| [1] | Haldane, F. D. M. & Raghu, S. Possible realization of directional optical waveguides in photonic crystals with broken time-reversal symmetry. Phys. Rev. Lett. 100, 013904 (2008). doi: 10.1103/PhysRevLett.100.013904 | 
| [2] | Wang, Z., Chong, Y., Joannopoulos, J. D. & Soljačić, M. Observation of unidirectional backscattering-immune topological electromagnetic states. Nature 461, 772-775 (2009). doi: 10.1038/nature08293 | 
| [3] | Rechtsman, M. C. et al. Photonic Floquet topological insulators. Nature 496, 196-200 (2013). doi: 10.1038/nature12066 | 
| [4] | Khanikaev, A. B. et al. Photonic topological insulators. Nat. Mater. 12, 233-239 (2013). doi: 10.1038/nmat3520 | 
| [5] | Hafezi, M., Mittal, S., Fan, J., Migdall, A. & Taylor, J. M. Imaging topological edge states in silicon photonics. Nat. Photon 7, 1001-1005 (2013). doi: 10.1038/nphoton.2013.274 | 
| [6] | Chen, W. J. et al. Experimental realization of photonic topological insulator in a uniaxial metacrystal waveguide. Nat. Commun. 5, 5782 (2014). doi: 10.1038/ncomms6782 | 
| [7] | Wu, L. H. & Hu, X. Scheme for achieving a topological photonic crystal by using dielectric material. Phys. Rev. Lett. 114, 223901 (2015). doi: 10.1103/PhysRevLett.114.223901 | 
| [8] | Gao, F. et al. Probing topological protection using a designer surface plasmon structure. Nat. Commun. 7, 11619 (2016). doi: 10.1038/ncomms11619 | 
| [9] | Lu, L., Joannopoulos, J. D. & Soljačić, M. Topological photonics. Nat. Photon 8, 821-829 (2014). doi: 10.1038/nphoton.2014.248 | 
| [10] | Khanikaev, A. B. & Shvets, G. Two-dimensional topological photonics. Nat. Photonics 11, 763 (2017). doi: 10.1038/s41566-017-0048-5 | 
| [11] | Ozawa, T. et al. Topological photonics. Rev. Mod. Phys. 91, 015006 (2019). doi: 10.1103/RevModPhys.91.015006 | 
| [12] | Smirnova, D., Leykam, D., Chong, Y. & Kivshar, Y. Nonlinear topological photonics. Appl. Phys. Rev. 7, 021306 (2020). doi: 10.1063/1.5142397 | 
| [13] | Segev, M. & . Bandres, M. A. Topological photonics: Where do we go from here? Nanophotonics 20200441 (2020). | 
| [14] | Parto, M., Liu, Y. G., Bahari, B., Khajavikhan, M. & Christodoulides, D. N. Non-Hermitian and topological photonics: optics at an exceptional point. Nanophotonics 20200434 (2020). | 
| [15] | Harari, G. et al. Topological insulator laser: theory. Science 359, eaar4003 (2018). doi: 10.1126/science.aar4003 | 
| [16] | Bandres, M. A. et al. Topological insulator laser: experiments. Science 359, eaar4005 (2018). doi: 10.1126/science.aar4005 | 
| [17] | St-Jean, P. et al. Lasing in topological edge states of a one-dimensional lattice. Nat. Photon 11, 651-656 (2017). doi: 10.1038/s41566-017-0006-2 | 
| [18] | Bahari, B. et al. Nonreciprocal lasing in topological cavities of arbitrary geometries. Science 358, 636-640 (2017). doi: 10.1126/science.aao4551 | 
| [19] | Zhao, H. et al. Topological hybrid silicon microlasers. Nat. Commun. 9, 981 (2018). doi: 10.1038/s41467-018-03434-2 | 
| [20] | Parto, M. et al. Edge-mode lasing in 1D topological active arrays. Phys. Rev. Lett. 120, 113901 (2018). doi: 10.1103/PhysRevLett.120.113901 | 
| [21] | Zeng, Y. et al. Electrically pumped topological laser with valley edge modes. Nature 578, 246-250 (2020). doi: 10.1038/s41586-020-1981-x | 
| [22] | Shao, Z. K. et al. A high-performance topological bulk laser based on band-inversion-induced reflection. Nat. Nanotechnol. 15, 67-72 (2020). doi: 10.1038/s41565-019-0584-x | 
