Abstract
Agilent Technologies' approach to photonic cross-connect switching combines a silica-based planar lightwave circuit chip with a silicon-based actuator chip. The former contains two intersecting arrays of waveguides, with trenches etched into each crosspoint. The latter contains a matching pattern of electrically addressed resistive elements, and the two chips are hermetically sealed together. In the default state, the trenches, along with the rest of the sealed space between the two chips, are filled with a liquid whose index matches the waveguides. Optical signals passing along any guide simply pass on through. However, by activating a resistive element, a bubble can be created at that crosspoint, so that total internal reflection occurs at the side wall of the corresponding trench, and switching is achieved. Recent performance data of prototype 32x32 optical switches, including insertion loss, polarization dependent loss, switching time, and vibration sensitivity will be presented. Some of the intrinsic advantages of our technology will be discussed. One example is the built-in alignment of the waveguides and the trench walls at which switching occurs, which means that no optical realignments are necessary during operation. Another example is the potential for very low crosstalk, characteristic of the underlying phenomenon of total internal reflection.