Thermo- and Electro-Optic Simulations

Thermo- and Electro-Optic Simulations

Temperature and external electric fields can have a significant influence on the propagation constants of modes in waveguides. Temperature changes can cause materials to expand or contract, while electric fields distort the internal shapes of crystalline materials. The Thermo- and Electro-Optic Simulation Module simulates, given all relevant material parameters, the temperature or electric field distribution induced by heaters or electrodes. You can design waveguide cross-sections, add (metallic) heaters or electrodes, and evaluate how the metals affect the loss and propagation constants. Then, either the induced temperature or electric field is calculated in the cross-section, which in turn induces local refractive index changes; perturbation techniques then calculate how the propagation constants of the optical waveguide modes change.


Fabrication technologies are not yet at a level where the exact phase relations between waveguides of different (or even nominally identical) lengths match the expected values to a sufficient degree. In most applications that rely on the phase of the light, devices will need to be tuned to the correct working point. Thermal tuning is the more common way to do this. The Thermo- and Electro-Optic Simulation Module quickly estimates power consumption required for a given phase shift, and optimizes the waveguide cross-section (including the heaters) for trade-offs between metal-induced loss and power efficiency.

Electro-optic effects tend to be much faster than thermo-optic effects, but they rely on specific crystalline materials. The Thermo- and Electro-Optic Simulation Module is suitable for the vast majority of cases in which the modes of the waveguides are very nearly linearly polarized.


Design of thermo-optic and electro-optic modulatorsDesign of thermo-optic and electro-optic modulators.


  • Each material can be given its own thermal and electrical properties
  • Static thermal and electrical fields are calculated using Finite Element Method
  • Perturbation techniques calculate the effect of the fields on the propagation constants of waveguide modes
  • Optical and thermal / electrical calculation windows can have vastly different sizes (typically, thermal simulations need to take the entire thickness of the wafer into account)
  • Allows for trade-off analysis between optical losses and efficiency of the thermal or electrical effects

Figure 1. Plot of the switching power versus the ridge width of a waveguide with a heater.