Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Microfiche copy available in Archives and Engineering. / Includes bibliographical references. / M.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Arthur Douglas Fisher. / Ph.D.

Silicon photonics has emerged in recent years as one of the leading technologies poised to enable penetration of optical communications deeper and more intimately into computing systems than ever before. The integration potential of power efficient WDM links at the first level package or even deeper has been a strong driver for the rapid development this field has seen in recent years. The integration of photonic communication modules with very high bandwidth densities and virtually no bandwidth-distance limitations at the short reach regime of high performance computers and data centers has the potential to alleviate many of the bandwidth bottlenecks currently faced by board, rack, and facility levels. While networks on chip for chip multiprocessors (CMP) were initially deemed the target application of silicon photonic components, it has become evident in recent years that the initial lower hanging fruit is the CMP's I/O links to memory as well as other CMPs. The first chapter of the thesis provides more detailed motivation for the integration of silicon photonic modules into compute systems and surveys some of the recent developments in the field. The second chapter then proceeds to detail a technical case study of silicon photonic microring-based WDM links' scalability and power efficiency for these chip I/O applications which could be developed in the intermediate future. The analysis, initiated originally for a workshop on optical and electrical board and rack level interconnects, looks into a detailed model of the optical power budget for such a link capturing both single-channel aspects as well as WDM-operation-related considerations which are unique for a microring physical characteristics. The holistic analysis for the full link captures the wavelength-channel-spacing dependent characteristics, provides some methodologies for device design in the WDM-operation context, and provides performance predictions based on current best-of-class silicon photonic devices. The key results of the analysis are the determination of upper bounds on the aggregate achievable communication bandwidth per link, identifying design trade-offs for bandwidth versus power efficiency, and highlighting the need for continued technological improvements in both laser as well as photodetector technologies to allow acceptable power efficiency operation of such systems.The third chapter, while continuing on the theme silicon photonic high bandwidth density links, proceeds to detail the first experimental demonstration and characterization of an on-chip spatial division multiplexing (SDM) scheme based on microrings for the multiplexing and demultiplexing functionalities. In the context of more forward looking optical network-on-chip environments, SDM-enabled WDM photonic interconnects can potentially achieve superior bandwidth densities per waveguide compared to WDM-only photonic interconnects. The microring-based implementation allows dynamic tuning of the multiplexing and demultiplexing characteristic of the system which allows operation on WDM grid as well device tuning to combat intra-channel crosstalk. The characterization focuses on the first reported power penalty measurements for on-chip silicon photonic SDM link showing minimal penalties achievable with 3 spatial modes concurrently operating on a single waveguide with 10-Gb/s data carried by each mode. The chapter also details the first demonstration of WDM combined with SDM operation with six separate wavelength-and-spatial 10-Gb/s channels with error free operation and low power penalties. The fourth, fifth, and sixth chapters shift in topic from the application of silicon photonics to communication links to the evolving use of silicon waveguides for nonlinear all-optical processing. The unique tight mode confinement in sub-micron cross-sections combined with the high response of silicon have motivated the development of four-wave mixing (FWM)-based processing silicon devices. The key feature of the silicon platform for these nonlinear processing platforms is the ability to finely and uniformly control the dispersive properties of the optical structures in a way that enables completely offsetting the material dispersion and achieve dispersion profiles required for effective parametric interaction of waves in the optical structures. Chapter four primarily introduces and motivates nonlinear processing in communication applications and focuses on recent achievements in non-silicon and silicon FWM platforms. Chapter five describes some of the author's contributions on parametric processing of high speed data in silicon nonlinear devices, with first of a kind demonstrations of wavelength conversion of 160-Gb/s optically time division multiplexed (OTDM) data as well as the wavelength-multicasting of a 320-Gb/s OTDM stream. The chapter then details a methodical characterization and demonstration of several record wavelength conversion experiments of data in silicon with 40-Gb/s data