An optical integrated circuit for time-division 2-D velocitymeasurement

An LiNbO₃ optical integrated circuit pigtailed with two single-mode fibres, which allows time-division two-dimensional velocity measurement, is discussed. To detect time-division multiplexed beat signals corresponding to velocity components v_X and v_γ of a moving object, a waveguide switch is integrated on a Z-propagating LiNbO₃ substrate of 28×7 mm² in addition to a waveguide interferometer with a frequency shifter. In the optical IC, either v_X or v_γ could be measured selectively with signal-to-noise ratio of 20 dB by driving an electronic gate placed after a photodiode in synchronization with the waveguide switch