a semiconductor optical device and an optical device array is provided which can be used in an optical logic circuit , photonic switching oeic , etc . the device includes a light amplifying arrangement provided on a bypass waveguide that connects a plurality of optical waveguides , thereby enabling improvement of the light crosstalk and the light propagation loss . in particular , by virtue of providing a light amplifying means in addition to the light deflecting portion , noise components are not amplified , and , therefore , the sn ratio is markedly increased .