Zhaoyang Zhang1、7、*, Yuan Feng1, Shaohuan Ning1, G. Malpuech2, D. D. Solnyshkov2、3、8、*, Zhongfeng Xu4, Yanpeng Zhang1, and Min Xiao5、6
Author Affiliations
1Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Laboratory of Information Photonic Technique, School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China2Institut Pascal, PHOTON-N2, Université Clermont Auvergne, CNRS, SIGMA Clermont, F-63000 Clermont-Ferrand, France3Institut Universitaire de France (IUF), F-75231 Paris, France4Department of Applied Physics, School of Science, Xi’an Jiaotong University, Xi’an 710049, China5Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA6National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China7e-mail: zhyzhang@xjtu.edu.cn8e-mail: dmitry.solnyshkov@uca.frshow less
Fig. 1. (a) Experimental setup. Three coupling beams, E2, E2′, and E2′′, from the same laser source intersect inside the vapor cell to establish a hexagonal interference pattern acting as the coupling field Ec. The angle between any two of the coupling beams is 2 θ≈0.4 deg. The focal length of the imaging lens is 200 mm, and the distance between the lens and the CCD camera is 400 mm. (b) The energy-level configuration driven by the probe and coupling fields; (c) projection of the four beams (before entering the cell) on the x−y plane; calculated susceptibility at (d), (e) Δ1=−60 MHz and (f), (g) Δ1=−110 MHz with Δ2=−100 MHz, respectively.
Fig. 2. Numerical simulations of a complex honeycomb photonic lattice. (a) Dispersion in the Hermitian case showing the lowest bands (s and mixed p/d band); (b) dispersion in the non-Hermitian case with the maximal intensity coming from the lowest-decay state at the Γ point of the p/d band; (c), (d) spatial profiles of the Γ states of the s and p/d bands, responsible for the lattice switching. Here, a and a* are the direct and reciprocal lattice constants.
Fig. 3. Output probe patterns at different probe detunings. (a) Experimentally established coupling field; (b) observed discretized probe beam at different Δ1 with a fixed Δ2=−100 MHz. The corresponding simulations are shown in (c).
Fig. 4. Observed self-imaging effect of the output probe beam at different probe detunings. (a) Δ1=−90 MHz and (b) Δ1=−110 MHz.
Fig. 5. PT-symmetric-like transition measured by the symmetry factor as a function of the relative non-Hermiticity controlled by the detuning; black solid line, square root scaling; black dots, numerical simulations; red dots, experiment (error bars indicate the uncertainty).