Physical optics education is already an indispensable part in optics education, because of the fact that more and more optical devices are designed, and naturally, are working based on physical-optics principles. Various physical optics effects and phenomena, although being covered in certain textbooks, they still turn out to be difficult to fully understand, due to the disconnection between the purely theoretical blackboard derivation and the completely practical laboratory observation. One way to overcome that, in our opinion, is to employ VirtualLab Fusion – physical optics software – as a bridge connecting both sides. Light is represented as vectorial electromagnetic fields in VirtualLab Fusion and it provides an easy access to the visualization and analysis, leading to a convenient understanding of the nature of light, without loss of any preciseness. With its help, we will demonstrate several physical optics effects as well as their applications in modern optics industry.
Optical fibers are widely used for collecting and monitoring light signals in modern optical metrology systems. The use of fibers helps reduce the size of optical system and makes the interconnection between systems convenient. But on the other side, the design and analysis of systems containing fibers often go beyond traditional ray-optics modeling. Because the interaction between light and fibers, with core diameter only several micrometers, requires electromagnetic field solvers. In this work, we present a physical-optics-based modeling technique for the complete optical system, including large-scale lenses and micro-scaled optical fibers. We investigate the coupling of electromagnetic fields into fibers using different lens systems, and especially, we perform tolerance analysis of given system with respect to shift and tilt of the fiber, as well as other components in the system.
Interferometer-based optical setups play an important role in modern optical metrology for different applications. Such setups often consist of multi-disciplinary components. This reveals new ways of improving the performance or enriching the functionality of the system, while at the same time leading to complexities and difficulties in system modeling and analysis. To overcome this, we present a physical-optics-based simulation approach. It is founded on a fully electromagnetic representation of light, and therefore includes the coherence and polarization effects which are of growing interest for modern interferometers. As examples, several typical optical interferometer setups are built up and analyzed. With the physical-optics modeling technique, we demonstrate and understand the functionalities of such setups, so as to help in the design of advanced optical interferometers.
The propagation of electromagnetic fields through inhomogeneous media is an essential requirement in the modeling and design of optoelectronic devices. In the most general case, this requires the application of finite-difference techniques in frequency or time domain, or other rigorous solutions of Maxwell’s equations, which often results in too high a numerical effort for practical applications. However, if the inhomogeneity is represented by a smoothly varying refractive index, e.g. in a GRIN lens, fiber, or acousto-optic modulator, the propagation of the electromagnetic fields can be modeled by fast algorithms. They are based on recent major achievements in fast physical optics and make use of the identification of the diffractive and geometric zones of electromagnetic fields. Dependent on the situation, this can enable vectorial propagation through graded-index media in seconds, including even the crosstalk between polarization directions. The theory and the resulting algorithms include established beam propagation techniques as special cases, e.g. the popular paraxial split-step technique.
Shaping of LED white light is of increasing interest for several industrial applications. There are several known design concepts available. However these concepts suffer from high uniformity errors, low efficiencies, chromatic aberrations and/or high tolerance sensitivity. To overcome these limitations we present a novel design concept which is based on the design of aperiodic scattering cell arrays. In a first design step, a unit scattering cell is designed. Afterwards this cell is periodically replicated. Finally the periodicity of the array is broken using parametric optimization. Obtained design results are compared with experimental data.
Wollaston prisms and the modified Wollaston prisms, which are interesting for various applications like optical metrology, topography of surfaces and biological imaging, has been theoretically studied and also been practically applied. The previous studies are mostly based on ray tracing analysis and, as a result, the information that can be obtained are somehow restricted. In this paper, we propose a geometric field tracing technique for the simulation of light propagation through Wollaston prisms. In geometric field tracing we seek for the solutions to Maxwell's equations under the geometrical optics approximation, so that all the properties of light as electromagnetic field are retained. Using the proposed simulation technique, we present the simulation of a differential interference contrast (DIC) microscopy, in which the modified Wollaston prism is used as the key component.
Ray tracing and split-step method are the most efficient techniques to model multi-mode fiber. In this work, we also propose a geometrical optics based approach, which is beyond ray tracing. This approach, which is mathematically based on Runge-Kutta methods, handles not only ray information but light field information, e.g. amplitude and polarization. Then we discuss and compare the different techniques by the example of coupling of a VCSEL source into a multi-mode fiber.
In this work the authors investigate the potential of a smooth field decomposition method to improve simulation efficiency in modelling scattering situations. Two examples of particular simulation set-ups are presented and analysed.
Ray optics has constituted the fundament of optical modeling and design for more than 2000 years. In recent decades, the introduction of ray tracing software has brought a powerful optical design technology to everybody dealing with optics and photonics. However, with the development and availability of advanced light sources, the capability to produce micro and nano structures, the need for high NA systems, and a boost in the variety of applications and related demands on optical functions, the limitations of ray optics become obvious more often. Optical modeling based on physical optics is required and is the logical next step in the development of optical design. This requires a generalization of ray tracing and its connection with diffractive modeling techniques.
The thin element approximation is an efficient algorithm to analyze diffractive optical elements (DOEs), whose feature size is large enough compared with the working wavelength. However, the thin element approximation is only valid under the condition of normal illumination. We hereby extend an algorithm, which is called the parabasal thin element approximation, to include the non-perpendicular illumination. More specifically, the thin element approximation is valid for paraxial incident beam, while the parabasal thin element approximation is valid for parabasal beam∗. In this article, we present the algorithm of the parabasal thin element approximation and compare the result with that of rigorous method. All the simulations are based on field tracing1 and done with the optical software VirtualLabTM.2
The thin element approximation is an efficient algorithm to analyze diffractive optical elements (DOEs), whose
feature size is large enough compared with the working wavelength. However, the thin element approximation
is only valid under the condition of normal illumination. We hereby extend an algorithm, which is called the
parabasal thin element approximation, to include the non-perpendicular illumination. More specifically, the thin
element approximation is valid for paraxial incident beam, while the parabasal thin element approximation is
valid for parabasal beam. In this article, we present the algorithm of the parabasal thin element approximation
and compare the result with that of rigorous method. All the simulations are based on field tracing and done
with the optical software VirtualLab™.
This article introduces an efficient tilt operator for harmonic fields. In optical modeling and design, a field tilting
operation is often needed, e.g., the propagation of a harmonic field between non-parallel planes, since most of
the existing propagation operators only deal with the case of propagation between parallel planes. Such operator
enables the modeling of various optical components, like the case of prisms and tolerancing with tilted components.
The tilt operator is a rigorous method to calculate vectorial harmonic fields on tilted planes. The theory
applies a non-equidistant sampling in the k-space of the field before rotation in order to obtain an equidistant
sampling of the rotated field. Different interpolation techniques are employed for the non-equidistant sampling
in the k-space of the initial field and their performances are evaluated.
Besides the tilt operator, the propagation method of harmonic fields through planar interface is proposed as well.
The application of both methods makes it possible to model a sequence of tilted optical interfaces, e.g., prisms.
At the end of this article, a dispersive prisms example is presented. All simulations are done with the optics
software VirtualLabTM.1
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