Two-section reversed /spl Delta//spl beta/ switch with uniform electrodes and domain reversal

The performance of the reversed-/spl Delta//spl beta/ LiNbO/sub 3/ optical directional coupler (DC) switch with electrodes of opposite polarity is known to be more tolerant to variations in coupling length than that of the single-section DC. However, sectioned electrodes are incompatible to a single microwave source and, therefore, preclude the use of the device in high-speed applications. In this letter, we discuss the operation and results of a modified DC that uses a domain reversal and uniform electrodes that can be readily matched to a microwave source. A crosstalk of -34 dB was measured in an experimental device, fabricated in Z-cut LiNbO/sub 3/. Factors which improve device performance are also discussed.