Effect of aggregation on the wavelength dependent optical limiting performance of silver nanoparticles in nanofibers and thin films
NANOSCALE ADVANCES, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1039/d6na00391e
- Dergi Adı: NANOSCALE ADVANCES
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, Directory of Open Access Journals
- Orta Doğu Teknik Üniversitesi Adresli: Evet
Özet
This study elucidates the role of nanoparticle agglomeration on wavelength dependence of nonlinear absorption and optical limiting by systematically investigating silver nanoparticle based (AgNP) polymer nanocomposites through aggregation-controlled thin films and nanofiber architectures. PMMA/AgNP nanocomposite thin films with dispersed and intentionally aggregated nanoparticle configurations were fabricated to directly examine the role of interparticle plasmonic coupling. Additionally, AgNP incorporated PMMA nanofibers with varying nanoparticle concentrations were employed to investigate nonlinear optical responses under geometrically constrained conditions. Ultraviolet-visible spectroscopy revealed pronounced spectral broadening and red-shifting of localized surface plasmon resonance bands in aggregated thin films, indicating strong interparticle coupling. On the other hand, nanofiber systems exhibited increased absorption behavior, which may be partly associated with increased scattering-related contributions arising from the polymer matrix. Open-aperture Z-scan measurements performed under nanosecond (532 and 1064 nm) and femtosecond (800 nm) excitation demonstrated strong nonlinear absorption in all nanocomposite thin films, governed by plasmon-enhanced excited state absorption processes. Furthermore, nanoparticle aggregation markedly enhanced nonlinear absorption by inducing local electromagnetic field amplification within closely coupled clusters, with possible additional contributions from scattering effects. As a result, the optical limiting performance was significantly improved, and the aggregated nanocomposite thin films exhibited an exceptionally low onset optical limiting threshold of 3.54 & times; 10-4 J cm-2 at 1064 nm. In nanofiber systems, increasing the AgNP concentration led to a higher number of scattering centers, which may contribute to enhanced nonlinear absorption and strengthen the overall nonlinear optical response. Compared to nanocomposite thin film systems, nanofiber architectures suppressed nanoparticle agglomeration, which consequently led to a relatively reduced nonlinear absorption response. These findings reveal that aggregated nanocomposite thin films outperform nanofiber systems via plasmonic coupling-driven field enhancement, highlighting structural design as a key parameter for optimizing nonlinear optical performance.