https://doi.org/10.1051/epjconf/201921513001
Femtosecond Laser Micromachining of Fabry-Pérot Interferometers for Magnetic Field Sensing
1
CAP – Centre for Applied Photonics, INESC TEC, Rua do Campo Alegre 4150-179, Porto, Portugal
2
Department of Physics and Astronomy, Faculty of Sciences of University of Porto, Rua do Campo Alegre 4169-007, Porto, Portugal
* Corresponding author: joao.m.maia@inesctec.pt
Published online: 10 September 2019
Fs-laser micromachining is a high precision fabrication technique that can be used to write novel three-dimensional structures, depending on the nature of light-matter interaction. In fused silica, the material modification can lead to (i) an increase of the refractive index around the focal volume, resulting in the formation of optical circuits, or (ii) an enhancement of the etch rate of the laser-affected zones relative to the pristine material, leading to a selective and anisotropic etching reaction that enables fabrication of microfluidic systems. Here, both effects are combined to fabricate a Fabry-Pérot interferometer, where optical waveguides and microfluidic channels are integrated monolithically in a fused silica chip. By filling the channel with a magnetic fluid whose refractive index changes with an external magnetic field, the device can be used as a magnetic field sensor. A linear sensitivity of -0.12 nm/mT is obtained in the 5.0±0.5 to 33.0±0.5 mT range, with the field being applied parallel to the light propagation direction.
© The Authors, published by EDP Sciences, 2019
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
