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Optical interconnects are important to the future development of microelectronics. Volume grating couplers (VGCs) provide a compact, efficient coupling mechanism that is compatible with microelectronics fabrication processes. In this dissertation, some of the performance characteristics of VGCs are investigated. Also, integration of VGCs with Sea of Polymer Pillars (SoPP), an emerging high-density input/output interconnect technology, is demonstrated and its performance quantitatively investigated. First, the polarization-dependent performance of VGCs is analyzed, and the design constraints for achieving high-efficiency polarization-dependent and polarization-independent VGCs are examined. The effects of loss on VGC performance are also presented. Then, the wavelength response of VGCs and its dependence on grating parameters is quantitatively examined. Experimental demonstrations of polarization-dependent and polarization-independent VGCs are then presented. Finally, a VGC integrated with a SoPP is demonstrated and its performance characterized.

Integrated optics as a platform for signal processing offers significant benefits such as large bandwidth, low loss, and a potentially high degree of reconfigurability. Silicon (Si) has unique advantages as a material platform for integration, as well as properties such as a strong thermo-optic mechanism that allows for the realization of highly reconfigurable photonic systems. Chapter 1 is devoted to the discussion of these advantages, and Chapter 2 provides the theoretical background for the analysis of integrated Si-photonic devices. The thermo-optic property of Si, while proving extremely useful in facilitating reconfiguration, can turn into a nuisance when there is a need for thermally stable devices on the photonic chip. Chapter 3 presents a technique for resolving this issue without relying on a dynamic temperature stabilization process. Temperature-insensitive (or “athermal”) Si microdisk resonators with low optical loss are realized by using a polymer overlayer whose thermo-optic property is opposite to that of Si, and TiO2 is introduced as an alternative to polymer to deal with potential CMOS-compatibility issues. Chapter 4 demonstrates an ultra-compact, low-loss, fully reconfigurable, and high-finesse integrated photonic filter implemented on a Si chip, which can be used for RF-photonic as well as purely optical signal processing purposes. A novel, thermally reconfigurable reflection suppressor is presented in Chapter 5 for on-chip feedback elimination which can be critical for mitigating spurious interferences and protecting lasers from disturbance. Chapter 6 demonstrates a novel device for on-chip control of optical fiber polarization. Chapter 7 deals with select issues in the implementation of Si integrated photonic circuits. Chapter 8 concludes the dissertation.

The study and applications of surface plasmon polaritons (SP) – also known as plasmonics – has attracted the interest of a wide range of researchers in various fields such as biology, physics, and engineering. Unfortunately, the large propagation losses of the SP severely limit the usefulness of plasmonics for many practical applications. In this dissertation a new wave guiding mechanism is proposed in order to address the large propagation losses of the plasmonic guides. Possible applications of this guiding scheme are also investigated. The proposed hybrid plasmonic waveguide (HPWG) consists of a metal layer separated from a high index slab by a low index spacer. A detailed analysis is carried out to clarify the wave guiding mechanism and it is established that the mode guided by the HPWG results from the coupling of a SP mode and a dielectric waveguide mode. A two dimensional HPWG is proposed and the effects of various parameters on the HPWG performance are analyzed in detail. This structure offers the possibility of integrating plasmonic devices on a silicon platform. The proposed waveguide supports two different modes: a hybrid TM mode and a conventional TE mode. The hybrid TM mode is concentrated in the low index layer, whereas the conventional TE mode is concentrated in the high index region. This polarization diversity is used to design a TM- and a TE-pass polarizer and a polarization independent coupler on a silicon-on-insulator (SOI) platform. Moreover, the performance of a HPWG bend is investigated and is compared with plasmonic waveguide bends. The proposed devices are very compact and outperform previously reported designs. The application of HPWG for biosensing is also explored. By utilizing the polarization diversity, the HPWG biosensor can overcome some of the limitations of plasmonic sensors. For example, unlike plasmonic sensors, the HPWG biosensor can remove the interfering bulk and surface effects.

