Theoretical applied optics

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Optical fibers are the pipeline of the telecommunication. Researchers in both academics and industries are investigating all optic fiber networks that limiting the electro-optic conversion at the receiver and transmission ends. However as the bandwidth and speed exceed the data rate of 10GB/s per wavelength channel many of the existing fiber networks are not able to carry the information without suffering severe signal degradation. The limiting factors include fiber nonlinearity, polarization mode dispersion (PMD), polarization dependent loss (PDL), and chromatic dispersion (CD). Fiber nonlinearity describes the material's polarizability change by light's intensity and PMD is the polarization dependence of the light propagation speed. PDL is the polarization dependence of the signal attenuation and CD is the wavelength (color) dependence of the propagation speed. Furthermore those physical effects interact and their values are affected by environmental conditions like temperature, wind induced strain in field fibers. This proposal develops reliable simulation, emulation and compensation tools for the fiber communication network. The objective of this communication research is to advance the future all optic fiber networks. One of the nonlinear effect, namely stimulated Brillouin scattering (SBS), describing the coupling of acoustic phonon with the light, could also slow the signal propagation due to the nonlinear change of refractive index. Researches will be conducted in this aera of Brillouin slow light in conventional communication fibers as it is one of the key enabling technology as an optical buffer tuned by light itself. SBS effect in fiber can also be employed as a sensor since its Brillouin spectra are related to local temperature and strain. Due to fiber's flexability and tiny size the SBS based fiber sensors find vast area of applications, e.g., monitoring safty of large structures, fire alarms, oil and gas pipeline failure warnings, etc. The proposed study on sensing is to develop fast signal processing tools to enhance the accuracy of the temperature and strain measurements. This sensing research will have enormous practical impacts to the safty of our large civil structures (e.g., recent tragedy at highway overpass in Laval Quebec could be detected early).