was 0 1 db or less further the optical propagation loss of the waveguide was unchanged for more than 1 month under the condition of 75 u00b0 c 90 rh a single mode channel waveguide core diameter 8 u03bcm u00d7 8 u03bcm u03b4n 0 3 was produced using the same procedure as in example 12 except that a photosensitive substance h prepared from 100 weight of liquid acrylic oligomer represented by the following structural formula 19 and 2 weight of diphenyltriketonebenzoin as a photopolymerization initiator was used in place of the photosensitive substance d the resulting optical waveguide was cut to a length of 5 cm by a dicing saw and measured for optical propagation loss which was 0 5 db or less at wavelength 1 3 u03bcm and 5 0 db or less at wavelength 1 55 u03bcm polarization dependence of the optical propagation loss was 0 1 db or less at wavelength both 1 33 u03bcm and 1 55 u03bcm further the optical propagation loss of the waveguide was unchanged for more than 1 month under the condition of 75 u00b0 c 90 rh 240 g of phenyltriethoxysilane 20 g of methyltriethoxysilane 10 g of water 100 g of isopropylalcohol and 0 1 g of hydrochloric acid were mixed heated under reflux for 4 hours then solvents and the like were removed under vacuum using a rotary evaporator to give 112 g of colorless transparent oligomer c 50 g of the oligomer c 1 g of 3 glycidoxypropyltriethoxysilane 7 g of water 20 g of isopropylalcohol 2 g of ion exchange resin amberlite ira900 from aldrich co were charged into a reaction vessel heated at 80 u00b0 c for 12 hours while agitating the ion exchange.