Silicon Photonics for Chemical Sensing and Spectroscopy, Diagnosis and Therapy
May 21, 2012
from 02:30 PM to 04:00 PM
|Where||ENGR. IV Bldg. Maxwell Room 57-124|
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Advisor: Prof. Bahram Jalali
Silicon Photonics is a research area that utilizes silicon as the optical medium. It has been attracting a lot of research interests in past few years. Due to the mature silicon fabrication industry, Si is a low cost and well understood material. The tight optical confinement in Si also makes it a promising candidate for high speed on-chip interconnects. However, almost all literature results are demonstrated in the optical communication window. We believed that optical communication is not the only area where silicon photonics will have an impact. My research is to explore the new capabilities of silicon. In this talk, a number of new applications of silicon photonics, ranging from chemical sensing and spectroscopy to diagnosis and therapy, will be introduced.
In the first part, I will introduce a new class of photonic devices based on periodic stress fields in silicon that enables second-order nonlinearity and achieves quasi-phase matching in silicon simultaneously – periodically-poled silicon (PePSi). This adds the periodic poling technology to silicon photonics and allows the excellent crystal quality and advance manufacturing capability of silicon to be harnessed for devices based on the linear electro-optic effect and other second-order nonlinear effects. As an example of utility of the PePSi technology, efficient mid-wave infrared generation can be realized though difference frequency generation which is useful for a wide range of applications such as gas sensing and spectroscopy. In this part, I will also present a new type of tunable dispersive device, which overcomes the limitations of operational bandwidth, total dispersion and large spatial footprint by leveraging the large modal dispersion of a multimode waveguide in combination with the angular dispersion of diffraction gratings to create chromatic dispersion on both multimode fibers and silicon waveguides and demonstrate its ability for single-shot, time-wavelength absorption spectroscopy.
In the second part, the application of using porous silicon nanoparticles (PSiNPs) for in vivo cancer diagnosis and therapy will be presented. PSiNPs are attractive carriers for targeted drug delivery in nanomedicine. For in vivo applications, the biodegradation property of PSiNPs provides a pathway for their safe clearance from the body. Particles sizes of 80 – 120 nm are of particular interest, however, the biodegradability rate of such particles is often too fast, which limits particles’ in vivo half-life and potentially reduces their delivery efficiency. In this part, I focus on the degradation of nano-scale particles and study the effect of both thermal oxidation and silica coating on the stability of PSiNPs in phosphate buffered saline solution (a close mimic of a basic biological fluid) for applications in drug delivery or flow cytometry.
Nick, Kam-Yan Hon received his MPhil degree in Electrical and Computer Engineering from Hong Kong University of Science and Technology in 2007. During his Master studies, he worked on high speed silicon optical modulators. From 2007, he is pursuing his Ph.D. in UCLA. His research activities are presently in the area of silicon photonics for chemical and biological applications.