wavelength-converted across more than 100 nm with only 1.4-dB of power penalties as well as the wavelength and format conversion of 10-Gb/s data across up to 168 nm with sensitivity gains stemming from the format conversion of about 2 dB and a residual conversion penalty of only 0.1 dB, achieved by implementing an improved experimental setup. Both experiments highlight the performance uniformity of the conversion process for a wide range of probe-idler detuning settings, showcasing the silicon platform's unique broadband phase matching properties. The sixth chapter presents a slight shift in motivation for parametric processing from traditional telecom-wavelength applications to functionalities developed targeting mid-IR operation. Parametric-processing in the silicon platform at long wavelengths holds large potential for performance improvements due to the elimination of two-photon absorption in silicon at long wavelengths as well as silicon's dispersion engineering capabilities which uniquely position the silicon platform for effective phase matching of significantly wavelength detuned waves. Four-wave mixing signal generation and reception at mid-IR wavelengths are attractive candidates for tunable flexible operation with modulation and detection speeds which are currently only available at telecom wavelengths. With this vision in mind, several contributions detailing extension of FWM functionalities in silicon to operate at wavelengths close to 2 μm with performance equivalent to much smaller detuning setting measurements. The contributions detail the experimental demonstration of the first silicon optical processing functionalities achieved at such long wavelengths including the wavelength conversion and unicast of 10-Gb/s signals with up to 700 nm of probe-idler detuning, the combined two-stage 10-Gb/s FWM-link in which both data generation and detection at 1900 nm is facilitated by parametric processing in silicon with only 2.1-dB overall penalty, the first ever 40-Gb/s receiver at 1900 nm based on a FWM stage for simultaneous temporal demultiplexing and wavelength conversion, and lastly, the demonstration of a 40-Gb/s FWM-link operation with only 3.6 dB of penalty. The chapter concludes with a short discussion on possible extensions to enable silicon parametric processing at even longer wavelengths targeting the mid-IR spectral transmission window of 3-5 μm.

This research addresses challenges in two major applications, both related to photonic cognitive sensing. The first part, “Implantable Photonic Nano-Probe Detectors for Neural Imaging”, focuses on imaging system in the neural sciences field. The second part, “Advanced Control System for Optical Data Communications”, covers embedded low power control systems for optical communications. Implantable Photonic Nano-Probe Detectors for Neural Imaging This first part address the problem of simultaneous and real-time monitoring of dense brain neural activity, with the capability of cellular resolution and cell-type specificity included. For decades, electrophysiology has been the “gold standard” for the recording of neural activity. Despite recent advances, electrophysiology techniques can typically monitor fewer than 100 neurons simultaneously, due to the practical limits of electrode density. Additionally, the ability of direct monitoring specific cell types is not possible here. With the introduction of a growing panel of fluorescent optical reporters for brain function mapping, optical microscopy techniques have demonstrated the ability to track the activity of hundreds of neurons simultaneously in a much less invasive manner but with high spatial resolution, low-to-moderate temporal resolution and cell-type specificity. Unfortunately, only superficial layers of the brain can be imaged by free-space microscopy, due to the intrinsic light scattering and absorption limitation in brain tissue. To allow optical fluorescence imaging of deeper layers of the brain with proper a signal-to-noise ratio, a dense and scalable 3-D lattice of photo emitter and detector pixels (E-Pixels and D-Pixels, respectively) must be distributed on shanks for possible insertion into the brain. The 3-D lattice (combined fluorescent optical reporters) is expected to give an activity image of a very large neural population at an arbitrary depth in the brain. This work presents the design and implementation of the aforementioned 3-D photo- detectors (D-Pixels), associated with data processing and readout circuitries, for the future assembly of a probe-based system for functional imaging of neural activity. One of the main challenges of producing a probed-based version of a fluorescence microscope is the rejection of the light used to excite the fluorescent reporters. This is commonly done in the spectral domain with band-pass filters for free-space microscopy. However, these filters are not implementable with the proper optical density at the probe scale. The probe-based photo-detectors must be capable of rejecting the excitation light and capturing only the fluorescent response without the use of optical filters. Integrated Geiger-mode single-photon avalanche diodes (SPADs) are used as the sensing devices, which provide the ability