# How to build a model of thermal phase shifter?

#1

Hi,
I want to build an interconnect model of Thermal phase shifter? I could not find a related topic. Where should I start ?

#2

Hi,
This thermally tunable waveguide model is built based on MODE Solutions ans DEVICE simulation results.

Here is an example test file:thermally_tuned_waveguide.icp (470.6 KB)
Model Development

Parameter extraction
Please refer to the [Thermally Tuned Waveguide] (https://kb.lumerical.com/en/index.html?thermal_thermally_tuned_waveguide.html ) page for detailed information on the component level simulations using DEVICE and MODE Solutions. All the files mentioned below can be found in the LCML_resource folder in the download page.

1. Open the project file thermal_tuning_waveguide_2D.ldev in DEVICE and run with the default settings. The temperature distribution profile will be saved to T.mat .
2. Open the project file thermal_tuning_waveguide_2D.lms in MODE Solutions and disable the “temperature” object. Run a frequency sweep and export the mode data to thermal_tuning_waveguide.ldf" for INTERCONNECT.
3. Run the script file thermal_tuning_waveguide_sweep.lsf . This will extract the effective index changes vs. temperature (input power) and save the data in thermally_tuned_wg_neff_power.dat .

INTERCONNECT
The thermally tunable waveguide has an internal circuit that is very similar to that of the [PN phase shifter] (LCML - Phase shifter based on PN junction | lcml_ps_pn_1550), except that the Optical Modulator Measured element now uses the effective index perturbations as a function of the heating power ( thermally_tuned_wg_neff_power.dat ). The electrical input is voltage, and assuming the resistance is 50 ohm, the voltage is converted to power through an Electrical Multiplier and an Electrical Constant Multiplier (gain = 0.02).

## Test

Download the simulation file thermally_tuned_waveguide.icp` from the top of this page. In this simulation file, the thermally tuned waveguide is measured by an Optical Network Analyzer (ONA). Run the sweep object “sweep_voltage” defined in the file. The following plot is the phase shift in the waveguide under different heating power (represented by driving voltage) at 193.1 THz.

## Test

Hope this helps!

#3

Thank you very much!

#4

#6