Fabrication of two-dimensional lattices by using photosensitive sol–gel and four-beam laser interference

This work demonstrates a promising method to fabricate 2D lattices by using photosensitive sol–gel method combining with four-beam of a 350.7 nm Kr ion laser interference. Photosensitive TiO2 gel films with chelate complexes as precursors are fabricated. The characteristics of UV and IR spectra of the films and their variations in the process of laser irradiation are investigated. The results show that the gel films had an absorption peak at about 358 nm due to the formation of chelate complex. This peak gradually decreases with irradiation in time, which indicates the photosensitive properties of the TiO2 films. A flexible four-beam interference system is proposed. Given incident angles 20.5° and 44.5°, the lattices with pitch of 700 nm and 326 nm are fabricated, respectively. The diffraction phenomenon of the 700 nm lattices is investigated by inverse method. The results are fully consistent with the 2D crystal diffraction theory.

Research Highlights
► An Improved sol-gel method --- photosensitive sol-gel is proposed, which endows the film with photosensitivity.
► Using photosensitive sol-gel, TiO2 photosensitive gel films are prepared. The gel films had an absorption peak at about 358nm, which will gradually decreases with UV irradiation due to the photodecomposition.
► Using TiO2 photosensitive gel films above, 2D lattices with different pitches can be prepared flexibly by multi-beam laser interference but not using optical resist. The diffraction of 2D lattices is consistent with the 2D crystal diffraction theory.