Eight-input optical programmable logic array enabled by parallel spectrum modulation

Despite over 40 years' development of optical logic computing, the studies have been still struggling to support more than four operands, since the high parallelism of light has not been fully leveraged blocked by the optical nonlinearity and redundant input modulation in existing methods. Here, we propose a scalable multi-input optical programmable logic array (PLA) with minimal logical input, enabled by parallel spectrum modulation. By making full use of the wavelength resource, an eight-input PLA is experimentally demonstrated, and there are 2^256 possible combinations of generated logic gates. Various complex logic fuctions, such as 8-256 decoder, 4-bit comparator, adder and multiplier are experimentally demonstrated via leveraging the PLA. The scale of PLA can be further extended by fully using the dimensions of wavelength and space. As an example, a nine-input PLA is implemented to realize the two-dimensional optical cellular automaton for the first time and perform Conway's Game of Life to simulate the evolutionary process of cells. Our work significantly alleviates the challenge of extensibility of optical logic devices, opening up new avenues for future large-scale, high-speed and energy-efficient optical digital computing

Design of Ultrafast All-Optical Pseudo Binary Random Sequence Generator, 4-bit Multiplier and Divider using 2 x 2 Silicon Micro-ring Resonators

All-optical devices are essential for next generation ultrafast, ultralow-power and ultrahigh bandwidth information processing systems. Silicon microring resonators (SiMRR) provide a versatile platform for all-optical switching and CMOS-compatible computing, with added advantages of high Q-factor, tunability, compactness, cascadability and scalability. A detailed theoretical analysis of ultrafast all-optical switching 2 x 2 SiMRRs has been carried out incorporating the effects of two photon absorption induced free-carrier injection and thermo optic effect. The results have been used to design simple and compact all-optical 3-bit and 4-bit pseudo-random binary sequence generators and the first reported designs of all-optical 4 x 4-bit multiplier and divider. The designs have been optimized for low-power, ultrafast operation with high modulation depth, enabling logic operations at 45 Gbps.Comment: 13 pages, 4 figures. Submitted at Journal (Optik) for publicatio

Adiabatic technique based low power synchronous counter design

The performance of integrated circuits is evaluated by their design architecture, which ensures high reliability and optimizes energy. The majority of the system-level architectures consist of sequential circuits. Counters are fundamental blocks in numerous very large-scale integration (VLSI) applications. The T-flip-flop is an important block in synchronous counters, and its high-power consumption impacts the overall effectiveness of the system. This paper calculates the power dissipation (PD), power delay product (PDP), and latency of the presented T flip-flop. To create a 2-bit synchronous counter based on the novel T flip-flops, a performance matrix such as PD, latency, and PDP is analyzed. The analysis is carried out at 100 and 10 MHz frequencies with varying temperatures and operating voltages. It is observed that the presented counter design has a lesser power requirement and PDP compared to the existing counter architectures. The proposed T-flip-flop design at the 45 nm technology node shows an improvement of 30%, 76%, and 85% in latency, PD, and PDP respectively to the 180 nm node at 10 MHz frequency. Similarly, the proposed counter at the 45 nm technology node shows 96% and 97% improvement in power dissipation, delay, and PDP respectively compared to the 180 nm at 10 MHz frequency

Doctor of Philosophy

dissertationRecent breakthroughs in silicon photonics technology are enabling the integration of optical devices into silicon-based semiconductor processes. Photonics technology enables high-speed, high-bandwidth, and high-fidelity communications on the chip-scale-an important development in an increasingly communications-oriented semiconductor world. Significant developments in silicon photonic manufacturing and integration are also enabling investigations into applications beyond that of traditional telecom: sensing, filtering, signal processing, quantum technology-and even optical computing. In effect, we are now seeing a convergence of communications and computation, where the traditional roles of optics and microelectronics are becoming blurred. As the applications for opto-electronic integrated circuits (OEICs) are developed, and manufacturing capabilities expand, design support is necessary to fully exploit the potential of this optics technology. Such design support for moving beyond custom-design to automated synthesis and optimization is not well developed. Scalability requires abstractions, which in turn enables and requires the use of optimization algorithms and design methodology flows. Design automation represents an opportunity to take OEIC design to a larger scale, facilitating design-space exploration, and laying the foundation for current and future optical applications-thus fully realizing the potential of this technology. This dissertation proposes design automation for integrated optic system design. Using a buildingblock model for optical devices, we provide an EDA-inspired design flow and methodologies for optical design automation. Underlying these flows and methodologies are new supporting techniques in behavioral and physical synthesis, as well as device-resynthesis techniques for thermal-aware system integration. We also provide modeling for optical devices and determine optimization and constraint parameters that guide the automation techniques. Our techniques and methodologies are then applied to the design and optimization of optical circuits and devices. Experimental results are analyzed to evaluate their efficacy. We conclude with discussions on the contributions and limitations of the approaches in the context of optical design automation, and describe the tremendous opportunities for future research in design automation for integrated optics

