Ansys Lumerical Phased Array Lidar Simulations: Part 3

Hello, in this video we'll be talking about how numerical methods can be used to perform a system level analysis. We'll be continuing with the example of waveguide-based lidars. So, to recall, we basically have an array of waveguides, as shown here, which scatter light and form a beam.

By controlling the relative phases of light going into this waveguide, we can do beam steering, controlling the light into different directions. In the last couple of videos, we've seen how numerical modes can be used to study the mode inside the waveguide and study directional couplers.

We've also talked about how FDTD can be used to look at far fields of a single antenna, as well as an array of antennas.

We'll be talking about how FDTD can be used to look at far fields of a single antenna, as well as an array of antennas, and how beam steering can be performed, and how the beam will actually look like in the far field. Interconnect can be used to simulate the whole system.

For a lidar, this system will consist of a source, a modulator, a series of modulators, waveguides, and an antenna array.

All these elements have properties, such as insertion loss for waveguides, and different coefficients that determine how much the phase will change for a particular length of propagation when a certain amount of voltage is applied for the modulator.

All these can be integrated into a single platform, which is interconnect. Before we actually look at the lidar example, I just want to briefly show you the overall layout or how it actually looks like in interconnect, and what the building blocks are that we'll be using.

First, you have the library over here, which is called the element library. You can choose a bunch of sources, such as optical lasers, and choose the kind of laser you want. You can choose modulators, pulse generators, sequence generators, and waveguides, among others.

You can explore all this according to your application. Here, I'm just showing the components we'll be needing. First, you have the laser source. Then, you have a waveguide coupler. You send in light into one of the ports, and it's split into two components.

One of these components will go to a waveguide, and then from this waveguide, it will go to a phase transfer. The second beam will go through an optical modulator, and an electrical voltage can be applied to it. The output port will then have a modulated signal.

Another feature of interconnect is that you can actually put in a scripted element. A scripted element is an element that can be defined by a script, and you can create or define its ports.

The setup script defines your variables and parameters, the ready script defines when the element is activated, the go script does certain kind of processing, and the wrap up script produces an array with respect to time because we would be varying parameters with time.

Now, let's go to the actual layout for LiDAR. We have the source, a bunch of optical modulators, and the modulation signal is given somewhere below. We take this signal and split it up into different outputs, each of which is then sent to the modulator.

This is sent to different waveguide couplers, and then it's sent to the scripted array element, which in our case is the phased array. The phased array uses some of the data available after the FDTD simulations, which we did last time.

We can define our go scripts, which will determine the direction of the beam width based on the phase of the input signal. As we had seen in the first video, by giving appropriate uniform phase shift to all the different elements of an antenna, you can choose the direction of your beam steering.

At the output, we have the direction vectors, which are given by ux and uy, the x and y component of your position vector of your beam spot, and the beam widths, given by ux and uy. You can also look at the values of theta and phi directly.

We can do all sorts of interesting things using interconnect. For example, in the optical modulator properties, you can define your coefficients, which determine how the phase changes.

Plus, you can include things like insertion loss, absorption coefficients, and even inside a waveguide coupler, you can define your insertion loss.

Interconnect allows you to visualize your actual system setup, integrate results obtained from other modules, like numerical mode solutions and FDTD, and visualize the end results. I hope you like this video, and for details, you can always look at the numerical knowledge base.

Thanks a lot, and see you until next time.