Skip to main content

Ultra-Compact Terabit Plasmonic Modulator Array

Koch, Ueli, et al. “Ultra-compact terabit plasmonic modulator array.” Journal of Lightwave Technology 37.5 (2019): 1484-1491.


A new plasmonic transmitter solution offering 0.8 Tbit/s on an ultra-compact 90 μm × 5.5 μm footprint is introduced. It comprises a densely arranged four-channel plasmonic phase modulator array that directly interconnects an optical fiber array. Each plasmonic modulator features high-index grating couplers-for direct and efficient conversion from a fiber mode to a plasmonic slot mode and vice versa-and a plasmonic waveguide-for efficient high-speed modulation. The individual devices achieve data rates of 200 Gbit/s with a symbol rate of 100 GBd.
Electrical and optical crosstalk between neighboring modulators were found to have no significant influence on the data modulation experiment. The modulator array has been tested in a 100 GBd experiment with signals at a single wavelength (mimicking a space division multiplexing scheme) and at different wavelengths (mimicking a wavelength division multiplexing experiment).

Fig. 2.

Plasmonic phase modulator concept for a single device. (a) 3-dimensional rendering of the plasmonic phase modulator consisting of high-index silicon grating couplers (dark blue), a gold plasmonic slot waveguide (gold) and the cores of an optical fiber array (grey). The inset shows the facet of the fiber array. Neighboring cores with a 12 µm pitch were used to couple light into and out of the modulator. (b) Cross-section along the device showing the grating coupler geometry and schematic of the vertically incident fiber mode that is converted to a horizontally propagating plasmonic mode. (c) Cross-section across the plasmonic slot waveguide which is filled by a nonlinear organic electro-optic material (purple). In this configuration, light and electrical signal are both confined to the plasmonic slot leading to strong field enhancement, high field overlap and therefore strongest light-matter interaction.