Research

Research Areas

Our research is in the area of optical microsystems. Some details of specific projects are given below.
Programmable Imaging with Optical MEMS - This research has developed a new paradigm of photographic imaging, which we call “programmable” imaging.  They active element in our imaging design is a micro-electrical-mechanical system (MEMS) mirror array, consisting of a configuration of mirrors that are capable of changing state thousands to millions of times per second.  These mirror allowing for specific defined sampling of the object image.  By controlling the tilt of the mirror and extracting a single pixel from each mirror state, different views of the object are possible.  This work is performed in collaboration with R. Andrew Hicks (Drexel, Mathematics) and supported through NSF #IIS-0413012.

More information can be found on this poster

Precancerous Detection using White Light Spectroscopy - In this research area, we are developing an on-chip optical spectrometer directly on fiber which can be employed at the end of a minimally-invasive endoscope for in-vivo optical examination of cancerous and pre-cancerous cells.  The goal of the proposed endoscopic spectrometer probe is to optically identify the cellular size variations, targeting specific biopsy locations thereby increasing the sensitivity and accuracy of the biopsy procedure.  The pre-cancerous cells will demonstrate a shape anisotropy compared to the healthy cells, resulting in a diffuse reflectance signature as detected on a GaAs detector array.  The signature is a product of wavelength and diffuse reflectance angle, necessitating a second wavelength filter stack on the detector path of the spectrometer chip.  A white light LED is used as an emitting source, which is filtered through a holographic polymer dispersed liquid crystal stack, emitting specific wavelengths of probe light and thereby enabling fluorescence and diffuse reflectance characterization.  The reflected light (or emitted light for fluorescence) is filtered for wavelength purity and subsequently focuses and collected onto an optical detector array.  An array is used to measure the angular dispersion of the reflectance for cellular size distribution analysis.  This effort is in collaboration with Adam Fontecchio (Drexel, ECE), Bahram Nabet (Drexel, ECE), and Sree Murthy (Drexel, Medical School) and using support from NSF #ECCS-0621811.

More information can be found on this poster and this poster

Diffuse Optical Communication - This research effort applies MIMO techniques, typically used in the RF domain, in the optical domain to overcome power limitations and increase the spectral capacity and data rate in diffuse optical communication links.  Diffuse FSO local area networks have several potential advantages over conventional radio frequency networks. Beyond the potential for increased data rates, the optical spectrum offers a large unregulated bandwidth capacity potential. Diffuse optical networks are not limited by electromagnetic interference due to the physical constraints of the infrared (IR) medium.  Therefore, they are easier to deploy (since they do not require frequency planning) and are more secure than their RF counterparts (since IR radiation is confined within the physical boundaries of the coverage area). However, even with these potential advantages over RF systems, current academic and commercial diffuse optical local area networks still provide lower data rates than RF local area networks, due to the optical power decreasing greatly as the signal diffuses from a medium.  This work is in collaboration with Kapil Dandekar (Drexel), using support from NSF #ECS-0524200 and the U.S. Army CERDEC.

More information can be found on this poster

Ink jet Printing Polymer - We are investigating the ink-jet printing of polymers. We are examining two applications with the ink jet printing. The first is printing conductive polymer for transparent, flexible antennas on non-traditional substrates (i.e. fabric, transparencies, stickers, etc.). We anticipate demonstrating how conformal antenna arrays can be fabricated using this technique. This work is in collaboration with Dr. Kapil Dandekar (Drexel) and Dr. Adam Fontecchio, using support from the U.S. Army CERDEC.

The second application is to create inkjet printed optical structures. Our initial work has been using polymer to create optical waveguides

More information can be found on this poster

Magnetic Particle Locomotion - In collaboration with Gary Friedman (Drexel, ECE) and Allon Guez (Drexel, ECE) we have demonstrated through simulation and through experimentation, the locomotion of two spheres in a uniform magnetic field.  The key to this phenomenon is the interaction force between the spheres.  Control theory is employed to formulate the problem of controllability of two microparticles in fluids via magnetic field. We demonstrate that a uniform external magnetic field of varying direction and magnitude provides complete local state controllability of two particles over a magnetized substrate.  We propose that such an approach may improve manipulation and assembly of microparticles in fluids, for applications including bio-delivery, magnetic locomotion, and micro self assembly.
Assembly Automation of Opto-Electronic Components - In collaboration with Allon Guez, we are developing an automation process for the assembly, manufacturing, and packaging of optical microsystems using advanced device specific optical power models as well as intelligent control theory to yield high performance, low cost packaging.  A priori device and process knowledge are exploited in on-line control loops to align fibers and components in a near optimal configuration to maximize power transmission.  Our technique incorporates the materials and mechanics in order to position the components and devices, exerting forces on the various degrees of freedom before, during, and after alignment so that the optical signal is positioned for maximum transmission in a robust manner.  Using the model based control process, we are presenting a new paradigm for photonic automation.  Our technique will increase the system performance and efficiency of the automation process, while decreasing the cost of optical microsystems.  This technique will employ existing capital equipment infrastructure (from semiconductor and industrial automation) and increase the system performance in terms of bit error rate (BER), signal-to-noise ratio (SNR), insertion loss, crosstalk, and coupling.  As device and system designs become more complex, the advantages of our technique will be magnified.

More information can be found on this poster