Method of encapsulating silver nanodots using porous glass and its application in Q-switched all solid-state laser

Here, we report on a packaging method for silver nanodots (SNDs) by using high-silicate porous glass. Millions of nanopores, which are randomly distributed in porous glass, are used as cells for SND nucleation and growth during the initial chemical-reduction process. Then, the sample is annealed at a high-temperature in a reducing atmosphere to impel the further SND growth and nanopore collapse. The compact SND-embedded transparent glass is synthesized in the end. Morphology characterization shows that the SNDs that are encapsulated in the sample have a uniform size of 1.5 to 4.5 nm. Both the sample's saturable and reverse saturable absorptions are observed under the irradiation of 100 fs laser pulses at 800 nm. Saturable absorption's threshhold is characterized to be 1.4 × 10¹¹ W/cm², which is much lower than what was ever reported. Furthermore, the SNDs-embedded silica as a saturable absorber (SA) has been demonstrated in the Q-switched Nd:YVO₄ laser. The pulse duration as short as 53 nanoseconds is obtained. To our knowledge, it is the first time that SNDs are used as a SA in the passively Q-switched all solid-state laser.