Compact 1-to-8, double 1-to-4 or fourfold 1-to-2 space switch based on beam steering by a waveguide array

We present the implementation of an optical space switching concept based on thermo-optic beam steering in an arrayed waveguide grating (AWG). Individual addressing of heaters on the array waveguides enables flexible switching of input signals to output waveguide channels. The switch can be used either as a 1-to-8 switch or as multiple parallel 1-to-4, 1-to-3 or 1-to-2 switches. For the implementation we used our high-refractive-index SiON/SiO2 planar waveguide technology, which allows the realization of compact devices using small bending radii. We achieved isolations of the "off"-channels with respect to the "on"-channel of up to 27 dB for a 1-to-3 switch or better than 22 dB for all "off"-waveguides for a 1-to-8 switch. Total on-chip losses depend on the functional configuration required and are between 2.4 and 5.7 dB.