Zemax OpticStudio does not include FDTD engine, however, reference shows an example of integrating Lumerical FDTD and Zemax OpticStudio for this process. This method is mainly used by flat metalens designer. To address the disadvantage of the previous process, where the system performance cannot be simulated before fabrication, Physical Optics Propagation (POP) together with FDTD can be used to accurately calculate the PSF. Similarly, although rays from “non-working” order can be traced, there is no diffraction efficiency computed, therefore no way to know the power ratio in stray light paths.įigure 1 A possible workflow to design DOE/metalens in OpticStudio.ġ.2 Phase profile -> microstructure -> verify with POP+FDTD For example, there is no way to check the real point spread function (PSF) considering all diffraction orders.
The disadvantage of this method is that designers may not be able to check the performance of the whole system.
Alternatively, reference shows how to design metalens for a given phase profile using Lumerical FDTD software. The macro to generate the blaze grating can be found in our Knowledgebase article How to calculate the sag of a diffractive optical element with a macro. It also discusses the fabrication with single-point diamond turning machine. Reference shows an example of generating blaze grating from given phase profile. The required design and fabrication methods can be very different depending on the types of microstructures. This chart does not cover the details of the design, for example, the microstructure can be traditional blaze grating or modern metalens. Figure 1 shows a flow chart for the process. Then the microstructure is designed based on the given phase profile. In this process, users first design the required phase profile for DOE/metalens with ray-tracing method. The main goal is to provide designers, new to this topic, a starting point to see what methods are available in OpticStudio.ġ.1 Phase profile -> microstructure -> experimental verification
In this blog post we start with a brief introduction of some possible design routes, with the full Knowledge Base Article provides details on the concept of phase profile and propagation methods in free space and DOE/metalens along with some useful DLLs customized for special phase profile design are introduced.
If users provide new information or have any requests, please feel free to reach out to us and we can update this article accordingly. Since the simulation technology develops fast, it is possible this article does not cover all the methods available. Many design processes require two different optical theory/algorithms to separately handle the beam propagation in free space and in microstructure, while others use only pure raytracing to achieve the goal. Designers need to decide the strategy for their systems case by case. There is no generalized method to handle all situations. But simulating and designing for systems that include DOEs or metalenses are always tricky.
Diffractive Optical Elements (DOEs) and Metasurfaces / Metalenses are gaining increasing popularity in optical system design, for applications ranging from cell phone lenses to AR/VR headsets, from 3D sensing to illumination.