Parallel-coupled Dual Racetrack Silicon Micro-resonators for Quadrature Amplitude Modulation

Left: Schematic of parallel-coupled dual racetrack resonators. Ein and Eout are the input and output fields of the central waveguide.

Right: Simulated intensity variations as the refractive index (Δn) of the waveguides in the top and bottom racetracks are modulated.

Invention Summary:

A parallel-coupled dual racetrack micro-resonator structure has been designed for phase-shift keying and M-ary quadrature amplitude modulation (QAM).

This structure comprises two racetrack resonators that are symmetrically side-coupled in parallel to a through waveguide in the center. The carriers can be injected or removed from the racetrack resonators using a pin diode or metal-oxide-semiconductor capacitor embedded in a silicon waveguide. The plasma dispersion effect of the injected carriers causes a change of refractive index in each resonator, modifying the cross-coupled resonances of the two racetrack resonators. The amplitude and phase of output optical signal can be controlled by the applied voltage to generate arbitrary M-ary quadrature signals.

Market Applications:

  • Optical communications
  • Phase-shift keying
  • Quadrature amplitude modulation


  • Higher spectral efficiency
  • Better tolerance to fiber non-linearity and chromatic dispersion
  • Low power consumption
  • Compact size, low cost
  • Suitable for arbitrary quadrature amplitude modulation
  • Resilient against fabrication imperfections

Intellectual Property & Development Status:

Issued Patent. Available for licensing and/or research collaboration.

Patent Information: