[1] [1] Krauss T F. Why do we need slow light[J]. Nat. Photon., 2008, 2(8): 448-450.

[2] [2] Pedaci F, Barland S, Caboche E, et al. All-optical delay line using semiconductor cavity solitons[J]. Appl. Phys. Lett., 2008, 92(1): 011101.

[4] [4] Khurgin B J. Optical buffers based on slow light in electromagnetically induced transparent media and coupled resonator structures: Comparative analysis[J]. J. Opt. Soc. Am. B, 2005, 22(5): 1062-1074.

[5] [5] Okawachi Y, Bigelow M S, Sharping J E, et al. Tunable all-optical delays via Brillouin slow light in an optical fiber[J]. Phys. Rev. Lett., 2005, 94(15): 153902.

[6] [6] Zhang T. A framework for fiber delay-line buffers in packet-based asynchronous multi-fiber optical networks (PAMFONET)[J]. Int. J. Commun. Syst., 2012, 25(2): 158-168.

[7] [7] Pisco M, Ricciardi A, Campopiano S, et al. Time delay measurements as promising technique for tilted fiber Bragg grating sensors interrogation[J]. IEEE Photonics Technology Letters, 2009, 21(23): 1752-1754.

[8] [8] Jung B M, Shin J D, Kim B G. Optical true time-delay for two-dimensional X-band phased array antennas[J]. IEEE Photonics Technology Letters, 2007, 19(12): 877-879.

[9] [9] Jung B M, Yao J P. A two-dimensional optical true time-delay beamformer consisting of a fiber Bragg grating prism and switch-based fiber-optic delay lines[J]. IEEE Photonics Technology Letters, 2009, 21(10): 627-629.

[10] [10] Sakamoto T, Matsui T, Tsujikawa K, et al. Hole-assisted dual concentric core fiber with ultralarge negative dispersion coefficient of-13,200 ps/nm/km[J]. Applied Optics, 2011, 50(18): 2979-2983.

[12] [12] Bajcsy M, Zibrov A S, Lukin M D. Stationary pulses of light in an atomic medium[J]. Nature, 2003, 426(6967): 638-640.

[13] [13] Baba T, Mori D. Slow light engineering in photonic crystal[J]. J. Phys. D. Appl. Phys., 2007, 40(9): 2659-2664.

[14] [14] O’Faolain L, Schulz S A, Beggs D M, et al. Loss engineered slow light waveguides[J]. Opt. Expr., 2010, 18(26): 27627-27638.

[15] [15] Petrov A, Krause M, Eich M. Backscattering and disorder limits in slow light photo-nic crystal waveguides[J]. Opt. Expr., 2009, 17(10): 8676-8684.

[16] [16] Minkov M, Savona V. Wide-band slow light in compact photonic crystal coupled-cavity waveguides[J]. Optica, 2015, 2(7): 631-634.

[17] [17] Kubo S, Mori D, Baba T. Low-group velocity and low-dispersion slow light in photonic crystal waveguides[J]. Opt. Lett., 2007, 32(20): 2981-2983.

[18] [18] Wang Z, Chong Y D, Joannopoulos J D, et al. Reflection-free one-way edge modes in a gyromagnetic photonic crystal[J]. Phys. Rev. Lett., 2008, 100(1): 13905.

[19] [19] Wang Z, Chong Y D, Joannopoulos J D, et al. Observation of unidirectional backscattering-immune topological electromagnetic states[J]. Nature, 2009, 461(7265): 772-775.

[20] [20] Tao K Y, Xiao J J, Yin X B. Nonreciprocal photonic crystal add-drop filter[J]. Appl. Phys. Lett., 2014, 105(21): 211105.

[21] [21] Huang C, Jiang C. Nonreciprocal photonic crystal delay waveguide[J]. J. Opt. Soc. Am. B, 2009, 26(10): 1954-1958.

[22] [22] Poo Y, Wu Ruixin, Lin Zhifang, et al. Experimental realization of self-guiding unidirectional electromagnetic edge states[J]. Phys. Rev. Lett., 2011, 106(9): 093903.

[23] [23] Fang Y T, He H Q, Hu J X. Transforming unidirectional edge waveguide into unidirectional air waveguide[J]. J. Sel. Top. Quantum Electron., 2016, 22(2): 4901109.

[24] [24] Sun Y X, Kong X K, Fang Y T. Competition and transformation of modes of unidirectional air waveguide[J]. Opt. Commun., 2016, 376: 115-117.