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In this work, gold films on two different types of substrates were fabricated by electron beam (e-beam) evaporation, and the femtosecond laser-induced damage properties were evaluated. The first sample was gold film deposited on fused silica, whereas the second was gold deposited on photoresist. 1-on-1 damage tests were implemented by an 800 ± 30 nm laser with pulse duration of 30 fs. Different damage thresholds and morphologies were obtained for the two samples. The damage threshold of the gold film on fused silica was 0.64 J/cm 2 , with the typical damage morphology of thermal ablation and melting; the damage threshold of the gold film on photoresist was 0.30 J/cm 2 , with the typical damage morphology of blisters or peeling off. In order to better understand the impact of the substrate on the properties of the whole sample, the normalized electric field intensity, temperature, and thermal stress distributions were calculated. The adhesion between the gold film and substrate were measured and the experimental results well agreed with the theoretical analysis. The results indicate that gold films deposited onto grating-structured fused silica will have more powerful laser damage resistance performance. [ABSTRACT FROM AUTHOR]

Au-coated gratings (ACGs) for chirped pulse compression were irradiated using 800 ± 35 nm multiple laser pulses with duration of 30 fs. The laser-induced damage threshold (LIDT) of Au-coated gratings decreases from 0.35 J/cm 2 to 0.10 J/cm 2 with the increased pulse shots. The near threshold damage feature of Au-coated gratings at different pulses shows blisters. It is indicated that the gradually increased blister height with increasing multiple pulses on ACGs is caused by the accumulation effect. The damage morphologies combine with simulated results indicate that the damage of the ACGs can be attributed to the pinholes at the base of grating pillars and the separation of gold coating and photoresist gratings caused by the photoresist absorbed the incident laser energy. Therefore, we consider the damage threshold can be enhanced by optimizing coating deposition technology to reduce pinholes density and increase the adhesion between the gold and the photoresist. [ABSTRACT FROM AUTHOR]

An investigation of the impact of solvent content on polymerization feature size in multi-photon polymerization is presented. The negative tone, epoxy photoresist SU-8 is employed, and variety pre-baking time is set to obtain different solvent content. A convenient method, exposure under long-focal length and single pulse, is suggested to evaluate the impact of solvent. By measuring the polymer size under microscope, it shows that the polymerized diameters are reduced by ~40% due to only 4% loss of the solvent content. The inhibition of the mobility of photon-induced H+ cations due to the less solvent is considered to be responsible for the refinement of polymer feature size. It is because that the mobility of photon-induced H+ cation from high to low concentration area is restricted by reducing the solvent. The adjusting solvent content shows its potential to refine the feature size of MPP without influencing the degree of polymerization. • Vaporizing the solvent content could refine the feature size of MPP in SU-8 2075 photoresist. • A long focal-length and single pulse exposure was proposed to realize the exposure of multi-photon polymerization. • Feature sizes of the polymerization were evaluated by the microscope at the micro-scale. • Polymer diameters were reduced by ~40% via reducing the solvent content by ~4%. [ABSTRACT FROM AUTHOR]