title: Atomically thin nonreciprocal optical isolation.
abstract: Optical isolators will play a critical role in next-generation photonic circuits, but their on-chip integration requires miniaturization with suitable nonreciprocal photonic materials. Here, we theoretically demonstrate the thinnest possible and polarization-selective nonreciprocal isolation for circularly polarized waves by using graphene monolayer under an external magnetic field. The underlying mechanism is that graphene electron velocity can be largely different for the incident wave propagating in opposite directions at cyclotron frequency, making graphene highly conductive and reflective in one propagation direction while transparent in the opposite propagation direction under an external magnetic field. When some practical loss is introduced, nonreciprocal isolation with graphene monolayer still possesses good performance in a broad bandwidth. Our work shows the first study on the extreme limit of thickness for optical isolation and provides theoretical guidance in future practical applications.
authors.affiliation: 1] State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China [2] The Electromagnetics Academy at Zhejiang University, Zhejiang University, Hangzhou 310027, China [3] Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Xiao
authors.initials: X
authors.lastname: Lin
authors.affiliation: 1] State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China [2] The Electromagnetics Academy at Zhejiang University, Zhejiang University, Hangzhou 310027, China.
authors.forename: Zuojia
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.affiliation: 1] Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore [2] Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Baile
authors.initials: B
authors.lastname: Zhang
authors.affiliation: 1] State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China [2] The Electromagnetics Academy at Zhejiang University, Zhejiang University, Hangzhou 310027, China.
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Chen