Multilayer metal–dielectric planar waveguides for subwavelength guiding of long-range hybrid plasmon polaritons at 1550 nm

Abstract

The characteristics of long-range hybrid plasmonic modes guided by multilayer metal–dielectric planar waveguides are investigated at the telecom wavelength. These multilayer structures are formed by sandwiching thin metallic stripes into horizontal silicon slot-like waveguides. Comprehensive numerical studies regarding the geometric parameters’ effects on the modal properties reveal that, by properly choosing the dimensions of the metal stripe and the low-index gaps between the stripe and the silicon layers, the symmetric hybrid modes supported by the structures could feature simultaneously ultra-long propagation distance (several centimeters) and subwavelength mode size. Consideration of possible fabrication imperfections shows that the optical performances of the waveguides are quite robust and highly tolerant to these errors. The presented multilayer plasmonic structures greatly extend the capabilities of conventional long-range surface plasmon polariton waveguides by successfully confining light into a subwavelength scale while maintaining the key advantage of enabling ultra-low-loss propagation, which could facilitate potential applications in ultra-long-range plasmon waveguiding and realizations of compact, high-performance photonic components, as well as building optically integrated circuits with complex functionalities.