Quasi-phase-matched second-harmonic generation indiazo-dye-substituted polymer channel waveguides

First-order quasi-phase-matched (QPM) second-harmonic generation (SHG) is demonstrated in a poled diazo-dye-substituted polymer channel waveguide. The channel waveguide with a nonlinear grating was fabricated by the serial grafting technique using conventional photolithography and reactive ion etching. The dependence of the conversion efficiency on both the waveguide parameter and the grating structure was derived theoretically. A normalized internal conversion efficiency of 1.1% W^-1 cm^-2 at 1.586 μm was obtained in the fabricated waveguide with a phase-matched interaction length of 3.4 mm. The experimentally obtained conversion efficiency is compared with the theoretical value, taking into account the effect of mode-mismatching and propagation loss     

Potential use of cyclodextrins to enhance the solubility of YM466 in aqueous solution

Various solubilizing agents for YM466, a new Factor Xa inhibitor, were investigated to begin designing the aqueous formulation for subcutaneous administration. The tentative target concentration was 5 mg/mL. First, three kinds of buffer solutions (glycine-HCl, citrate, and lactate) were examined for their solubilizing effects. The dissolution rate of YM466 in lactate buffer was the fastest, as determined by visual examination at room temperature. The dissolution rate of YM466 in lactate buffer was enhanced, without degradation, by heating at 40 degrees C, and YM466 solution at a concentration of 1 mg/mL became transparent 10 min after the start of heating. The solubility of YM466 increased along with lactate concentrations ranging from 50 mM to 200 mM and reached a high of 1.3 mg/mL after increasing lactate concentration to 200 mM at 5 degrees C. The addition of cyclodextrins beta-cyclodextrin (beta-CD), 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD), and gamma-cyclodextrin (gamma-CD), but not alpha-cyclodextrin (alpha-CD), had remarkable impact on its solubility, and 7-8 mg/mL of YM466 was dissolved by the addition of HP-beta-CD or gamma-CD. These results demonstrated that YM466 was included in cyclodextrins and that the inclusion formations required a cavity size larger than alpha-CD. Based on the calculation from the linear portion of the phase solubility diagrams, apparent stability constants of alpha-CD, beta-CD, HP-beta-CD, and gamma-CD at 5 degrees C were estimated to be 2M(-1), 206M(-1), 143M(-1), and 276M(-1), respectively. Therefore, we found that gamma-CD has the largest inclusion capacity.     

Fibre-optic polarising beam splitter employing birefringent-fibre coupler

An in-line fibre-optic polarising beam splitter, consisting of a fused birefringent-fibre coupler, is reported. Splitting of the orthogonally polarised lights was accomplished by increasing the difference of coupling ratios for the two polarisation modes. When a light at 1.402 ?m wavelength was coupled to the input lead, each polarisation was split on to different output leads, showing extinction ratios of more than 17 dB in both leads.