Recent developments in laser nanotechnologies allow overcoming optical limitations at the $100\mathrm{nm}$ level of spatial resolution. However, at such distances spatial restrictions on nanostructuring can be imposed by nonlocal response of the media. In the present paper, we consider nanostructuring by means of locally initiated radical polymerization of multifunctional monomers. Such local initiation can be provided, for instance, by femtosecond laser techniques. We theoretically analyze the limitations imposed by diffusion on the formation of two separate nanofeatures such as voxels, rods, and plates. Owing to the percolationlike transition occurring during the polymerization process, mathematical criteria for possible separation of such features are formulated. We develop a theoretical approach by consecutively taking into account diffusion of radicals of growing length. This approach allows us to estimate a characteristic spatial scale which determines the spatial resolution for the particular polymerizing system. For several realistic polymerizable resins, this resolution limit was estimated to be on the order of $10–100\mathrm{nm}$.

Colloidal particle lens array (CPLA) proved to be an efficient near-field focusing device for laser nanoprocessing of materials. Within CPLA, spherical particles do not act as independent microlenses. Due to the coupling of the spherical modes, the field near the clusters of spherical microparticles cannot be calculated by means of the superposition of Mie solutions for individual spheres. In the paper, the electromagnetic field distributions near laser-irradiated clusters of dielectric microspheres with configurations that match the fragments of the close-packed CPLA are studied. It is shown that some practically important mode coupling effects can be understood in terms of an effective immersion medium formed for the spherical particle by its surrounding.

We consider laser nanostructuring of the material surface by means of a colloidal particle lens array. Here, the monolayer of dielectric micro- or nanospheres placed on the surface acts as an array of near-field lenses that focus the laser radiation into the multitude of distinct spots, allowing the formation of many structures in a single stage. We show that conversion of a small part of the energy of the femtosecond beam into the second harmonic (SH) is an efficient way to increase the surface density of obtained nanostructures. By combining the fundamental frequency and the SH, one benefits both from the power of the former and from the focusing ability of the latter. This combination provides an efficient nanostructuring with sphere diameter close to the wavelength of the second harmonic. The possibility to create arrays of nanostructures with surface density above $5\times {10}^8\hspace{0.17em}{\text{cm}}^{-2}$ with femtosecond Ti:sapphire laser operating at 800 nm was demonstrated by employing 0.45 μm spheres.

Hexagonally shaped apertures on metal-coated colloidal lattices of microspheres have been observed within certain parameter regimes of femtosecond Ti:sapphire-laser irradiation. The occurrence of such structures is explained by electromagnetic field interferences caused by the array of microspheres. The calculations are based on the splitting of the incident laser field into narrow paraxial Gaussian beams and their subsequent tracing and summation.