Nonlinear effects in photonic devices and systems

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Nonlinear effects in photonic devices play an important role in the design of fiber optic networks, imaging systems and microcavites. In applications such as fiber optic networks, these effects are detrimental whereas they can be beneficial in imaging systems and microcavities. This proposal develops techniques to mitigate them when they cause problems and to enhance them when they provide benefits. ***A fiber-optic network forms the backbone of the internet and as demand for video services grows, the capacity of this network must increase. Successful mitigation of the linear effects using the equalizers, transmission speeds have increased from several Mb/s to hundreds of Tb/s. Now the fundamental impediments to increases in capacity and reach that will be required to satisfy the future demands are those generated by nonlinear effects. In this proposal, digital and optical techniques will be developed to mitigate these effects in single mode and few mode fibers. We will also explore the possibility of constructing multiple-input multiple-output systems with inexpensive light sources and direct detection receivers. The subscribers have the potential to greatly reduce the cost per bit of fiber optic networks.***Nonlinear imaging techniques are used for identification of molecules in biomedical applications. When a pump wave and a Stokes wave are incident on a sample, the degree of amplification of the Stokes wave provides the fingerprint by which the molecule can be identified. Typically, direct detection receivers are used in imaging systems which do not have information on the phase. We propose to combine the nonlinear imaging with coherent technology so that the phase of optical signal is available at the receiver. This enables construction of a 3-D vibrational image of a molecule. Coherent detection enables the back propagation techniques akin to those developed for fiber optic systems. These techniques have the potential to remove unwanted background and improve the quality of the image. ***Optical microcavities have been used for Raman lasers and sensing applications. In this proposal, we will investigate the nonlinear effects on optical modes in microcavity. The microcavity supports acoustic modes and the study of acousto-optic interaction in microcavity could lead to interesting new applications, such as acoustic lasers. We will explore the possibility of constructing ultralow threshold Raman lasers and acoustic lasers by optimizing the device geometry. ***As suggested by some of the proponent's previous/existing interactions with industrial partners, Canadian companies in the communications, sensing and biomedical fields could benefit from the techniques developed in this program. Furthermore, the students trained in the program will develop highly transferable skills that will be of interest not only to companies that are active in these fields, but other high technology companies, too.**