to capture low fluorescence signals, fast response in the time domain, and direct digital readout. By engineering narrow E-Pixels angular-excitation fields and overlapping them with the narrow D-Pixels detection fields, fluorescent sources can be spatially localized. The detectors are embedded into four ultra-thin implantable shanks, associated with data processing units and readout circuits, all forming the photonic nano-probe detectors (also referred to as “D-Pixels Camera Chip (DCC)”). The shanks have dimensions of 110um×50um each, with 100 pixels along a shank (a total number of 400 pixels), distributed over 3mm length. The data generated by the photonic nano-probe detectors, is serially streamed out at a rate of 640Mbps, for offline analysis and image reconstruction. The photonic nano-probe detectors are fabricated in a conventional CMOS 0.13um technology. This part of the thesis first proposes and develops the architecture of the photonic nano-probe detectors. The challenges of designing high density, ultra-thin probes with the aforementioned form factor, fabricated in CMOS 0.13um technology is also discussed. Secondly, the design and implementation of testability and debugging options are mentioned, as playing an important role in achieving research goals. Last the design of lab experimental setups is presented and as well as the measurement results of the photonic nano-probe detectors. Experimental results indicate on achieving the crucial key features of the research work, the capability of rejecting the excitation light and capturing only the fluorescent decay response without the use of optical filters. Additionally, the results show that the photonic nano-probe detectors can precisely localize and map into a 2-D image, a light source within a pixel resolution.   Advanced Control System for Optical Data Communications The second part of the thesis focuses on the problem of initialization and temperature stabilization of silicon photonic (SiP) devices, with focus on dramatic power reduction of the power consumption. While microelectronics technology continues growing in scale, bandwidth, and integration of multiple systems on a single silicon die, the traditional electrical interconnects become the speed bottleneck in high-performance data communication systems. On the other hand, silicon photonics offers a promising platform for integration and manufacturing of photonics devices for high speed data transfer applications, such as access networks, supercomputers, chip-to-chip interconnects, and data centers. Additionally, the high index contrast of silicon platform and its compatibility with CMOS technologies, gives rise to integration of high speed, power efficient silicon photonic interconnects and most innovative CMOS technologies. Micro-ring resonators (MMRs), which are important building blocks is many silicon photonics applications, became attractive devices in many optical communication systems. This is due to their wavelength tuning ability, low power consumption and small footprint. However, temperature changes in their environment will shift their resonance from the desired point (due to high thermo-optical coupling in silicon), leading to performance degradation of the optical link. Compensating the degradation in performance can be directly translated to an excess in overall power consumption of the link, which will be critical in high-speed optical data communication systems. This work develops and demonstrates an ultra-low power control system, for initialization and temperature stabilization of MMRs. It utilizes an integrated heater, to thermally tune and lock the resonator to the desired wavelength. Traditional feedback loops rely on tapping a portion of the optical signal with the use of integrated photodiodes. They lock on the desired wavelength by sensing the maximum signal intensity, observed by the photodiode. The suggested control system in this work is based on an analog control system and utilizes the photo-conductance effect of doped-resistive heaters, to sense the optical power through the micro-ring. This part of the thesis first develops a VERILOG-A model for the photo-conductance effect of the doped-resistive heater. This enables the integration of the heater’s model with the proposed control circuits, into a circuit design simulator. Secondly, an architecture for the control system is proposed and developed, which includes fundamental electronic circuits with the aforementioned heater’s model. For the purpose of circuit level simulations, a design methodology is developed, which is based on semi-ideal models for the electronic building blocks. Then a circuit level simulator is used to simulate and evaluate the performance of the control system. Last, the proposed system is implemented with the use of commercial discrete electronic components, all connected on a custom designed printed circuit board (PCB). Simulations of the control system indicate an initialization time less than 160us, and maximum locking voltage error of 1.8%. The obtained dynamic energy consumption is ED=85 fJ/bit/oC for bit rate of 20Gbps. Though the control system is targeted for MRRs, it can be easily expanded to control other PIC devices.