Optical Communication

Optical communication is very much useful in telecommunication systems, data processing and networking. It consists of a transmitter that encodes a message into an optical signal, a channel that carries the signal to its desired destination, and a receiver that reproduces the message from the received optical signal. It presents up to date results on communication systems, along with the explanations of their relevance, from leading researchers in this field. The chapters cover general concepts of optical communication, components, systems, networks, signal processing and MIMO systems. In recent years, optical components and other enhanced signal processing functions are also considered in depth for optical communications systems. The researcher has also concentrated on optical devices, networking, signal processing, and MIMO systems and other enhanced functions for optical communication. This book is targeted at research, development and design engineers from the teams in manufacturing industry, academia and telecommunication industries

복소, 무질서 및 광학적 비선형 퍼텐셜에서의 대칭성 붕괴를 통한 빛의 흐름 제어

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 박남규.매질 내 빛의 흐름은 통상적으로 거시적 맥스웰 방정식에 의해 정의된다. 동질성 및 등방성을 가지고, 선형적이며, 시간에 대해 일정한 광학 매질 변수를 갖는 이상적인 매질에서는 광파의 양상이 페르마의 원리의 직접적인 예인 진동하는 전자기장의 직진 형태로, 간단하며 직관적이다. 이러한 평면파적 특성은 기하 광학의 바탕이며, 슈뢰딩거 방정식 형태의 파동 방정식이 갖는 다양한 대칭성 (병진 대칭, 키랄 대칭, 에르미트 대칭, 로렌츠 대칭 및 시간 반전 대칭)의 보존에서 그 원리을 찾을 수 있다. 렌즈, 거울 및 프리즘과 같은 고전적인 방식에서조차, 빛의 흐름을 조절키 위해서는 일부 광학적 대칭성의 붕괴를 필요로 한다. 비균질 매질에서의 병진 대칭의 붕괴는 굴절, 반사, 회절과 같은 산란 기반 빛 제어를 위한 고전적인 방법이다. 전파 시의 빛 에너지의 소모 또는 증폭은 파동 방정식의 비에르미트 헤밀토니안에 의해 정량화된다. 키랄 분자로 이루어진 매질은 광학 활성, 즉 빛의 편광을 돌릴 수 있도록 한다. 천문학에서 별 및 은하 움직임의 관찰에 이용되는 광학적 도플러 효과는 로렌츠 대칭성을 붕괴시키는 광원의 시간에 따른 변화에 기반한다. 비직관적인 이론적 결과물 및 향상된 공정 기술을 포함하는 광학 분야의 최근 성과들은 이제 비고전적인 빛의 흐름을 이끌어내기 위한 광학적 퍼텐셜 제어의 새로운 영역을 개척하고 있다. 메타 물질 개념과 연계된 나노 스케일 기술은 단방향 빛 전파, 변형된 스넬의 법칙, 음굴절율, 투명 망토, 완전 흡수체와 같은 특이한 빛의 흐름을 지원하는, 이론적으로 증명된 인조 매질의 설계를 가능케 한다. 광 증폭 기술의 발전은 양자역학적 개념인 패리티-시간 대칭성의 구현에 적용되어, 복소 퍼텐셜에서의 새로운 종류의 광학을 탄생시켰다. 이러한 성취물들은 맥스웰 방정식에서의 더 넓고 급격한 형태의 대칭성 붕괴에 기반하기 때문에, 의도된 빛의 흐름 조절을 위해서는 다양한 대칭성 붕괴에 관한 심도있는 연구가 필요하다. 본 학위 논문에서는 복소, 불규칙, 비선형 광학 퍼텐셜과 같은 다양한 플랫폼에서의 대칭성 붕괴에 대하여 살펴보고자 한다. 본 연구는 패리티-시간 대칭성, 키랄 특성, 인과율, 초대칭, 생물 모방 기술, 모드 경계 광학 및 느린 빛 원리와 연계된 빛의 특이한 흐름에 집중한다. 본 연구진이 이끌어낸 비직관적인 개념 및 광소자의 새로운 설계 기법 관련 결과들은 비고전적인 빛의 흐름에 기반한 미래 광학 발전에 도움이 될 것이다.The flow of light in matters is usually defined by macroscopic Maxwells equations. In ideal media with homogeneous, isotropic, linear, and time-invariant optical material parameters, the aspect of light wave dynamics is simple and intuitive: propagating straight with oscillated electromagnetic fields, as the direct example of Fermats principle. This planewave dynamics, the basis of geometric optics, originates from the conservation of various symmetries of the Schrodinger-like wave equation, including translational and chiral symmetry, Hermitian symmetry, Lorentz reciprocity, and time-reversal symmetry. To control the flow of light even in a classical manner such as lens, mirror, and prism, some parts of the symmetries in optics should be broken. Breaking the translational symmetry with inhomogeneous materials is the traditional method of controlling light by scattering such as refraction, reflection, and diffraction. The dissipation or amplification of optical energy during the propagation is quantified by the non-Hermitian Hamiltonian of the wave equation. The materials composed of chiral molecules allow the rotation of the polarization of light, i.e. optical activity. The optical Doppler effect, which has been employed in astronomy for the observation of the motion of stars and