Fabrication of serially-grafted optical wave guide of organic functional crystal and polymer

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Organic crystal optical waveguides are promising device for practical photonic applications though because of their large optical loss, they should be serially grafted with transparent polymer waveguides. Among a variety of organic crystals we investigated an organic salt, 4-N, N-dimethylamino-4'-N-methyl-stilbazorium tosylate, DAST, an a promising functional crystal. It is of particular interest because its largest NLO coefficient d_<11> is 〜540V and electro-optic (EO) coefficient r_<11> is 〜55pm/V (λ=1.54μm). DAST crystal is relatively hard to fabricate optical waveguide because it is very easy to dissolve into organic solvents as well as in water. This is very critical because the selection of the waveguide fabrication methods will be limited.So we had used special lift off method to fabricate a serially grafted optical waveguide of DAST and transparent polymer. Based on the photolithography and reactive ion etching technology, we had succeeded to fabricate a serially grafted struct … More ure of the waveguide, for the first time as far as the combined waveguide of crystal and polymer. As far as NLO organic crystal waveguide concerns, only two molecular crystals that are usually insoluble in water were reported, though their loss was large, larger than 20dB/cm. In the case of the DAST, loss was around 10dB/cm and 〜6dB/cm with serially grafted structure of 5 mm long DAST. DAST serially grafted waveguide was also fabricated using photobleaching. We had already reported that the DAST crystal is photo-bleachable based on photo-isomerization and photodecomposition. So as a polymer waveguide, we had selected azobenzene-dye containing transparent polymer to photobleach. After synthesizing novel polyarylether with azo-dye, we have fabricated a serially grafted waveguide of DAST and the polyarylether. We had succeeded to fabricate it using this simple photobleaching technology.In conclusion, a serially grafted organic functional crystal and transparent polymer was successfully fabricated for the time as far as we know. The waveguide of the DAST crystal and polymer is expected to apply for functional optical circ in optical telecommunication system. Less