Supplemental material
We used an 808 nm diode laser to preirradiate S3 film and studied the effect of
the preirradiating on the dynamics of holographic grating growth. As shown in Fig. A,
the absorption of Ag nanoparticles (NPs) was sharply decreased at wavelength from
~650 nm to ~1000 nm, but increased from ~450 nm to ~650 nm, indicating the
increasing amount of small Ag NPs after photodissolving some large Ag NPs. The
overall absorption dropped after water rinsing, especially in the short wavelength
range, which might be due to the loss of some small NPs detaching from the
surrounding TiO2 medium in the irradiation and rinse process. The preirradiated and
rinsed film shows much faster holographic grating response compared with the
original one (Fig. B), in accordance with our anticipation. The lowered diffractive
efficiency was probably due to the loss of Ag volume by photodissolution and rinse.
Such response acceleration suggested that grating response can be tuned by suitable
preirradiation process.
Figure (A) Absorption spectra of the original Ag/TiO2 film (a) and those after 808nm
laser irradiation for 1h (b) plus water rinse (c). (B) Rise of the first-order diffractive
signal of the original sample (a) and that after laser irradiation and water rinse (b),
corresponding to absorption curves (a) and (c) in panel A, respectively.