Applications

Laser-induced photopolymerization, also known as direct laser lithography or direct laser writing, is a technique for the formation of three-dimensional (3D) micro- and nanostructures with variable architectures and subwavelength resolution.

The technique relies on a multiphoton absorption process in a material, such as photosensitive resin, typically transparent at the wavelength of laser radiation. The chemical change occurs at the laser focal spot via the absorption of two or more photons. The laser radiation is well-controlled for rapid prototyping of arbitrary 3D shapes with fine features. In particular, laser-induced photopolymerization is applied in the manufacturing of mesoscale optical, photonic, microfluidic components, as well as complex scaffolds for tissue engineering.

Laser-induced photopolymerization is associated mainly with petroleum-derived resins, but using bio-based materials obtained from renewable sources is becoming a trend. Such an environment-friendly approach offers easy processing, fulfills technological, functional, and durability requirements, and ensures increased bio-compatibility, recycling, and eventually lower cost. The research groups from Vilnius University and Kaunas University of Technology have recently employed a bio-based resin derived from soybean oil, which can be processed even without the addition of a photoinitiator. Their results show a high potential of the bio-based resins for high fidelity prototyping and additive manufacturing; see the publication for more details. 

The photopolymerization is effectively obtained using PHAROS and CARBIDE series femtosecond lasers with their fundamental wavelength (1030 nm) or higher harmonics (515 nm, 343 nm), or wavelength-tunable industrial-grade I-OPA (320 – 10000 nm). High short- and long-term stability together with high beam quality ensure the robust and precise formation of the 3D micro- and nanostructures.