Flexible Thermo-Optical Space Switch in SiON Planar Waveguides

A thermo-optically tunable planar waveguide space switch is presented that can be used either as a single 1-to-8 switch or as multiple parallel 1-to-4, 1-to-3 or 1-to-2 switches. This versatility results from the chosen switch layout, which resembles an arrayed waveguide grating wavelength multiplexer. Individual addressing of heaters on the array waveguides enable switching of input signals to output waveguide channels. The switch has been implemented in a
high-refractive-index SiON/SiO2 waveguide technology, which enables the realization of compact devices due to the small bending radii. We achieved isolations of the "off" channels to the "on" channel of up to 29 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 required functional configuration and are between 2.4 dB and 5.7 dB.