Polymer waveguide notch filter using two stacked thermooptic long-period gratings

A polymer waveguide notch filter using two stacked thermooptic long-period gratings is proposed. It is a long-period waveguide grating whose transmission spectrum can be dynamically controlled. Thermooptic index perturbation, i.e., grating is temporarily induced by two groups of periodic heaters stacked vertically on the filter surface. The periods of the two groups are determined such that two different resonance bands are generated in the spectrum by the respective groups. Thus, the overall spectrum may be actively shaped by controlling the individual power applied to the two groups. Its feasibility is demonstrated experimentally by fabricating it with thermocurable polymers.