In this study, we improved the hydrogen production efficiency by combining a photosystem I/platinum nanoparticle composite with an artificial light harvesting dye, Lumogen Red.

A stress sensor based on a dye-doped polymeric optical fiber is able to detect stress by simple comparison of two luminescence peaks from a pair of energy transfer organic dyes. Coumarin 540A (donor) and Rhodamine 6G (acceptor) were doped in the core and cladding of the fiber, respectively. For various laser wavelengths, the change in the near-field pattern and visible emission spectrum upon variation in the fiber bending diameter was evaluated. From a comparison with a low-numerical-aperture fiber, it is shown that the sensitivity of the sensor is controllable by optimization of the waveguide parameters.

In order to propose a multimode polarization-maintaining fiber in a large core diameter, polarization-maintaining graded-index plastic optical fiber (PMGIPOF) was fabricated using a birefringence-reduced copolymer of poly(methyl methacrylate/benzyl methacrylate). Successful reduction of orientational birefringence in the PMGIPOF was verified using polarized optical microscopy. The extinction ratio measured from the PMGIPOF was significantly higher than the value obtained for the step-index (SI) POF (14.3 and 0.5 dB for 1 m, respectively). Photoelastic birefringence in the PMGIPOF was studied using fiber macrobending. Retardation induced by the macrobending was observed in a manner of high regularity in the PMGIPOF, where as the other types of POFs did not show such regularity. Furthermore, the polarization-maintaining property of the PMGIPOF was effective at maximum 10 m propagation. † Part of the "Larry Dalton Festschrift".

Photosynthetic pigment–protein-based biophotovoltaic devices are attracting interest as environmentally friendly energy sources. Photosystem I (PSI), a photosynthetic pigment–protein, is a proven biophotovoltaic material because of its abundance and high charge separation quantum efficiency. However, the photocurrent of these biophotovoltaic devices is not high because of their low spectral response. We have integrated an artificial light-harvesting antenna into a PSI-based biophotovoltaic device to expand the spectral response. To fabricate the device, a perylene di-imide derivative (PTCDI) was introduced onto a TiO2 surface as an artificial antenna. In the photovoltaic cells formed by the PTCDI/PSI-assembled TiO2 electrode, the magnitude of the incident photon-to-current conversion efficiency spectrum was significantly enhanced in the range 450–750 nm, and the photocurrent increased to 0.47 mA/cm2. The result indicates that the photons absorbed by PTCDI transfer to PSI via Förster resonance energy transfer.