10 research outputs found
Holography and Holographic Interferometry with a near IR Sentitive photopolymer System
Full text linkHolography and Holographic Interferometry with a near IR Sentitive photopolymer System
No full textHolographic images of test targets were reconstructed from a new, self-processing photopolymer material. A laser diode operating at 780Â nm was used in the experiments. Possible effects of the polarization of the construction beams on the reconstructed image were also studied. The applicability of this material to real time holographic interferometry was demonstrated.
Fabrication of microlenses and optical waveguides by self-guiding photopolymerization
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Photogenerating Silver Nanoparticles and Polymer Nanocomposites by Direct Activation in the Near Infrared
Get PDFThis work reports on an improvement of the photochemically assisted synthesis of silver nanoparticles by direct photoreduction of AgNO3 with a laser source emitting in the near infrared range (NIR). For this, polymethine dyes were used as the photoactive agents. Both the effects of central chain structure and activation intensity were investigated. The reduction kinetics was followed up by UV-Vis spectroscopy, and the particles size was evaluated by transmission electron microscopy. The results showed that light intensity affects both the average size and size distribution of Ag nanoparticles generated through this process. The particles can also be generated in situ in a photopolymerizable formulation so that metal/polymer nanocomposites become available through a one-step photoassisted process on the basis of NIR activation. The process described herein is very fast (seconds to a few minutes), and it readily lends itself to automatization for mass production of micro-optical elements implemented directly onto integrated NIR sources
Near-infrared photopolymerization: Initiation process assisted by self-quenching and triplet-triplet annihilation of excited cyanine dyes
No full textInternational audienceThe mechanism of radical polymerization photoinitiated by a near-infrared absorbing indotricarbocyanine (HITC) was investigated using an indirect kinetics method based on the photobleaching dynamics of the dye. Despite similar photophysical features in glycerol and in pentaerythritol triacrylate monomer, HITC undergoes a very fast photobleaching in the acrylate resin which leads to photopolymerization at high power regime. The addition of an amine induces the decrease of photopolymerization threshold by a factor 5 with unexpected dye regeneration. These effects were correlated to the reactivity of the reduced and oxidized forms of HITC produced via triplet–triplet annihilation and ground state quenching processes
A microtip self-written on a vertical-cavity surface-emitting laser by photopolymerization
No full textInternational audienceWe present the integration of a self-aligned microtip on a vertical-cavity surface-emitting laser Í‘VCSELÍ’ by near infrared photopolymerization. This one-step fabrication process is triggered by the laser source itself. It is based on the use of photopolymers sensitive at the lasing wavelength and can be applied to VCSEL devices after their process fabrication. We have characterized the fabricated microtips and shown that they focus laser light at few micrometers from the device. The applications of this simple method may concern VCSEL beam shaping as well as the fabrication of microprobes for near-field optical microscopy. VCSELs Í‘vertical cavity surface-emitting lasersÍ’ are now key light sources for photonic interconnects and for instrumentation and sensing applications. The potentialities which have already been demonstrated as well as the flexibility of these laser devices have recently strongly contributed to the rise of extended applications related to microsys-tems and in particular to biomedical instrumentation
