Jinman Lv, Binbin Hong, Yang Tan, Feng Chen, Javier Rodríguez Vázquez de Aldana, Guo Ping Wang. Mid-infrared waveguiding in three-dimensional microstructured optical waveguides fabricated by femtosecond-laser writing and phosphoric acid etching[J]. Photonics Research, 2020, 8(3): 257