Computer Science
Electro-optic modulator with periodic p-n junction in slow-light waveguide grating

Electro-optic modulator with periodic p-n junction in slow-light waveguide grating


The invention concerns an electro-optical modulator, wherein a band-edge slow light in silicon waveguide gratings is applied to Mach-Zehnder modulators based on the plasma dispersion effect, reaching improved modulation efficiency and reduced energy dissipation.

The present invention allows production of slow-light modulators for silicon photonics with reduced energy dissipation.


The invention is based on an interleaved p-n junction with the same periodicity as the silicon waveguide grating is used, in order to achieve optimal matching between the electromagnetic field profile and the depletion regions of the p-n junction. The resulting modulation efficiency is strongly improved as compared to common modulators based on normal rib waveguides, even in a bandwidth of 20-30 nm near the band edge, while the total insertion loss due to free carriers is not increased.


  • Strongly improved modulation efficiency in a bandwidth up to 20–30 nm
  • Increased slow-light modulator bandwidth
  • Reduced loss of the slow-light structure relative to a lateral p-n junction
  • Improved efficiency and reduced free-carrier induced insertion losses


  • Telecommunication networks
  • Electro-optical conversion of information in datacenters


Lucio Andreani, Dario Gerace, Marco Passoni, John William Whelan-Curtin



Electro-optical modulators; Slow light; Interleaved p-n junction; Plasma dispersion effect




Università di Pavia 75% University of Cork 25%

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