Open AccessSpatially resolved cross-sectional refractive index profile of fs laser–written waveguides using a genetic algorithm
Author(s) -
Antoine Drouin,
Pierre Lorre,
Jean-Sébastien Boisvert,
Sébastien Loranger,
Victor Lambin Iezzi,
Raman Kashyap
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.002488
Subject(s) - optics , laser , interferometry , refractive index , femtosecond , waveguide , materials science , mach–zehnder interferometer , refractive index profile , measure (data warehouse) , photonics , physics , computer science , database
Laser-written waveguides in glass have many potential applications as photonic devices. However, there is little knowledge of the actual profile of the usually asymmetric refractive index (RI) change across the femtosecond (fs) laser-written waveguides. We show, here, a new nondestructive method to measure any symmetric or asymmetric two-dimensional RI profile of fs laser-written waveguides in transparent materials. The method is also suitable for the measurement of the RI profile of any other type of waveguide. A Mach-Zehnder interferometer is used to obtain the phase shift of light propagating transversely through the RI-modified region. A genetic algorithm is then used to determine the matching cross-sectional RI profile based on the known waveguide shape and dimensions. A validation of the method with the comparison to a RNF measurement of the industry-standard SMF-28 is presented, as well as a demonstration of its versatility with measurements on fs laser-written waveguides.