Observation of exceptional points in reconfigurable non-Hermitian vector-field holographic lattices

Recently, synthetic optical materials represented via non-Hermitian Hamiltonians have attracted significant attention because of their nonorthogonal eigensystems, enabling unidirectionality, nonreciprocity and unconventional beam dynamics. Such systems demand carefully configured complex optical pot...

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Published in:Nature communications 2016-07, Vol.7 (1), p.12201-12201, Article 12201
Main Authors: Hahn, Choloong, Choi, Youngsun, Yoon, Jae Woong, Song, Seok Ho, Oh, Cha Hwan, Berini, Pierre
Format: Article
Language:English
Subjects:
132/124
639/301/1019/482
639/624
639/766/400
Computer engineering
Eigenvectors
Humanities and Social Sciences
multidisciplinary
Optics
Physics
Polymers
Science
Science (multidisciplinary)
Symmetry
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Summary:Recently, synthetic optical materials represented via non-Hermitian Hamiltonians have attracted significant attention because of their nonorthogonal eigensystems, enabling unidirectionality, nonreciprocity and unconventional beam dynamics. Such systems demand carefully configured complex optical potentials to create skewed vector spaces with a desired metric distortion. In this paper, we report optically generated non-Hermitian photonic lattices with versatile control of real and imaginary sub-lattices. In the proposed method, such lattices are generated by vector-field holographic interference of two elliptically polarized pump beams on azobenzene-doped polymer thin films. We experimentally observe violation of Friedel’s law of diffraction, indicating the onset of complex lattice formation. We further create an exact parity-time symmetric lattice to demonstrate totally asymmetric diffraction at the spontaneous symmetry-breaking threshold, referred to as an exceptional point. On this basis, we provide the experimental demonstration of reconfigurable non-Hermitian photonic lattices in the optical domain and observe the purest exceptional point ever reported to date. Non-Hermitian Hamiltonians have attracted significant attention because of the unconventional wave-dynamic effects they allow. Here, Hahn et al . report reconfigurable non-Hermitian photonic lattices that permit versatile control of real and imaginary sub-lattices in the optical spectral domain.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms12201