Routing and photodetection in subwavelength plasmonic slot waveguides

The ability to manipulate light at deeply sub-wavelength scales opens a broad range of research possibilities and practical applications. In this paper, we go beyond recent demonstrations of active photonic devices coupled to planar plasmonic waveguides and demonstrate a photodetector linked to a two conductor metallic slot waveguide that supports a mode with a minute cross-sectional area of ∼λ2/100. We demonstrate propagation lengths of ∼10λ (at 850 nm), routing around 90° bends and integrated detection with a metal-semiconductor-metal (MSM) photodetector. We show polarization selective excitation of the slot mode and measure its propagation characteristics by studying the Fabry-Perot oscillations in the photocurrent spectra from the waveguide-coupled detector. Our results demonstrate the practicality of transferring one of the most successful microwave and RF waveguide technologies to the optical domain, opening up many opportunities in areas such as biosensing, information storage and communication.