I have written an article for JPSJ News & Comments. Have a look at “Nontrivial Topology of Nontopological Nonlinear Waves.”
See also old ones.

Nontrivial Topology of Nontopological Nonlinear Waves
Kyoka Sato, Takahiro Fukui
J. Phys. Soc. Jpn. 92,  073001 (2023).
So Small Implies So Large: For a Material Design
Toshikaze Kariyado
J. Phys. Soc. Jpn. 88,  083701 (2019).
Scattering of Dirac Fermions with Doubling
Atsushi Toyoda, Tsuneya Ando
J. Phys. Soc. Jpn. 79,  094708 (2010).