| [23] | Zhang, W. et al. Low-threshold topological nanolasers based on the second-order corner state. Light Sci. Appl. 9, 109 (2020). doi: 10.1038/s41377-020-00352-1 | 
| [24] | Gao, X. et al. Dirac-vortex topological cavities. Nat. Nanotechnol. (2020). | 
| [25] | Kim, M., Jacob, Z. & Rho, J. Recent advances in 2D, 3D and higher-order topological photonics. Light Sci. Appl. 9, 130 (2020). doi: 10.1038/s41377-020-0331-y | 
| [26] | Liu, S. et al. Octupole corner state in a three-dimensional topological circuit. Light Sci. Appl. 9, 145 (2020). doi: 10.1038/s41377-020-00381-w | 
| [27] | Cai, X. et al. Symmetry-enforced three-dimensional Dirac phononic crystals. Light Sci. Appl. 9, 38 (2020). doi: 10.1038/s41377-020-0273-4 | 
| [28] | Xie, B. et al. Dirac points and transition towards Weyl points in three-dimensional sonic crystals. Light Sci. Appl. 9, https://doi.org/10.1038/s41377-020-00416-2 (2020). | 
| [29] | Xiong, Z. et al. Hidden-symmetry-enforced nexus points of nodal lines in layer-stacked dielectric photonic crystals. Light Sci. Appl. 9, 176 (2020). doi: 10.1038/s41377-020-00382-9 | 
| [30] | Dutt, A. et al. Higher-order topological insulators in synthetic dimensions. Light Sci. Appl. 9, 131 (2020). doi: 10.1038/s41377-020-0334-8 | 
| [31] | Wang, K. et al. Multidimensional synthetic chiral-tube lattices via nonlinear frequency conversion. Light Sci. Appl. 9, 132 (2020). doi: 10.1038/s41377-020-0299-7 | 
| [32] | Cohen, M.-I. et al. Generalized laws of refraction and reflection at interfaces between different photonic artificial gauge fields. Light Sci. Appl. 9, https://doi.org/10.1038/s41377-020-00411-7 (2020). | 
| [33] | Jamadi, O. et al. Direct observation of photonic Landau levels and helical edge states in strained honeycomb lattices. Light Sci. Appl. 9, 144 (2020). doi: 10.1038/s41377-020-00377-6 | 
| [34] | Bellec, M. et al. Observation of supersymmetric pseudo-Landau levels in strained microwave graphene. Light Sci. Appl. 9, 146 (2020). doi: 10.1038/s41377-020-00351-2 | 
| [35] | Yang, Y. et al. Non-Abelian generalizations of the Hofstadter model: spin-orbit-coupled butterfly pairs. Light Sci. Appl. 9, 177 (2020). doi: 10.1038/s41377-020-00384-7 | 
| [36] | Yang, Z. et al. Photonic Floquet topological insulators in a fractal lattice. Light Sci. Appl. 9, 128 (2020). doi: 10.1038/s41377-020-00354-z | 
| [37] | Zhou, P. et al. Photonic amorphous topological insulator. Light Sci. Appl. 9, 133 (2020). doi: 10.1038/s41377-020-00368-7 | 
| [38] | Cerjan, A. et al. Thouless pumping in disordered photonic systems. Light Sci. Appl. 9, 178 (2020). doi: 10.1038/s41377-020-00408-2 | 
| [39] | Xia, S. et al. Nontrivial coupling of light into a defect: the interplay of nonlinearity and topology. Light Sci. Appl. 9, 147 (2020). doi: 10.1038/s41377-020-00371-y | 
| [40] | Smirnova, D. et al. Room-temperature lasing from nanophotonic topological cavities. Light Sci. Appl. 9, 127 (2020). doi: 10.1038/s41377-020-00350-3 | 
| [41] | Hao, L. & Lu, L. Dirac-vortex topological photonic crystal fibre. Light Sci. Appl. 9, https://doi.org/10.1038/s41377-020-00432-2 (2020). | 
| [42] | Wang, D. et al. Enhancing the graphene photocurrent using surface plasmons and a p-n junction. Light Sci. Appl. 9, 126 (2020). doi: 10.1038/s41377-020-00344-1 | 
| [43] | Pacheco-Peña, V. & Engheta, N. Temporal aiming. Light Sci. Appl. 9, 129 (2020). |