An achromatic component shares a common focus at two wavelengths and is a commonly used device in optical assemblies. This work explores the cost versus performance tradeoff for several types of achromatic lenses: conventional doublets with homogenous glass elements, hybrid doublets with a diffractive surface, axial GRadient INdex (GRIN) lenses (where the index of refraction changes along the length of the lens), and radial GRIN lenses (where the index of refraction changes depending on radial position). First order achromatic principles will be reviewed and applied to each system as a starting point and refined through the use of ray trace software. Optical performance will be assessed in terms of focusing efficiency and imaging. Cost will then be evaluated by accounting for current manufacturing costs and retail price through several distributors.
Recent research has focused on developing low-bandgap polymers for harvesting solar energy, fine-tuning desirable properties including power conversion efficiency, carrier mobilities and broad light absorption. However, little attention has been paid to their nonlinear optical properties. We characterized the optical second harmonic generation of corona poled films of poly(cyclopenta[2,1-b;3,4-b']dithiophen-4-ylidenedioctylmalonate). Despite being amorphous and lacking a typical donor-acceptor dye, these films display large nonlinear optical susceptibilities. Coupled with their stability and low absorption in the relevant wavelength region, these polymer films compare favorably to other materials. Our results show the promise of low-bandgap polymers for nonlinear optical applications.
In light of the population aging in many developed countries, there is a great economical interest in improving the speed and cost-efficiency of healthcare. Clinical diagnosis tools are key to these improvements, with biophotonics providing a means to achieve them. Standard optical microscopy of in vitro biological samples has been an important diagnosis tool since the invention of the microscope, with well known resolution limits. Nonlinear optical imaging improves on the resolution limits of linear microscopy, while providing higher contrast images and a greater penetration depth due to the red-shifted incident light compared to standard optical microscopy. It also provides information on molecular orientation and chirality. Adaptive optics can improve the quality of nonlinear optical images. We analyzed the effect of sensorless adaptive optics on the quality of the nonlinear optical images of biological samples. We demonstrate that care needs to be taken when using a large field of view. Our findings provide information on how to improve the quality of nonlinear optical imaging, and can be generalized to other in vitro biological samples. The image quality improvements achieved by adaptive optics should help speed up clinical diagnostics in vitro, while increasing their accuracy and helping decrease detection limits. The same principles apply to in vivo biological samples, and in the future it may be possible to extend these findings to other nonlinear optical effects used in biological imaging.
Three-dimensionally (3D) ordered macroporous materials combine interesting structural and optical properties. Accessible and economic fabrication is essential to fully explore the unique possibilities these materials present. A common method to fabricate 3D ordered macroporous materials is by self-assembling colloids, resulting in so-called opals. A templating strategy is then often used to introduce additional functionality inside the porous structure, giving rise to inverse opals. In this work, we developed an easy and versatile method to fabricate highly uniform polymer inverse opals without overlayers. Briefly, our approach consists of sandwiching a resin melt between two opal templates, forcing all material inside or between the macroporous structures. The opal voids are fully filled and the superfluous melt material is extruded before curing the resin. Finally, the opal templates are removed by chemical etching. The resulting structures are freestanding 3D macroporous films with large-area uniformity, displaying strong photonic properties due to their structural order. Additionally, many applications require specific optical functionalities. The versatility of our templating method is uniquely suited for this purpose as it allows doping of the melt before infiltration. Therefore, we can incorporate a large variety of optical functions in the inverse opals using a single approach We believe this method will help the systematic investigation and improvement of existing effects in these structures, while providing a platform for the discovery and demonstration of novel effects. As this method combines 3D ordered macroporous materials with linear and nonlinear optical materials, it is even possible to tune optical interactions, which could be technologically relevant for OLEDs, solar cells, lasers, electro-optical modulators and optical switches.
Modifying and detecting the polarization of light is increasingly important in many contexts such as Faraday isolators and electro-optical modulators. In order to control the polarization of light, it is necessary to know the polarization characteristics of the materials used in the applications. To be able to (magneto-)optically characterize novel materials, we designed a setup using a single photoelastic modulator (PEM) to simultaneously detect natural and magnetic circular dichroism and circular birefringence over a large spectral range. We then theoretically analyzed and experimentally characterized the effect of non-idealities in the PEM on the setup and the resulting data. Our results demonstrate an influence of PEM non-idealities on the measured signals, resulting in non-negligible mixing of circular birefringence and circular dichroism signals. Our measurements of the wavelength dependence of these non-idealities reveal larger non-idealities towards shorter wavelengths. These results illustrate the necessity to take PEM non-idealities into account when working with PEMs, especially at shorter wavelengths or when dealing with signals spanning different orders of magnitude. PEM non-idealities, while frequently neglected in experimental setup design and theoretical derivations, are expected to be more complicated and possibly exert a larger influence on obtained results for experimental setups with multiple PEMs.
Second harmonic generation microscopy has recently become an important tool for studying materials. In this article, we use a recently developed analytical method, for second-harmonic generation microscopy, to determine the point group symmetry of micro crystals of enantiomerically pure 1,1’-bi-2-naphtol.
Magneto-optically active organic compounds are of great technological interest. In contrast to inorganic materials, used
in most current applications, organic materials have the advantages of fast response times, easy processing, low cost and
abundant resources of starting materials available. Conjugated organic molecules or polymers have been reported to be
eligible candidates for exhibiting magneto-optical responses. As part of an ongoing search in our group for efficient
magneto-optical materials, eight organic conjugated dyes were screened for their Faraday rotation responses. Based on
the obtained preliminary results, it is expected that planar, efficiently pi- conjugated molecules have a higher chance for
exhibiting significant magneto-optical responses. Further research will be undertaken to confirm this hypothesis.
In this work we present measurements of the switching of the Faraday effect in metal-organic compounds.
Faraday rotation is the rotation of the plane of polarization of linearly polarized light under the influence of a
magnetic field in the direction of propagation of the light. It is the magnetic equivalent of circular birefringence
and is related to magnetic circular dichroism via the Kramers-Kronig transformation. The Faraday effect is used
in optical isolators and magnetic sensors.
Faraday rotation and magnetic circular dichroism spectra have been calculated and measured for various
nanoparticles, nanocomposites, magnetic fluids and metal-organic complexes. These measurements and calculations
indicate that it is possible to change the magneto-optical response by changing the state of the molecule,
such as a change in protonation or oxidation state. The molecular environment also influences the magneto-optical
spectra of metal-organic complexes and organic molecules. Thus it is possible to change the Faraday
rotation spectrum by modifying the molecular environment or the molecule itself. We have measured the reversible
switching of the magneto-optical response by these principles. This easily induced reversible switching
opens the possibility of new devices such as switchable optical isolators.
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