Our broad and diverse research interests are by no means limited to what is found here. Rather, this page serves as an example of some of the recent and current topics. If you are interested in learning more, please contact Prof. Aristide Dogariu.
Stochastic Polarimetry
An important outstanding problem in the statistical theory of electromagnetic radiation concerns the question of whether, and if so how, one can characterize its state of polarization. We have developed a number of methods and tools to both study the polarization of random fields and also to use the polarization characteristics of light to describe its interaction with complex media.
- Complex degree of mutual polarization
- Spatially-resolved polarimetry from multiply-scattering media
- Stochastic sensing polarimetry
Statistical Optics
The complex characteristics of random electromagnetic fields including intensity, phase distribution, state of coherence and polarization carry information about their propagation through and interaction with material systems. Properties of media such as refractive index, structural morphology, shape, etc. can be determined based on the measurable statistics of random electromagnetic fields.
At subwavelength scales, the statistical properties of optical fields are determined by both propagating and evanescent components and, as a result, characteristics such as first- and second-order statistics as well as the spectral density are all affected. Based on the coherence properties at subwavelength scales, new possibilities exist for surface and subsurface diagnostics. Manipulating the statistical properties of the radiation at these scales provides means for designing novel concepts for robust, integrated sensing techniques with resolution below the propagating light's wavelength.
- Variable coherence microscopy
- Statistical properties of optical near-fields
- Fluctuations in scattered light
Mechanical Action of Light on Matter
The idea of mechanical action of light originates in the corpuscular theory of light. Over the years, many models have been developed to describe the optical forces acting on matter and they all can be traced to a common source: the exchange of momentum between radiation and matter. Photons carry momentum and momentum conservation laws apply whenever atoms emit or absorb photons or whenever a beam of light changes its direction due to refraction or reflection.
Remarkable phenomena are consequences of these conservation laws. For instance, we have demonstrated that even in the highly symmetric circumstances of a sphere illuminated by circularly polarized light, transversal spin transport breaks this symmetry leading to an apparent shift of the sphere's location: the sphere can distinguish left from right.
Manipulating the polarization properties of electromagnetic fields has consequences for controlling the subwavelength behavior of optical forces and torques. Optical fields can also act on cells cytoskeletons and we reported recently that active control and guiding of cellular motility is possible as a result of optically induced torques.
Modeling Light-Matter Interactions
The interaction of light with complex, disordered materials is complicated and is not easy to treat analytically. Computers, however, are capable of performing many of the high-powered computations necessary to study light-matter interaction. We have performed extensive numerical studies utilizing the coupled dipole approximation (CDA). CDA code treats scatterers and optical inhomogeneities as a collection of discrete dipoles. An exciting light field will interact with each dipole and cause them to reradiate light. This newly radiated light excites other dipoles and the process repeats. Hence, each dipole is coupled to every other one. We use our CDA code to study the interaction of light with matter on the nano and microscales where many interesting phenomena occur.
Photonic Diagnostics of Random Media Group, 2009
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