As a subset of quantum optics, single photons are one of the competing physical resources for quantum information processing. When used as carriers of quantum information, they have no equal. For the processing of quantum information, single photons have proven difficult to scale beyond the order of ⇠ 10 photons. The lack of single-photon-level interaction has led to creative approaches which rely on postselection to filter the possible measured outcomes to those which appear as though interaction occurred. This approach of post-selection leans heavily on the ability to not only generate but also detect scores of single photons simultaneously and with near perfect efficiency. Our work relaxes the emphasis which has been placed on single photons for quantum information processing to that of states with, in principle, an arbitrary number of photons. Central moment expectations on two-mode squeezed states are shown to exhibit post-selection behavior which reflects the single-photon counterpart. These measures are proven to be robust to loss and return entangled state statistics on average. With naive estimation of the central moment, states with ~ 20 modes are within reach with current technology, closing the gap between quantum states which can and cannot be classically simulated. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Wong, Chi Yan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 134-149). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Cheng, Zhenzhou. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Recent advances in computing technology have highlighted deficiencies with electrical interconnections at the motherboard and card-to-backplane levels. The CPU speeds of computing systems are drastically increasing with on-chip local clock speeds expected to approach 6 GHz by 2010. Yet, card-to-backplane communication speeds have been unable to maintain the same pace. At speeds beyond a few gigahertz the implementation of electronic interconnects gets increasingly complex, thus, alternative optical interconnection techniques are being extensively researched to relieve the expected CPU to data bus bottleneck. Despite the advantages afforded by optical interconnects there are still demands for improved packaging, enhanced signal tapping, and reduced cost expenditures. In this dissertation, we present a novel array waveguide evanescent coupling (AWEC) technology for card-to-backplane applications. The interconnection scheme is based on waveguide directional coupling between a backplane waveguide and a flexible waveguide connected to the access card or daughter board. To gain access to the shared bus media, coupling of evanescent waves is exploited to tap optical signals from the backplane waveguide to the corresponding card waveguide. The approach results in the elimination of micro-mirror out of plane deflectors and local waveguide termination obstacles present in other reported optical interconnect schemes. Most importantly, the AWEC method can yield efficient multi-drop bus architectures, not possible through free-space, fiber, or traditional guided wave approaches, that only achieve point-to-point topologies. The AWEC concept for optical interconnection was introduced through coupled mode theory, numerical simulations and BeamPROP aided CAD models. Subsequent experimental waveguide analysis was performed and shown to reasonably agree with the simulation results. Likewise, a high-resolution, cost-effective, and rapid prototyping approach for AWEC fabrication has been formulated. Significantly, when compared to other soft lithographic methods, the novel vacuum assisted microfluidic (VAM) technique results in improved waveguide structures, polymer background residue elimination and lower propagation losses. Moreover, experimental results show that our evanescent coupling approach facilitates high-speed coupling between card and backplane waveguides at speeds of 10 Gbps per channel; currently limited only by our testing electronics. In addition, satisfactory eye diagram performance comparable to that of a conventional fiber link, was also observed for the AWEC, alluding to possible aggregate speeds of 100 Gbps. Similarly, we implemented an elementary AWEC shared bus architecture and demonstrate a microprocessor-to-memory interconnect prototype through the proposed AWEC link. Notably, we expect that the AWEC scheme will be significant for high-speed optical interconnects in advanced computing systems.

A tunable guided-wave optical filter that performs spectral slicing at the 1530nm wavelength regime in Ti:LiNbO3 was proposed and fabricated. It is aimed at minimizing crosstalk between channels in dense wavelength division multiplexing (DWDM) optical network applications. The design utilizes a sparse grating allowing the selection of equally spaced channels in the frequency domain. Between selected channels, equally spaced nulls are also produced. The sparse grating is formed by using N coupling regions with different lengths along the direction of propagation of light in the waveguide, generating N-1 equally spaced nulls between adjacent selected channels. The distance between the centers of adjacent coupling regions is kept constant. The filtering is based on codirectional polarization coupling between transverse electric (TE) and transverse magnetic (TM) orthogonal modes in a waveguide through an overlay of strain-induced index grating, via the strain-optic effect. Two types of devices were fabricated. In the first type, the sparse gratings were produced on straight channel waveguides. Selected channels emerge from the device in a polarization state orthogonal to the input and a polarizer is needed to observe the filtered light. For the second type, an asymmetric Mach-Zehnder interferometer configuration was used to eliminate the need of the polarizer at the output, and yields an output response that is polarization independent. Both types of devices were fabricated on x-cut y-propagating LiNbO3 substrates, with N = 6 strain-induced coupling regions. The single mode channel waveguides were formed by Ti diffusion. Electrode patterns centered about the optical waveguide were defined by liftoff. In the straight channel devices, insertion loss was less than 2.5 dB on a 43 mm sample. The 3-dB channel bandwidth of the selected channels is approximately 1.0 nm. Devices were tuned thermally as well as by voltage application to surface electrodes resulting in tuning rates of 1.0 nm/oC and 0.04148 nm/V, respectively. In the polarization independent device the insertion loss for the phase-matched wavelength was 5.3 dB on a 53 mm long chip. The 3-dB bandwidth was also ~1.0 nm and the thermal tuning rate 1.0 nm/oC. The experimental results are in good agreement with design theory.

Thesis (Ph. D.)--School of Electrical and Computer Engineering, Georgia Institute of Technology, 2004. Directed by James D. Miendl. / Vita. Includes bibliographical references.