A physical-optics based concept for geometric and diffractive light shaping
Strasbourg, 23 April 2018, SPIE Photonics Europe (paper WS200-4)
The manipulation, by suitable components, of the light generated by a source or an illuminated object is the essential task in the design of imaging and non-imaging optical systems. Typically, both the modeling and the design of such systems is performed with ray optics. However, recent developments in optical modeling facilitate a fast physical-optics model which also provides a deeper insight into optical design, thus enabling the formulation of powerful design techniques for light shaping by both diffractive and freeform components.
In physical optics light is represented by electromagnetic fields. A single field can exist, depending on its characteristics at different planes in space, in different zones, e.g. the far field zone. We therefore introduce the concept of geometric and diffractive zones of fields. Light shaping can be carried out by means of both smooth freeform surfaces and micro-structured surfaces (aka diffractive elements). Both types of light-shaping elements (smooth and micro-structured) may be applied in both types of zones (diffractive and geometric) of an electromagnetic field, depending on the desired effect. We describe and demonstrate design techniques for different applications of light shaping, including smooth and micro-structured surfaces, for different types of sources. The modeling is done vectorially in full and it therefore includes polarization and non-paraxial effects as well. The examples are demonstrated using the fast-physical optics software VirtualLab Fusion.
Non-Sequential Optical Modeling with VirtualLab Fusion
Tokyo, 25th of April, 2018, OPIE Exhibition Talk
VirtualLab Fusion—the known fast physical optics software—provides different approaches for non-sequential simulations through the entirety or part of an optical system. In non-sequential simulations with both ray and field tracing the user can control which light-propagation paths are to be considered. It is possible to switch between sequential and different degrees of non-sequential light (ray and field) tracing. At the same time, systems can be modeled conveniently and in a much more compact form. The investigation of etalons or ghost images generated by back-reflections is easily performed, so that countermeasures can be considered where necessary.
Non-sequential simulations require the accurate consideration of energy conservation. After all, it is of paramount importance to know how much energy the different deflected light portions carry. Otherwise no meaningful result can be expected. VirtualLab’s field tracing engine takes care of this by tracing the full electromagnetic field, considering polarization and coherence effects. VirtualLab provides different Maxell solvers, ranging from the approximated to the fully rigorous, which can be applied at will for different parts of the system: this results in an unparalleled versatility to adjust simulation time and accuracy to the specific needs of the user.
Considering the full capacity of VirtualLab by using also its grating and waveguide analysis tools, highly complex waveguide setups containing diverse grating structures can be modeled, analyzed and optimized. The evaluation of efficiencies of even subwavelength gratings is done rigorously. This way the analysis of grating components as parts of larger systems is made possible, a feat that would be impracticable if performed with universal Maxwell solvers for the whole system at once.
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