Magnetic Field Fiber Specklegram Sensors Based on Tb³⁺-Doped Magneto-Optical Glasses With High Verdet Constants

Author(s)

Cabral, Thiago D. ; Franco, Douglas F. ; Fujiwara, Eric ; Nalin, Marcelo ; Cordeiro, Cristiano M. B.

• Document type: Journal article
• Source: IEEE SENSORS JOURNAL; v. 23, n. 7, p. 8-pg., 2023-04-01.

Abstract

Optical fiber specklegram sensors (FSSs) for magnetic field measurements are reported. The probes are compact, with only a fiber length of similar to 100 mm exposed to a magnetic field and comprised of no-core fibers doped with terbium oxide (Tb4O7), so the Verdet constant is dramatically improved in comparison to regular commercial fibers (similar to 20x increase, 10-mol% fiber), greatly enhancing the modulation of the output specklegram. The response to static magnetic fields was evaluated for different concentrations (6-10 mol%) of Tb4O7, yielding an increase in sensitivity of up to 59x (8.78 x 10(-2) mT(-1), 10 mol%) and 6x resolution (1.86 x 10(-2) mT, 6 mol%) in relation to a regular silica multimode fiber (MMF). A simple setup with a He-Ne laser and inexpensive webcam charge-coupled device (CCD) camera was employed, producing results comparable to fiber sensors based on more complicated setups such as fiber interferometers. To the best of our knowledge, this comprises the first demonstration of highly multimode magnetic field FSS based on magneto-optical (MO) glass to capitalize on both the Faraday rotation and the polarization mode conversion. (AU)

• FAPESP's process: 14/50632-6 - Surface-plasmon resonance sensors based on microstructured optical fiber
• Grantee: Cristiano Monteiro de Barros Cordeiro
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 17/25666-2 - Development of an optical fiber force myography sensor for applications in human-robot interfaces
• Grantee: Eric Fujiwara
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/16900-9 - Preparation of heavy metal oxide glasses fibers with optical and magneto-optical properties
• Grantee: Douglas Faza Franco
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/19272-4 - Production of heavy metal optical fibers to be used in Faraday rotators
• Grantee: Douglas Faza Franco
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor