Good evening, build a demultiplexer based on 2D photonic crystal in Comsol and I would like to know how do I insert a Gaussine source at the input of device and ports to analyze the transmission at the outputs?
To configure a Gaussian source and ports for transmission analysis in COMSOL, you can follow these steps:
1. Configuring the Gaussian Source
You will first need to set up a Gaussian source, which can be achieved by setting up the input electric field with a Gaussian profile.
a. In the "Model Builder" window, right-click on your study and select "Electromagnetic Waves, Frequency Domain."
b. Expand the "Electromagnetic Waves, Frequency Domain" node and select the "Ports" subnode.
c. Click the "Add Port" button to create a new port. Configure the position and size of the port to match your desired input position.
d. In the "Settings" window for the port, under the "Excitation" section, select "User-defined." This will allow you to define the excitation function for the port.
e. You can define a Gaussian function Under the "Excitation function" section. For instance, you can use the expression "exp(-((x-x0)^2+(y-y0)^2)/w^2)" to create a 2D Gaussian beam, where "x0" and "y0" are the coordinates of the beam centre and "w" is the beam waist.
2. Configuring the Output Ports for Transmission Analysis
You can configure output ports for transmission analysis in a similar manner.
a. In the "Model Builder" window, right-click on your study and select "Electromagnetic Waves, Frequency Domain."
b. Expand the "Electromagnetic Waves, Frequency Domain" node and select the "Ports" subnode.
c. Click the "Add Port" button to create a new port. Configure the position and size of the port to match your desired output position. Repeat this step to add additional output ports as needed.
d. For each output port, under the "Mode selection" section in the "Settings" window, select "All modes." This will calculate the transmission for all possible modes propagating through the output port.
3. Performing the Transmission Analysis
a. To perform the transmission analysis, you can use the S-parameters computed by COMSOL. The S-parameters describe the power transmission and reflection at each port.
b. Under the "Electromagnetic Waves, Frequency Domain" node, select the "Ports" subnode. Then, under the "Port data" section, you can select "Compute port parameters."
c. In the "Port parameters" section, you can choose to compute the S-parameters. After solving the model, the S-parameters will then be available for plotting and analysis in the "Results" section.
Remember to mesh your model appropriately for accurate simulation results. Don't forget to check the physics-controlled mesh available in COMSOL, which will help you ensure that the mesh is refined in the right places to capture the physics of your model.
Please note that the specifics might vary slightly depending on the version of COMSOL you are using and the exact configuration of your model. Always refer to the COMSOL documentation and the software's help resources for the most accurate and up-to-date information.
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