[1] [J], 560, 214-218(2018).
[2] [J], 140, 107074(2021).
[3] [J], 452, 233-237(2019).
[4] [J], 31, 091005(2019).
[5] [J], 17, 8310-8318(2009).
[6] [J], 10, S104-S111(2019).
[7] [J], 10, 9907-9921(2019).
[8] [J], 148, 105-109(2008).
[9] [J], 12, 218-224(2019).
[10] [J], 5, 20736-20753(2017).
[11] [J], 29, 30-37(2018).
[12] Stewart W J. Technique f measuring the refractive index profiles of graded optical fibers[C]Proceedings of Conf 100e. Tokyo, Japan, 1977: 395.
[13] [J], 18, 3265-3271(1979).
[14] [J], 7, 109-113(1975).
[15] [J], 14, 814-815(1975).
[16] [J], 50, 0406004(2021).
[17] [J], 13, 1475-1489(1995).
[18] [J], 82, 2730-2734(1997).
[19] [J], 18, 9-13(1979).
[20] [J], 36, 159-161(2007).
