Quiz — Ansys Lumerical FDTD — Sources

Which of the following statements are true?

Which of the following plane wave types should be used to inject light at a non-normal angle over a broadband wavelength range?

Which of the following boundary conditions should be used to inject a planewave at a non-normal angle over a broadband wavelength range?

The following is a screenshot of a simulation about the scattering of light from a single nanoparticle on a substrate. Select all the images with a problem in the setup? 

Which option should be used to define the beam profile if the desired beam is a highly focused beam with a beam waist radius of 1 micron and wavelength 0.5 microns? 

The mode source CANNOT be used to 

What is the name of the result which can be obtained from the dipole source which gives the actual power emitted by the dipole source in the simulation? 

What field values are required in order to set up an import source?

Which of the following statements is true when using a TFSF source? 

Which type of source is recommended for simulating OLEDs? 

How can you ensure that the mode calculated by the mode source is accurate? 

Which property of a Gaussian source determines whether the beam converges or diverges as it propagates from the source injection plane? 

What boundary conditions should be used to simulate a periodic grating structure with a broadband planewave source at normal incidence? 

Which of the following properties of the import source can be set after importing the desired field profile data? 

To complete the "Sources" section of the course, answer the questions below.

Files required for the hands-on exercise:

Exercise 1 Script File

Instructions:

1. Use the provided script file "Exercise 1" which sets up a simulation region with a silicon waveguide tilted at 45 degrees. 

2. Insert an appropriate source into the simulation region that will allow you to find and inject a specific mode of the waveguide. Set the injection axis to “x-axis” and injection direction to “forward”.

3. Edit the source and modify the settings to find the fundamental TE mode of the waveguide at a wavelength of 1.55 um.

Exercise 1

Question: What is the effective index of the fundamental TE mode?

Insert your answer as a number with two decimal places precision

For example, if the answer is 0.2549, type in 0.26

The goal of this exercise is to obtain the scattering cross-section of a 50 nm gold nanoparticle for a wavelength of 0.55 um. This means that we want to measure only the light scattered by the particle.

The cross-section analysis group sets up a box of monitors and returns a result named “sigma” which is the cross-section as a function of wavelength. 

Instructions:

1. Download and run the Exercise 2 Script File which sets up a 50 nm diameter gold sphere, the simulation region, and a mesh override region. A cross-section analysis group is also added.

2. Add the appropriate source type to the simulation.

3. Modify the source dimensions so that it fully illuminates the particle with a single wavelength of 0.55 um while allowing only scattered light to reach the box of the cross-section analysis group.

4. Modify the span of the existing mesh override region to fit the source settings and run the simulation.

5. After running the simulation, right-click on the "cross_section" analysis group in the Objects Tree and select Visualize -> sigma from the context menu. In the visualizer window, you can see the value of the sigma result by hovering over the data point in the plot with the mouse cursor. You can also find the value of sigma by clicking on the “View Data” element in the Attributes table of the visualizer to show the “View Data” button. Clicking on the “View Data” button will open a new window with a table showing the value of the plotted sigma result.

Exercise 2

What is the value of scattering cross-section sigma at 0.55um?

Insert your answer as a number with two decimal places precision and scientific notation.

For example, if the answer is 3.1415e-12, type in 3.14e-12