This page is the starting point for what will hopefully be a somewhat interactive description of my research interests. My field of research may be broadly described as ‘classical optics’, which is the study of the wave nature of light. An overview of the wave nature of light may be found in the following blog posts (part I, part II,part III, part IV), for those not familiar with the concept; this overview will provide some background in understanding the topics below.
My specific interests fall into four broad categories, though it should be noted that there is a surprising amount of overlap between the different categories:
- Inverse Problems: This is the study of systems such as the spectacularly successful CAT scan (computed axial tomography). A discussion of CAT scans is found on my blog here; a general introduction to inverse problems can be found here. Computed tomography is performed with X-rays, which travel on straight line paths through the human body, absorbed but not deflected; however, researchers are interested in using non-ionizing radiation for medical imaging, for perhaps obvious reasons. Visible light is strongly scattered by the human body and this makes the problem of imaging much more difficult; my research focuses on developing novel medical imaging techniques which incorporate scattering/diffraction effects.Closely related to inverse scattering is the physics of invisibility and “cloaking” devices. The hypothetical existence of invisible objects implies that the inverse scattering problem is non-unique: if invisible objects exist, their structural properties cannot be determined by scattering experiments! I am involved in the study of different forms of invisibility and their implications for inverse problems.
- Light Interaction on the Nanoscale: There is much recent interest in investigating the interaction of light with objects much smaller than the wavelength (typically objects with size comparable to a nanometer). The field was reinvigorated in 1998 by the observation of extraordinary optical transmission (EOT), in which more light is transmitted through an array of subwavelength-size holes than expected according to traditional optical theory. This EOT has been attributed to the presence of surface waves known as plasmons; I discuss some of the basics of EOT in a post here. My research has involved the study of the consequences of EOT, in particular its use in developing “super compact disc” systems and its use in modifying the coherence properties of light.
- Coherence Theory and Propogation of Partially Coherent Beams: It has been shown that beams with randomly fluctuating phase fronts have some advantages over their fully coherent counterparts, in such applications as propagation through turbulence and reduction of speckle effects. I have been engaged in the study of partially coherent beam propagation through atmospheric turbulence, with the goal of developing improved optical communications systems. In addition, I am involved in studying how the statistical properties of light (its coherence) affects the general behavior of light.
- Singular Optics: At points where the intensity (brightness) of a wavefield is zero, the phase of the wavefield is undefined and said to be singular. Around these zero points, the field tends to ‘circulate’, and they are typically referred to as ‘optical vortices’. Fields which contain optical vortices possess many interesting mathematical and physical properties, and I have been doing extensive research on the properties and applications of such wavefields. An introduction to singular optics can be read here.