Tunable surface plasmon resonance enhanced fluorescence via the stretching of a gold quantum dot-coated aluminum-coated elastomeric grating substrate.

In this study, the surface plasmon resonance (SPR)-enhanced fluorescence properties of gold quantum dots (AuQDs) on an aluminum (Al)-coated polydimethylsiloxane (PDMS) grating substrate were investigated by changing the grating pitch via mechanical stretching. The SPR-excitation wavelength of the AuQDs/Al-coated PDMS-grating substrate was tuned by changing the incident light angle from 5° to 60° and stretching it from 0 to 1.0 mm. In addition, the SPR-enhanced fluorescence tuning ability was studied using an AuQD/Al-coated PDMS-grating film by stretching the substrate. The SPR-enhanced fluorescence (SPF) of the AuQDs on the Al-grating was observed using a violet laser as the excitation source at 405 nm with p-polarization. The wavelengths of the SPR excitation, corresponding to the SP-dispersion mode of +1, were shifted to a longer wavelength upon stretching the grating substrate from 0 to 1.0 mm. By stretching the AuQDs/Al-grating PDMS substrate, the SPR-enhanced fluorescence intensity increased at fixed incident angles of 15° and 35°, whereas the SPR-enhanced fluorescence intensity decreased at 40°. Moreover, the SPF could be tuned to exhibit different properties in tunable optical sensors.