Pan Aiqiang, Lin Kaixin, Chen Siru, Tso Chi Yan
School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China.
iScience. 2023 Jun 7;26(7):107032. doi: 10.1016/j.isci.2023.107032. eCollection 2023 Jul 21.
This study theoretically proved that although reciprocal optical devices can show asymmetric transmittivity (AT) under controlled incident modes (i.e., conditional AT), they cannot guarantee AT with arbitrary incident light modes, whereas only nonreciprocal optical devices can possibly guarantee AT. Besides, the thermodynamics of both reciprocal and nonreciprocal optical devices were discussed to show that the second law of thermodynamics is valid anyway. Furthermore, the diode-like behaviors of optical and electronic devices were compared. Electrons are identical to electronic devices, so electronic devices could have asymmetric conductance regardless of electrons. In contrast, electromagnetic waves are different from optical devices as transmittivity of different modes can be different, so reciprocal optical devices showing conditional AT cannot guarantee AT when incident modes are arbitrary. The mathematical proof and characteristic comparisons between electronic and optical diodes, which are firstly presented here, should help clarifying the necessary nonreciprocity required for being optical diodes.
本研究从理论上证明，尽管互易光学器件在受控入射模式下（即条件非对称透射率）可表现出非对称透射率（AT），但它们无法保证在任意入射光模式下都具有AT，而只有非互易光学器件才有可能保证AT。此外，还讨论了互易和非互易光学器件的热力学，以表明热力学第二定律无论如何都是有效的。此外，还比较了光学和电子器件的二极管样行为。电子与电子器件相同，因此电子器件无论电子如何都可能具有非对称电导。相比之下，电磁波与光学器件不同，因为不同模式的透射率可能不同，因此表现出条件AT的互易光学器件在入射模式为任意时无法保证AT。本文首次给出的电子和光学二极管之间的数学证明和特性比较，应有助于阐明成为光学二极管所需的必要非互易性。
