The sign of the chirality per unit energy of a HE or EH mode is the same as or opposite to, respectively, the sign of the phase circulation direction. When the fiber radius is large enough, the field in a quasicircularly polarized hybrid mode can be superchiral outside the fiber. In particular, outside a fiber with a radius of 600 nm, the fields in the quasicircularly polarized HE11, HE21, and HE31 modes are superchiral. | Communications in Physics, Vol. 27, No. 1 (2017), pp. 23-35 DOI: Invited Paper CHIRALITY OF LIGHT IN HYBRID MODES OF VACUUM-CLAD ULTRATHIN OPTICAL FIBERS ´ NIC CHORMAIC3,4 FAM LE KIEN1,† , TH. BUSCH2 , VIET GIANG TRUONG3 and SILE 1 Quantum Systems Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan 2 Quantum Systems Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan 3 Light-Matter Interactions Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan 4 School of Chemistry and Physics, University of KwaZulu-Natal, Durban, KwaZulu-Natal, 4001, South Africa † E-mail: kien pham@ Received 21 February 2017 Accepted for publication 9 March 2017 Abstract. We investigate chirality of light in the quasicircularly polarized fundamental and higherorder hybrid modes of vacuum-clad ultrathin optical fibers. We show that, for a given fiber with the parameters in the range of experimental interest, the higher-order modes have smaller optical chirality per unit energy than the fundamental mode. The sign of the chirality per unit energy of a HE or EH mode is the same as or opposite to, respectively, the sign of the phase circulation direction. When the fiber radius is large enough, the field in a quasicircularly polarized hybrid mode can be superchiral outside the fiber. In particular, outside a fiber with a radius of 600 nm, the fields in the quasicircularly polarized HE11 , HE21 , and HE31 modes are superchiral. Keywords: chirality, higher orders, hybrid modes, ultrathin optical fibers. Classification numbers: , , . I. INTRODUCTION Guided fields of vacuum-clad ultrathin optical fibers [1–3] penetrate deeply into the surrounding medium and appear as an evanescent wave carrying a significant fraction of the power c 2017 Vietnam Academy of Science and .
