Fully CMOS compatible subwavelength plasmonic slot waveguides for Si electronic-photonic integrated circuits

Subwavelength horizontal Al/SiO
2
/Si/SiO
2
/Al plasmonic slot waveguides with SiO
2
width at each side of ∼15 nm and Si width of ∼136, ∼87, and ∼43 nm are fabricated on SOI substrates using fully CMOS compatible processes. The propagation losses at 1550 nm TE are ∼1.01, ∼1.31, and ∼1.56 dB/µm, respectively, as measured by the standard cutback method. A simple taper coupler with length of ∼0.3–1 µm provides a high coupling efficiency of ∼66%–79% between the plasmonic slot waveguide and the standard Si dielectric waveguide. The plasmonic slot waveguide can achieve a direct 90o bend with a very low bending loss of ∼0.2–0.4 dB. The propagation, coupling, and bending losses depend weakly on wavelength in the c-band. The results demonstrate the potential for seamless integration of functional plasmonic devices in existing Si electronic-photonic integrated circuits.