe the optical resonances in the Möbius strip, indicating that the occurring Berry phase directly depends on the ellipticity (represented by lines with arrows).