Chan Sze-wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.vi / Table of contents --- p.vii / List of figure --- p.xi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- Optical non-linearity of fiber and semiconductor optical amplifier (SOA) --- p.2 / Chapter 1.2. --- Applications on optical non-linearity --- p.3 / Chapter 1.2.1. --- Wavelength tunable pulse generation --- p.3 / Chapter 1.2.2. --- Wavelength conversion --- p.5 / Chapter 1.2.3. --- All-optical NRZ to RZ format conversion --- p.7 / Chapter 1.2.4. --- All-optical pulse compression and reshaping --- p.9 / Chapter 1.3. --- Overview --- p.11 / Reference --- p.13 / Chapter 2. --- Principles and Theories --- p.16 / Chapter 2.1. --- Optical non-linearity --- p.17 / Chapter 2.1.1. --- Self-phase modulation (SPM) --- p.19 / Chapter 2.1.2. --- Cross-phase modulation (XPM) --- p.22 / Chapter 2.2. --- Principle of dispersion tuning --- p.25 / Chapter 2.2.1. --- Nonlinear optical loop mirror (NOLM) incorporated with SOA --- p.29 / Chapter 2.2.2. --- Principle of compensated dispersion tuning in harmonically mode-locked fiber ring --- p.33 / Chapter 2.3 --- Principle of double-pass dispersion-shifted fiber (DSF) based on SPM --- p.36 / Reference --- p.38 / Chapter 3. --- Preliminary experimental studies on spectral broadeningin SOAs and DSF by XPM --- p.39 / Chapter 3.1. --- XPM in SOA --- p.40 / Chapter 3.2. --- XPM in DSF --- p.44 / Chapter 3.3. --- Comparison in XPM performance between SOA and DSF --- p.47 / Chapter 4. --- Harmonically mode-locked fiber laser with an optically selectable wavelength --- p.48 / Chapter 4.1. --- Introduction to wavelength tunable pulse generation and basic idea --- p.49 / Chapter 4.2. --- Experimental details --- p.51 / Chapter 4.3. --- Results and discussions --- p.55 / Chapter 4.4. --- Conclusion --- p.61 / Reference --- p.62 / Chapter 5. --- Spectral broadening by XPM in DSF for wavelength conversion --- p.64 / Chapter 5.1. --- Overview of wavelength conversion --- p.65 / Chapter 5.2. --- Description of experimental setup --- p.67 / Chapter 5.3. --- Optical spectral analysis and eye patterns --- p.69 / Chapter 5.4. --- Data Analysis --- p.72 / Chapter 5.5. --- Conclusion --- p.75 / Reference --- p.76 / Chapter 6. --- Spectral filtering from a cross-phase modulated signal for all- optical NRZ to RZ format conversion --- p.77 / Chapter 6.1. --- Importance of format conversion --- p.78 / Chapter 6.2. --- Principle and explanation of experimental setup --- p.79 / Chapter 6.3. --- Experimental results and bit error rate test --- p.81 / Chapter 6.4. --- Conclusion --- p.87 / Reference --- p.88 / Chapter 7. --- Spectral filtering from a cross-phase modulated signal for all- optical pulse compression and reshaping in a DSF --- p.90 / Chapter 7.1. --- Pulse compression by XPM / Chapter 7.1.1. --- Introduction --- p.91 / Chapter 7.1.2. --- Details of experimental setup --- p.93 / Chapter 7.1.3. --- Experimental results / Chapter 7.1.3.1. --- Output spectra and eye patterns --- p.95 / Chapter 7.1.3.2. --- Data analysis and discussions --- p.97 / Chapter 7.2. --- Pulse restoration by XPM / Chapter 7.2.1. --- Details of experiment --- p.99 / Chapter 7.2.2. --- Output eye patterns --- p.101 / Chapter 7.3. --- Conclusion for pulse compression and reshaping by XPM --- p.102 / Reference --- p.103 / Chapter 8. --- Spectral filtering from a self-phase modulated signal with double-pass DSF for all-optical pulse compression and reshaping --- p.104 / Chapter 8.1. --- Introduction to pulse compression by SPM and basic idea of double-pass DSF --- p.105 / Chapter 8.2. --- Schematic diagram of experimental setup --- p.107 / Chapter 8.3. --- Experimental Results and discussions / Chapter 8.3.1. --- Results measured by optical spectrum analyzer and oscilloscope --- p.109 / Chapter 8.3.2. --- Data comparison with conventional SPM and bit-error rate test --- p.113 / Chapter 8.4. --- Conclusion --- p.117 / Reference --- p.118 / Chapter 9. --- Conclusion and future works / Chapter 9.1. --- Conclusion --- p.119 / Chapter 9.2. --- Possible future works --- p.122 / Appendix / List of publications --- p.A-l

