Multi wavelength measuring of the gold nanoparticles by the optical fiber interferometer

Agrež, Vid (author), Kramar, Julij (author), Petkovšek, Rok (author)

An optical fiber-based Mach–Zehnder interferometer was developed for photothermal detection of gold nanoparticles in aqueous suspensions. The excitation laser locally heats the suspension, inducing a refractive index change that is detected as a phase shift in the interferometer's measuring arm. By employing excitation wavelengths of 450 nm and 525 nm, the wavelength-dependent absorption was analyzed and compared to Mie theory predictions, enabling simultaneous determination of particle size and concentration. The absorption cross-section ratio, calculated from measurements at both wavelengths, depends only on particle size and provides the basis for size determination without prior knowledge of concentration. The system demonstrated high sensitivity, with detection limits as low as 8 × 10⁶ particles per milliliter for 100 nm gold nanoparticles. The optical fiber-based architecture offers simplicity, robustness, and potential for integration into portable sensing systems for nanoparticle characterization and biosensing applications.

• Language: English
• Keywords: optical fiber interferometer, photothermal detection, gold nanoparticles
• Work type: Bibliography
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 7 str.
• Numbering: Vol. 408, art. 118046
• PID: 20.500.12556/RUL-182960
• UDC: 620.3
• ISSN on article: 1873-3069
• DOI: 10.1016/j.sna.2026.118046
• COBISS.SI-ID: 279851267
• Publication date in RUL: 29.05.2026

Record is a part of a journal

• Title: Sensors and actuators : Physical
• Publisher: Elsevier
• ISSN: 1873-3069
• COBISS.SI-ID: 23273477

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: vlakenski interferometer, fototermalna detekcija, zlati nanodelci

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P2-0270
• Name: Proizvodni sistemi, laserske tehnologije in spajanje materialov

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: L2-4485
• Name: Merjenje absorpcije črnega ogljika s sistemom na osnovi optičnih vlaken