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A 4 × 4 photonic switch matrix was designed, fabricated and characterized. The photonic switch matrix was based on microring resonator (MR) and was fabricated on relatively low-cost silicon-on-insulator (SOI). Independent wavelength channel switching was accomplished by thermo-optic tuning of the MRs through highly localized resistive micro-heaters. The device was fabricated using the relatively mature silicon fabrication technology. Waveguide patterns were defined with high definition eBeam lithography, etching was done in a reactive-ion etching chamber, and the top cladding SiO2 layer was deposited through plasma-enhanced chemical vapor deposition. Finally, resistive Nichrome micro-heaters were deposited locally directly above each MR to offer the dynamic tuning capability. The strong optical confinement offered by the high index contrast between silicon and SiO2 makes it possible to fabricate micrometer-sized MRs with acceptable optical power loss caused by the small bending radii. The MRs were designed with a uniform diameter of 10 µm to support a wide free spectral range. All waveguides have a design dimension of 450 nm × 250 nm to allow operation exclusively in the fundamental mode at the 1.55 µm wavelength. A FSR of 18 nm with a spectral linewidth of 0.1 nm were observed for the fabricated MRs offering high wavelength selectivity. The device exhibits virtually no thermal crosstalk between adjacent channels, showing no output peak wavelength shift at 0.01 nm wavelength measurement precision by thermally tuning an adjacent MR with electric current as high as 7 mA, which is equivalent to about 2.5 nm in resonance wavelength tuning. The device showed a tuning delay time of about 1 ms. The overall bare chip size of the device is 20 mm × 4 mm. We demonstrated through this work a wavelength selective photonic switch device using low-cost SOI technology that is compact and easy to fabricate. It shows high potential for further development into high port-count photonic switch matrix.

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The last decade witnessed a wild growth of the Internet traffic, promoted by bandwidth-hungry applications such as Youtube, P2P, and VoIP. This explosive increase is expected to proceed with an annual rate of 34% in the near future, which leads to a huge challenge to the Internet infrastructure. One foremost solution to this problem is advancing the optical networking and switching, by which abundant bandwidth can be provided in an energy-efficient manner. For instance, with Wavelength Division Multiplexing (WDM) technology, each fiber can carry a mass of wavelengths with bandwidth up to 100 Gbits/s or higher. To keep up with the traffic explosion, however, simply scaling the number of fibers and/or wavelengths per fiber results in the scalability issue in WDM networks. One major motivation of this dissertation is to address this issue in WDM networks with the idea of waveband switching (WBS). This work includes the author's study on multiple aspects of waveband switching: how to address dynamic user demand, how to accommodate static user demand, and how to achieve a survivable WBS network. When combined together, the proposed approaches form a framework that enables an efficient WBS-based Internet in the near future or the middle term. As a long-term solution for the Internet backbone, the Spectrum Sliced Elastic Optical Path (SLICE) Networks recently attract significant interests. SLICE aims to provide abundant bandwidth by managing the spectrum resources as orthogonal sub-carriers, a finer granular than wavelengths of WDM networks. Another important component of this dissertation is the author's timely study on this new frontier: particulary, how to efficiency accommodate the user demand in SLICE networks. We refer to the overall study as the resource management in multi-granular optical networks. In WBS networks, the multi-granularity includes the fiber, waveband, and wavelength. While in SLICE networks, the traffic granularity refers to the fiber, and the variety of the demand size (in terms of number of sub-carriers).

Organic π-conjugated molecules and materials with large real parts and small imaginary parts of the third-order polarizability are of great interest for all-optical switching applications. In this dissertation, we use quantum-chemical and molecular-dynamics approaches to investigate the structure-property relationships that influence the nonlinear optical properties of π-conjugated molecules and materials. We begin with an overview of nonlinear optics, focusing in particular on the electronic properties of linear π-conjugated systems and some of the important problems that have limited device applications of these molecules to date. This is followed by a brief review of the computational methods employed in these studies. We then turn to the main results of the dissertation. Chapter 3 describes the structural dependence of the transition dipole moment between the first two polymethine excited states. Chapter 4 discusses the relationship between BLA, which depends on the geometric structure, and BOA, which probes electronic structure. Chapter 5 describes the benchmarking of computational methods to describe the symmetry-breaking of long polymethines and preliminary evidence regarding the role of vibrational modes in symmetry-breaking. Chapter 6 explains the negative third-order polarizability of tetraphenylphosphate and analogous systems. Chapter 7 focuses on molecular-dynamics studies of polymethine aggregation, particularly the relationships between chemical structure and the geometric and electronic structures of aggregates. Finally, Chapter 8 provides a synopsis of the work and discussion of further directions.

Exciton-polaritons in semiconductor microcavities have been studied intensely, both with respect to their intriguing fundamental physical properties and with respect to their potential in novel device designs. The latter requires ways to control polaritonic systems, and all-optical control mechanisms are considered to be especially useful. In this talk, we discuss and review our efforts to control the polariton density, utilizing optical four-wave mixing instabilites, and the spin or polarization textures resulting from the optical spin Hall effect. Both effects are readily observable in the cavity's far-field emission, and hence potentially useful for optoelectronic and spinoptronic device applications.

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