Zhao Jian. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 61-68). / Abstracts in English and Chinese. / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1. --- Applications Background - wdm Transmission Systems --- p.1 / Chapter 1.1.1. --- Long-haul WDM Transmission Systems --- p.3 / Chapter 1.1.2. --- OTDM/WDM Transmission Systems --- p.4 / Chapter 1.2. --- Spectrum-slicing Multi-wavelength Sources --- p.6 / Chapter 1.3. --- Introduction of Super-continuum Generation --- p.9 / Chapter 1.4. --- Outline of this Thesis --- p.13 / Chapter 2. --- PRINCIPLES OF SUPER-CONTINUUM GENERATION --- p.15 / Chapter 2.1. --- Super-continuum in Anomalous Dispersive Fiber --- p.17 / Chapter 2.2. --- Super-continuum in Dispersion Decreasing Fiber --- p.21 / Chapter 2.3. --- super-continuum in normal dispersive fiber --- p.23 / Chapter 2.4. --- Super-continuum in Dispersion Flattened and Dispersion Decreasing Fiber --- p.25 / Chapter 2.5. --- Conclusions --- p.27 / Chapter 3. --- OPTIMAL ANALYSIS OF SUPER-CONTINUUM SOURCES OPERATING IN NORMAL DISPERSIVE FIBERS --- p.29 / Chapter 3.1. --- Numerical Model --- p.31 / Chapter 3.2. --- Broadened Spectrum Width --- p.33 / Chapter 3.2.1. --- Broadened Spectrum Width without High-order Dispersion and High-order Nonlinearities --- p.33 / Chapter 3.2.2. --- Influence of High-order Dispersion and High-order Nonlinearities --- p.37 / Chapter 3.3. --- Quality of the Pulses Sliced from SC Spectrum --- p.40 / Chapter 3.3.1. --- Principles --- p.40 / Chapter 3.3.2. --- Influence of Some Parameters on the System Performance of SC Sources --- p.49 / Chapter 3.3.2.1. --- Influence of N --- p.49 / Chapter 3.3.2.2. --- Influence of the Slicing Filter Width --- p.52 / Chapter 3.3.2.3. --- Influence of the Input Peak Power --- p.55 / Chapter 3.4. --- Conclusions --- p.57 / Chapter 4. --- SUMMARY AND FUTURE WORK --- p.59 / BIBLIOGRAPHY --- p.61 / APPENDIX-PUBLICATIONS --- p.68

如今，隨著信息爆炸，骨幹網絡和城域網絡的容量需求已成倍增加。因此，如何提高網絡容量正成為學術界和工業界的熱門話題。可變帶寬光網絡技術通過為不同速率的數據傳輸分配剛剛足夠的帶寬來提高網絡容量，而物理層網絡編碼技術（PNC）在沒有復雜的硬件要求下可以增加網絡容量。在這篇論文中，我們首先提出將組播應用於可變帶寬光網絡來提高網絡容量。我們進一步提出將物理層網絡編碼技術應用於時分複用光接入網絡（TDM-PON），從而來提高全光虛擬專用通信（VPN）的網絡容量。 / 可變帶寬光網絡中組播的分析 / 可變帶寬光網絡相比傳統的波分複用光網絡（WDM）可以提高骨幹網絡的頻譜利用率，因為它可以靈活地分配剛剛足夠的帶寬。另一方面，光網絡層上的組播是一種高效的支持點對多點的通信技術。在未來的許多寬帶服務中，點對多點應用服務是必不可少的，通過光組播技術可以節省頻譜帶寬和接發器的數目。為了進一步提高網絡容量，我們建議在可變帶寬光網絡中進行組播。雖然關於可變帶寬光網絡的研究已經有很多了，但據我們所知，關於可變帶寬光網絡的組播尚未被研究。我們通過兩種有效算法來解決可變帶寬光網絡組播的路由和頻譜分配問題。採用相同的路由和波長/頻譜分配算法，我們研究了有靈活帶寬分配產生的好處，通過比較可變帶寬光網絡和傳統波分複用網絡的組播。我們也探討了由非均勻帶寬分配造成的頻譜間隙對提高網絡容量的影響。 / 時分複用光接入網中(TDM-PON)的物理層網絡編碼技術（PNC） / 網絡編碼是一種很有前途的技術，可以提高網絡的容量和健全性。雖然最近有關於在時分複用光接入網中進行網絡編碼的研究，應用於同一個光接入網絡中的光網絡單元（ONU）之間的通信，但在這些研究中的最大的網絡容量提高只有33。此外，在光網路終端（OLT）和光網絡單元中還需要大量的緩衝來存儲VPN數據。在時分複用光接入網中，全光VPN網絡可以重新將VPN數據傳送到相應的ONU，實現ONU之間的直接通信，不需要在OLT進行光-電-光的轉換。在這裡，據我們所知，我們第一次用實驗驗證了一種新方案，將物理層網絡編碼技術應用於TDM-PON，使得全光VPN通信的網絡容量增加了一倍。我們也提出了在光接入網中的遠程節點處使用光環路器，以此減少VPN通信的插入損耗。當兩個ONU之間需要進行雙向通信，可以通過利用PNC來實現全雙工傳輸，相比傳統半雙工的全光VPN方案，網絡容量可以提高100。實驗結果表明，可以實現無差錯全雙工VPN通信，相比半雙工通信功率補償不超過3分貝，而且這方案中ONU間的同步是不需要的。 / Nowadays, with the information explosion, the capacity demand has been exponentially increasing in backbone networks and metro networks. Therefore, it is becoming a hot topic for both academic and industry to improve the network capacity. Elastic technologies are promising to scale up the network capacity due to just-enough bandwidth allocation for different data-rate traffic request, while physical-layer network coding (PNC) can increase the throughput without complex requirement on hardware. In this thesis, we first propose a novel scheme to improve the network capacity by implementing multicast in elastic optical networks. We further present the capacity improvement by integrating PNC in time-division multiplexing passive optical network (TDM-PON) for all-optical