In this work, the effects of femtosecond laser irradiation and doping with plasmonic gold nanorods on the degree of conversion (DC) of a urethane dimethacrylate (UDMA)–triethylene glycol dimethacrylate (TEGDMA) nanocomposite were investigated. The UDMA-TEGDMA photopolymer was prepared in a 3:1 weight ratio and doped with dodecanethiol- (DDT) capped gold nanorods of 25 × 75 or 25 × 85 nm nominal diameter and length. It was found that the presence of the gold nanorods alone (without direct plasmonic excitation) can increase the DC of the photopolymer by 6–15%. This increase was found to be similar to what could be achieved with a control heat treatment of 30 min at 180 °C. It was also shown that femtosecond laser impulses (795 nm, 5 mJ pulse energy, 50 fs pulse length, 2.83 Jcm−2 fluence), applied after the photopolymerization under a standard dental curing lamp, can cause a 2–7% increase in the DC of undoped samples, even after thermal pre-treatment. The best DC values (12–15% increase) were obtained with combined nanorod doping and subsequent laser irradiation close to the plasmon resonance peak of the nanorods (760–800 nm), which proves that the excited plasmon field can directly facilitate double bond breakage (without thermoplasmonic effects due to the short pulse length) and increase the crosslink density independently from the initial photopolymerization process.
A status report is presented about the Nanoplasmonic Laser Induced Fusion Experiment (NAPLIFE). The goal is to investigate and verify plasmonically enhanced phenomena on the surfaces of nanoantennas embedded in a polymer target at laser intensities up to a few times W/cm and pulse durations of 40–120 fs. The first results on enhanced crater formation for Au-doped polymer targets are shown, and SERS signals typical for and bound vibrations are cited. Trials to detect ratio by means of LIBS measurments are reported. Plasmonics has the potential to work at these intensities, enhancing the energy and deuterium production, due to thus far unknown mechanisms.
Passive and active targets, both implanted with gold nanoprisms, were designed to achieve enhanced, uniform power absorption during two-sided illumination with short laser pulses. The capabilities of uniform, single-peaked Gaussian and adjusted nanoresonator number density distributions were compared. The average local E-field inside the gain medium and at the nanoprism surface was mapped as a function of the pump E-field strength and dye concentration, and the optimal parameters were selected based on the achievable local E-field. A comparative study was performed on passive and active targets to determine the most favorable distribution type and to consider the advantages of dye doping. The adjusted distribution is proposed for both passive and active targets. Dye doping is advantageous in all distributions as it results in decreasing the minimal standard deviation of the near-field enhancement (NFE), the delay of the minimal standard deviation in the power loss and deposited energy, and the standard deviation of the NFE, while increasing the FOM of the NFE in the uniform and adjusted distributions. Dye doping allows for decreasing the delay of the minimal standard deviation in the NFE, increasing the mean NFE, and decreasing the standard deviation of the power loss and deposited energy in the uniform, Gaussian, and adjusted distribution, respectively.