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Silicon Photonics for chemical sensing and spectroscopy, diagnosis and therapy

  • Author(s): Hon, Kam Yan
  • Advisor(s): Jalali, Bahram
  • et al.

Silicon Photonics has been attracting a lot of research interests in past few years. However, almost all literature results are demonstrated in the optical communication window. We believe that optical communication is not the only area where silicon photonics will have an impact. In this talk, a number of new applications of silicon photonics, ranging from chemical sensing and spectroscopy to diagnosis and therapy, will be introduced.

First, 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 or 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 for applications such as gas sensing and spectroscopy.

Second, I will 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 multimode fibers and silicon waveguides. I will characterize the devices' dispersion, and demonstrate its ability for single-shot, time-wavelength absorption spectroscopy.

Third, 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 will also present a study on 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).

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