Optical switching and power control in LiNbO₃ coupled waveguide arrays

A diversity of switching and power-distribution functions in coupled multi-waveguide arrays is discussed and demonstrated. Functionality is achieved by varying the effective index in each waveguide independently by means of the electro-optic effect. The splitting and switching functions are attained by the use of a multi-variable optimization procedure. Specificall,y we demonstrate [1 × 2] and [1 × 5] routing and power division and [2 × 2] cross-connection. Polarization diversity and polarization-independent switching are attained using a special crystal orientation and electrode configuration. Single-polarization routing was measured in most cases, with crosstalk figures of the order of - 15 dB. Polarization-independent switching was achieved with crosstalk of less than - 19 dB for a three-waveguide [1 × 2] switch. By addition of dummy guides, a polarization-independent [2 × 2] cross-connection function could be attained with crosstalk figures better than -30 dB.