No abstract

Volume holographic phase gratings possessing the saturated refractive index modulation amplitudes as large as 4.5×10−2 were recorded at a wavelength of 532 nm in a photopolymerizable nanoparticle-polymer composite (NPC) film dispersed with ultrahigh refractive index hyperbranched-polymer (HBP) organic nanoparticles. This prominent result was achieved by a combination of the HBP nanoparticles with triazine and aromatic ring units and an electron donor/acceptor photo-initiator system doped in an acrylate monomer blend with low viscosity. As a result, efficient mutual diffusion of HBP nanoparticles and monomer having their very large refractive index difference took place. Obtained results suggest a potentiality of our newly developed HBP-dispersed NPC gratings as efficient volume holographic optical elements for various photonic applications including wearable headsets for augmented and mixed reality.

We demonstrate volume holographic recording  at a wavelength of 640 nm in a photopolymerizable nanoparticle-polymer composite (NPC) film dispersed with ultrahigh refractive index hyperbranched-polymer (HBP) organic nanoparticles. We employ a new photosensitizer-initiator system consisting of cyanine dye, triazine compound and borate salt for efficient radical generation in the red. We investigate the electron transfer and radical generation processes of the system by measuring fluorescence quenching and photopolymerization dynamics to find the optimum composition of the system for volume holographic recording. We show that recorded volume gratings of 0.5-µm spacing possess the saturated peak-to-mean refractive index modulation amplitudes as large as 3×10−2 at a readout wavelength of 640 nm. Our results show the usefulness of photopolymerizable HBP-dispersed NPCs for volume holographic recording materials for various photonic applications including security and color holograms, and volume Bragg grating devices in head-mounted displays.

Linearly-polarized, 12-W Yb-doped double-clad fiber laser has been constructed by use of polarization-maintaining fibers and an in-line polarizer. 2.2-W green light was also obtained by second harmonic generation in a periodically-poled MgO:LiNbO 3 .

The depletion of natural resources is a critical environmental issue, and the recovery, including reuse and recycling, of end-of-life assembled products is the key to reducing the use of natural resources. However, in order to reuse or recycle an assembled product, it is essential to consider the life expectancy or material type and the weight of the parts in the product. In addition, because the assembled products comprise various parts, manual disassembly is required, which entails high costs. To recover assembled products in an environmentally friendly and economical manner, part selection for disassembly is required. A part selection method is proposed with three selection types: reuse, recycling, and disposal. First, data-set preparation is addressed. Second, the method for selecting the disassembly parts using integer programming and the ϵ constraint method is explained. Finally, numerical experiments are conducted using the proposed part selection method with a computer as a case study. Lifetime changes of the parts/product are then analyzed.