Optical Fiber Interferometers Based on Arc-Induced Long Period Gratings at INESC TEC

Paulo Caldas; Gaspar Rego

doi:10.3390/s21217400

Optical Fiber Interferometers Based on Arc-Induced Long Period Gratings at INESC TEC

Sensors (Basel). 2021 Nov 7;21(21):7400. doi: 10.3390/s21217400.

Authors

Paulo Caldas^{1

2}, Gaspar Rego^{1

2}

Affiliations

¹ proMetheus, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial Nun'Álvares, 4900-347 Viana do Castelo, Portugal.
² Center for Applied Photonics, INESC TEC, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.

Abstract

In this work, we review the most important achievements of an INESC TEC long-period-grating-based fiber optic Michelson and Mach-Zehnder configuration modal interferometer with coherence addressing and heterodyne interrogation as a sensing structure for measuring environmental refractive index and temperature. The theory for Long Period Grating (LPG) interferometers and coherence addressing and heterodyne interrogation is presented. To increase the sensitivity to external refractive index and temperature, several LPG interferometers parameters are studied, including order of cladding mode, a reduction of the fiber diameter, different type of fiber, cavity length and the antisymmetric nature of cladding modes.

Keywords: long period grating; low-coherence interferometric; optical fiber interferometric sensors; true pseudo-heterodyne technique.

Publication types

Review