Colloidal Silver Nanoparticle Plasmonic Arrays for Versatile Lasing Architectures via Template-Assisted Self-Assembly

The characteristic narrow spectral features of surface lattice resonances emerge as great candidates for the rational design of optical nanocavities targeting enhanced light-matter interaction, ultrasensitive detection, or efficient light-energy conversion. Traditional fabrication of metal arrays involves thermal evaporation and annealing steps, limiting scalability and adaptability. In contrast, template-assisted self-assembly provides a high-throughput all-around approach for implementing colloidal plasmonic metasurfaces on a variety of different materials. Here, the use of pre-synthesized silver nanoparticles is designed and tested for the construction of versatile lasing architectures. Plasmonic arrays are prepared directly on top of the gain media (a photoresist thin film doped with Rhodamine B), creating optical nanocavities with quality factors as high as 85. The proposed architecture circumvents the need for an index-matching superstrate to promote the generation of collective resonances, leaving the plasmonic surface accessible for post-assembly modification. Additionally, the angular dispersion of the metasurfaces is used to modify the angle of the lasing emission, achieving both normal and off-normal lasing upon modification of the lattice parameter of the array. The results demonstrate how state-of-the-art colloidal self-assembly techniques offer a scalable and versatile alternative for the fabrication of plasmonic and photonic devices targeting advanced and non-linear optical phenomena.