Abstract

An optical phased-array structure can be created by depositing an array of interdigital finger electrodes having a linear variation in apodization on the top of an electrooptically-active planar waveguide (Fig. 1).⁽¹⁾ As a result of the linear electrooptic effect and the apodized-electrode array structure, a differential optical phase delay is induced between the adjacent light beams (defined by the adjacent electrodes) when a voltage is applied across the two terminal electrodes. Since the apodization varies linearly across the aperture of the light beam, a linear phase slope is induced across the aperture of the light beam at the output port. Thus, by varying the applied voltage one can vary this induced phase slope to deflect/switch and modulate the light beam in the plane of the waveguide. A model calculation for such an electrooptic phased-array (EOPA) structure in a Y-cut LiNbO₃ waveguide has predicted⁽¹⁾ a small drive voltage per resolvable beam position. For example, with a preliminary device using He-Ne laser light and an array with L = 1 cm and d/2 = 5μ the drive voltage per resolvable beam position was measured to be 6 volts.⁽¹⁾

© 1978 Optical Society of America