Measurement of the refractive index profile of waveguides using defocusing microscopy - Lages, Eduardo; Cardoso, Wilder; Almeida, Gustavo Foresto Brito; Siman, Lívia; Mesquita, Oscar; Mendonça, Cleber Renato; Agero, Ubirajara; Sebastião Pádua (Applied Optics, 2018)