Super-broadband geometric phase devices based on circular polarization converter with mirror symmetry

• Published in: Applied physics letters Vol. 119; no. 10
• Main Authors: Chen, Wan, Yu, Yang, Mu, Quanquan, Campos, Juan, Wang, Qidong, Li, Shixiao, Zhang, Shiyuan, Xuan, Li
• Format: Journal Article
• Language: English
• Published: 06.09.2021
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0060647

We propose a simple implementation to obtain super-broadband geometric phase devices (GPD) by means of circular polarization converter (CPC) with mirror symmetry. We demonstrate that the best choice of wideband GPDs and CPCs is a mirror symmetric structure. Based on a two-rotation model on the Poincaré sphere, optimization parameters and time are significantly reduced. The CPC can be extended to super-broadband GPD, such as polarization gratings (PGs), by using geometric phase holography. We simulate diffraction efficiencies of the super-broadband PGs. In the normal incident case, the diffraction efficiency is over 99% in 420–945 nm, and in the oblique incident case, the first-order diffraction efficiency is over 90% in the range of ±30°. The super-broadband GPDs show potential advantages in wide color display and spectral imaging.