virtual private network (VPN) communications. / Analysis of multicast in elastic optical networks / Elastic optical networks can increase the spectrum utilization of backbone networks compared to the traditional wavelength-division multiplexing (WDM) networks due to flexible and just-enough bandwidth allocation. On the other hand, multicast over the optical layer is a bandwidth-efficient communication technique which supports point-to-multipoint applications. As many broadband services in the future can be from one source to several destinations, it is essential to enable optical multicast to save bandwidth as well as transceivers. To further improve the network throughput, we propose to implement multicast in spectrum elastic optical networks. Although many investigations on elastic optical networks have been carried out, to the best of our knowledge, the performance of multicast in elastic optical networks have not yet been studied. We develop two efficient multicast heuristics to solve the multicast routing and spectrum allocation (MC-RSA) problem in elastic optical networks. By adopting the same routing and wavelength/spectrum allocation algorithms, the benefits of elastic optical networks resulting from flexible bandwidth allocation are studied for multicast compared to the traditional WDM networks. We also investigate the impact of spectral gap caused by non-uniform bandwidth allocation on the improvement of network throughput. / Physical-layer network coding (PNC) in TDM-PON / Network coding is a promising technique to improve the network throughput and robustness. Although network coding in TDM-PON has been recently investigated for exchanging information among optical network units (ONUs) in the same PON, the maximum capacity improvement of inter-ONU communications in these schemes is only 33%. In addition, large electrical buffer is required to store the VPN traffic at both optical line terminal (OLT) and ONUs. All-optical VPN in TDM-PON can optically reroute VPN traffic to the destined ONU without optical-electrical-optical conversion at OLT, which enables direct communications among ONUs. Here, to the best of our knowledge, for the first time, we experimentally demonstrate a novel PNC scheme integrated in TDM-PON for all-optical VPN communications to double the network throughput. A unique remote node that uses optical circulators to reduce the insertion loss of VPN communications is also proposed. By transmitting two inter-ONU traffic streams of opposite direction simultaneously using PNC (full-duplex), it can improve the network throughput by 100% compared to the traditional all-optical VPN schemes (half-duplex). Experiments show that error-free full-duplex VPN communications are achieved, and the power penalty is no more than 3 dB. Synchronization of ONUs is not required for the proposed scheme. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wang, Qike. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 43-48). / Abstracts also in Chinese. / Chapter Chapter 1 --- Background --- p.1 / Chapter 1.1 --- Elastic optical networks --- p.1 / Chapter 1.2 --- Multiscast in WDM networks --- p.5 / Chapter 1.3 --- Network coding in passive optical network (PON) --- p.7 / Chapter 1.4 --- All-optical virtual private nework (VPN) in PON --- p.11 / Chapter 1.5 --- Contribution of this thesis --- p.13 / Chapter 1.6 --- Organization of this thesis --- p.15 / Chapter Chapter 2 --- Analysis of multicast in elastic optical networks --- p.16 / Chapter 2.1 --- Introduction --- p.16 / Chapter 2.2 --- Network model and heuristics --- p.18 / Chapter 2.2.1 --- Multicast-capable node architecture --- p.18 / Chapter 2.2.2 --- Multicast goup size (MGS) factor --- p.19 / Chapter 2.2.3 --- Network resource and assumption --- p.19 / Chapter 2.2.4 --- Multicast routing and spectrum allocation (MC-RSA) heuristics --- p.20 / Chapter 2.3 --- Numerical results --- p.22 / Chapter 2.4 --- Summary --- p.27 / Chapter Chapter 3 --- Physical-layer network coding (PNC) in TDM-PON --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- A novel PNC in TDM-PON scheme for all-optical VPN applications --- p.31 / Chapter 3.2.1 --- System architecture --- p.31 / Chapter 3.2.2 --- Implementation of PNC --- p.32 / Chapter 3.2.3 --- Management of wavelength collision --- p.33 / Chapter 3.3 --- Experiemnts and results --- p.35 / Chapter 3.4 --- Summary --- p.39 / Chapter Chapter 4 --- Conclusion and Future Works --- p.40 / Chapter 4.1 --- Conclusion of this thesis --- p.40 / Chapter 4.2 --- Future works --- p.41 / Bibliography --- p.43 / List of Publications --- p.50

Li, Pulan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 60-66). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview of wavelength division multiplexed passive optical network (WDM-PON) and colorless optical network unit (ONU) --- p.1 / Chapter 1.2 --- Implementation of colorless ONU --- p.4 / Chapter 1.3 --- Rayleigh backscattering in WDM-PON --- p.6 / Chapter 1.4 --- Motivation of this thesis --- p.9 / Chapter 1.5 --- Outline of this thesis --- p.11 / Chapter Chapter 2 --- Previous works of remodulation for WDM-PON --- p.12 / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Devices utilized by colorless ONU in remodulation schemes --- p.13 / Chapter 2.2.1 --- Injection-locked Fabry-Perot laser diode at ONU --- p.13 / Chapter 2.2.2 --- Reflective semiconductor optical amplifier --- p.15 / Chapter 2.2.3 --- Reflective electro-absorption modulator and semiconductor optical amplifier (REAM-SOA) --- p.17 / Chapter 2.3 --- Modulation methods in remodulation schemes --- p.18 / Chapter 2.4 --- Summary --- p.23 / Chapter Chapter 3 --- A remodulation scheme based on time-interleaved DPSK modulation format --- p.25 / Chapter 3.1 --- Introduction --- p.25 / Chapter 3.2 --- Operation principle: time-interleaving technology for phase-modulated signal --- p.27 / Chapter 3.3 --- System architecture --- p.28 / Chapter 3.4 --- Experimental results and discussion --- p.31 / Chapter 3.5 --- Effect of timing misalignment on proposed remodulation scheme --- p.33 / Chapter 3.6 --- Summary --- p.35 / Chapter Chapter 4 --- Enhanced Tolerance to Rayleigh Backscattering in Remodulation Scheme Using Time-Interleaved DPSK Format --- p.37 / Chapter 4.1 --- Introduction --- p.37 / Chapter 4.2 --- Studies on Rayleigh backscattering suppression in optical domain --- p.39 / Chapter 4.2.1 --- RB suppression in carrier-distributed schemes --- p.39 / Chapter 4.2.2 --- RB suppression in remodulation schemes --- p.40 / Chapter 4.2 --- Experimental setup and results --- p.42 / Chapter 4.3 --- Discussion on RB suppression effect of the proposed scheme --- p.46 / Chapter 4.3.1 --- Theoretical study and simulation results --- p.46 / Chapter 4.3.2 --- Experimental demonstration of spectral relationship between signals and RB crosstalk --- p.49 / Chapter 4.4 --- Summary --- p.53 / Chapter Chapter 5 --- Conclusion and Future Works --- p.55 / Chapter 5.1 --- Conclusion of this thesis --- p.55 / Chapter 5.2 --- Future works --- p.57 / List of Publications --- p.59 / Bibliography --- p.60

Active mode locking is one of the simplest ways to generate picosecond pulses at gigahertz repetition rates. In my works, I demonstrate the generation of picosecond pulses with a center-wavelength spanning from 1489nm to 1589nm using a polarization maintaining fiber loop mirror filter (PMF-LMF) in a mode-locked semiconductor optical amplifier (SOA) ring laser. By applying the SOA gain shifting technique and with the help of the controllable transmission ratio of the PMF-LMF, the tuning range of the output wavelength can be extended. By applying the technique of dispersion tuning, electrical wavelength tuning can be achieved across a range of 100nm. / Compared to the active mode-locking method, the regenerative mode-locking is very convenient because it does not require any external