# Find the Temperature Around a Heater

Editor: Heat project › Model, Setup and Results tabs · Python: td.HeatChargeSimulation

You get the temperature in the cross-section of a silicon waveguide under a heater, and how much the waveguide warms up.

# Before You Start

  • A new Heat project. See Create Your First Project and choose the HEAT tab.
  • The editor uses µm: thermal conductivity in W/(µm·K) and heat rates in W/µm³. For example, 1.4 W/(m·K) is 1.4e-6 W/(µm·K).

Cloud only

This run costs about 0.03 FlexCredits.

# Steps

  1. Click Domain on the canvas toolbar. Choose 2D, keep the design plane XY, and set Size to 10 and 6 (µm).

  2. In Model › Mediums, click +, then New Medium. Set Name to oxide and Thermal conductivity to 1.4e-6, and click OK. Add a second medium, silicon, with 1.5e-4.

    Medium form with the name oxide and the Thermal Properties: SolidSpec, Thermal conductivity 1.4e-6 W/(µm*K)

    Edit Medium form

  3. In Model › Structures, click +, then Rectangle. Add three rectangles, in this order:

    Name Center (µm) Size (µm) Medium
    cladding 0, 0 inf, inf oxide
    waveguide 0, 0 0.5, 0.22 silicon
    heater 0, 1.5 2, 0.2 silicon

    Where structures overlap, the one added later wins. So the cladding comes first.

  4. In Setup › Boundary Conditions, click +, then TemperatureBC. Keep Temperature 298.15 K, Placement SimulationBoundary and all Surfaces, and click OK. All edges of the domain then stay at 298.15 K.

  5. In Setup › Sources, click +, then Heat Source. Set Rate to 3e-4 W/µm³ and Structures to heater, and click OK.

    Edit HeatSource form with Rate 0.0003 W/µm^3 and the structure heater

    Edit HeatSource form

  6. In Setup › Configuration › Grid Specification, set Type to UniformUnstructuredGrid and Dl to 0.05 µm, and click OK. A new Heat project has no grid.

  7. Click Check Simulation and wait for Validation Passed. Click Run Simulation. When the Congratulations! dialog shows, click Go To Simulation Results.

# Check the Result

In the Results tab, open Monitor Datasets › domain_temp_monitor › Temperature. A new Heat project has this monitor; it covers the whole domain.

Results tab with the temperature map: the heater is hottest, at about 319 K, and the waveguide below it is at about 309 K

Results tab

The heater reaches about 319 K, 21 K above the edges. The waveguide, 1.5 µm below it, reaches about 309 K: it warms up by about 10 K. Hold the pointer over the map to read the temperature at a point.

In this setup, the temperature rise is proportional to the Rate. For about 5 K at the waveguide, halve the rate.

If the check shows an error, see Heat Troubleshooting.

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