An opto-electronic integrated circuit includes an optical splitter (12, 13A, 13B) formed on a substrate, the optical splitter branching an input optical signal into N (N is an integer of 2 or more) optical signals, and outputting the optical signals, and N optical phase modulators (15A-15D) formed on the substrate for the respective optical signals output from the optical splitter, the optical phase modulators adjusting the phases of the optical signals based on a phase modulation characteristic in which the phase change amount changes depending on the wavelength of light, and output the optical signals.