source for modulation and is proved to be more robust against fluctuations in ambient temperature. We demonstrate a 10-GHz regeneratively mode-locked fiber laser using a PMF-LMF. The operating frequency is determined by the free-spectral-range of the PMF-LMF and the component is extracted optically from the ring laser output. / In addition, we also demonstrate a simple technique to generate wavelength tunable picosecond pulses at adjustable repetition rate without using electrical or optical RF filter to extract the radio frequency (RF). The RF signal for mode locking is generated from a Fabry-Perot laser diode (FP-LD) under optical injection. The output frequency can be varied by adjusting the biasing current of the FP-LD. (Abstract shortened by UMI.) / Picosecond optical pulse sources with broad tunability and various repetition rates are key elements for applications in wavelength- and time-division multiplexed optical transmission systems. Mode-locking is one of the main techniques for the generation of optical pulses with high repetition rate picosecond pulse trains. This thesis presents our research efforts in high repetition rate optical pulse generation using active and regenerative mode-locking techniques, and a self-starting approach. We also demonstrate the application of harmonic mode locking in all-optical clock recovery from NRZ data. / Tang Wing Wa. / "August 2005." / Adviser: C. T. Shu. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 4015. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

OFS provisions bandwidth in the granularity of one wavelength. With such a coarse granularity, most applications including video download, HDTV, 3D movie, and 3D TV etc. will have very short flow sizes, in the order of seconds or even sub-second, which brings challenges to the utilization efficiency of bandwidth capacity. In this thesis we study the performance of OFS for short flows. The constraint of network resources is investigated. The effect of destination and path blocking is studied. A distributed scheduling protocol called Multi-Destination Control Protocol (MDCP) is proposed to deal with such constraint. Both single wavelength and multi-wavelength configurations are studied and characterized. Simulation results demonstrate that MDCPcan improve the OFS network throughput significantly and can be as much as eighty to one hundred percent for a single-wavelength OFS network. Even for an OFS network with four wavelengths, the throughput improvement can still approach 40%. / The Internet traffic has been growing tremendously. China Telecom predicts that the compound annual growth rate of IP traffic for the next decade is at 56% - 80% and the backbone capacity will grow by another two orders of magnitudes. Furthermore, the power consumption incurred by the next generation of huge electronic IP packet switching routers in the backbone will exceed gigawatts. In view of the grave enviromnental concerns, there is a great need for a more efficient way of transporting and switching the bits. This thesis investigates a new all-optical networking technology called optical flow switching (OFS). OFS bypasses electronic routers, and provides end-to-end transparent connections, thus taking full advantage of the enormous transmission capacity of optical networks and enjoying the extremely low error rate of transparent data transmission. The most important point about OFS is that it reduces the electrical power consumption by off-loading the huge electronic routers, which could be a major constraint for future Internet growth. Unlike many other exotic all-optical switching technologies, OFS is immediately deployable using the current optical technologies, Therefore OFS is very attractive for the next generation optical networks. / Qian, Zhengfeng. / Adviser: Kwok-wai Cheung. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 113-118). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.