Low-loss multiple-slot waveguides fabricated by optical lithography and atomic layer deposition

We demonstrate silicon-based multiple-slot waveguides filled with dual atomic layer deposited oxide layers. Slot modes for both polarizations, transverse electric (TE) and transverse magnetic (TM), are supported in the waveguide. Propagation loss in the order of 8 dB/cm is achieved for the TE-polarization and 4 dB/cm for the TM-polarization in the waveguides with dual (Al 2 O 3 -TiO 2 ) thin film layers. The devices are fabricated using low-temperature complementary metal-oxide-semiconductor compatible processes. To our knowledge, this is the first demonstration of dual-filled slot waveguides