Low-loss hybrid plasmonic waveguide with double low-index nano-slots

A hybrid plasmonic waveguide with double low-index nano-slots is introduced. The fabrication is simple and compatible with the standard processes for SOI wafers. The theoretical investigation shows that the present hybrid plasmonic waveguide has a low loss and consequently a relatively long propagation distance (at the order of several tens of lambda). For TE polarization, there is a strong field enhancement in the double nano-slots. More power is confined in the low-index nano-slots for a smaller core width. For a 50 nm-wide hybrid plasmonic waveguide with double 10 nm-wide slots, the power confinement factor in the nano-slots is as high as 85% and the effective area is as small as 0.007 microm(2) at 1550 nm. Consequently, the power density in the nano-slots becomes very high, e.g., >120 microm(-2), which is very desired for many applications. For the present hybrid plasmonic waveguide, the lateral dimension could be less than 50 nm and the calculated decoupled separation for two parallel identical waveguides is only 0.62 microm, which is helpful to realize photonic integration circuits with ultra-high integration density.