Characterization of photopolymers used in laser 3D micro/nanolithography by means of laser-induced damage threshold (LIDT)

An ISO certified laser-induced damage threshold testing method was applied to characterize photopolymers widely used in 3D laser micro/nano-lithography. For the first time, commercial as well as custom made materials, including epoxy based photoresist (SU-8), hybrid organic-inorganic polymers (OrmoComp and SZ2080), thermopolymer (PDMS) and pure acrylate (PMMA), are investigated and directly compared. The presence of photoinitiator molecules within host matrix clearly indicating the relation between damage threshold and absorption of light is revealed. To simulate single- and multiphoton absorption processes optical resistance measurements were carried out at both fundamental (1064 and 1030 nm) and second harmonic (532 and 515 nm) wavelengths with laser pulse duration’s representing nanosecond and femtosecond regimes. Damage morphology differences from post mortal microscopic analysis were used to enrich the discussion about the possible breakdown mechanisms. The obtained characteristic values of damage threshold reveal potential of photopolymers and their possible applications in high power lasers.