galaxies, is based on the time-varying position of light sources, breaking Lorentz reciprocity. Recent achievements in optics, including counterintuitive theoretical results and improved fabrication technologies, have now been pioneering unprecedented regimes of controlling optical potentials which derive non-classical flow of light. Nano-scale technologies linked with the concept of metamaterials have opened a path to the design of theoretically-demonstrated artificial media supporting extraordinary light flows: such as unidirectional light flow, modified Snells law, negative index, cloaking, and perfect absorption. The development of optical amplification techniques has been applied to the realization of the quantum-mechanical notion of parity-time symmetry: stimulating a new class of optics in complex potentials. Because these achievements have been based on broader and drastic forms of symmetry breaking in Maxwells equations, in-depth investigation of various symmetry breakings is now imperative to realize designer manipulation of light flow. In this dissertation, we explore symmetry breakings in various platforms: complex, disordered, and nonlinear optical potentials. The investigation is focused on unconventional flows of light linked with the notions of parity-time symmetry, chirality, causality, supersymmetry, biomimetics, mode junction photonics, and slow-light. We believe that our results including counterintuitive concepts and novel design methods for optical devices will be the foundation of future development in optics based on non-classical flow of light.Table of Contents Abstract i Table of Contents iv List of Figures viii Chapter 1 Introduction １ 1.1 Why should we break the symmetry of light? １ 1.2 Outline of the dissertation ２ Chapter 2 Parity-Time Symmetric Optics ４ 2.1 Introduction to PT-symmetric optics ５ 2.2 PT-symmetric waves in the spatial domain １１ 2.2.1 2-level chirped system １１ 2.2.2 N-level photonic molecule ２４ 2.3 PT-symmetric waves in momentum domains ４３ 2.3.1 Optical chirality in low-dimensional eigensystems ４４ 2.3.2 Interpretation of PT-symmetry in k-space ６３ 2.4 Conclusion ７５ Chapter 3 Disordered Optics ７６ 3.1 Introduction to disordered optics ７７ 3.2 Supersymmetric bandgap in disorder ７８ 3.2.1 Wave dynamics in random-walk potentials ７９ 3.2.2 Supersymmetric transformation for isospectrality ８３ 3.2.3 Bloch-wave family with tunable disorder ８６ 3.3 Biomimetic disordered surface ９１ 3.4 Conclusion ９８ Chapter 4 All-Optical Devices with Nonlinearity ９９ 4.1 Introduction to all-optical devices １００ 4.2 Mode junction photonics １０１ 4.2.1 Photonic Junction Diode １０５ 4.2.2 Multi-Junction Half Adder １１３ 4.3 Slow-light enhanced optical functionalities １１５ 4.3.1 Multiband slow light １１６ 4.3.2 Optical A/D converter １２６ 4.3.3 All-optical A/D converter １３７ 4.3.4 Travelling-wave all-optical isolator １４３ 4.4 Conclusion １４９ Chapter 5 Conclusion １５０ Appendix A Eigenvalues in PT-Meta-molecules １５２ Appendix B Supplements for Section 2.3.1 １５７ B.1 Planewave solution of a PT-symmetric optical material １５７ B.2 Density of optical chirality for complex eigenmodes １５８ B.3 Effect of imperfect PT symmetry on the modal chirality １５９ B.3.1 Broken symmetry in the real part of permittivity １５９ B.3.2 Broken anti-symmetry in the imaginary part of the permittivity １６１ B.4 Transfer between RCP and LCP modes in the PT-symmetric chiral material １６２ B.4.1 Propagation of complex eigenmodes １６２ B.4.2 Strength of chiral conversion CCS before the EP １６３ B.5 The state of polarization (SOP) at the EP: Optical spin black hole １６４ B.6 Giant chiral conversion in the resonant structure １６５ B.7 Detailed information of fabrication and experiment in THz chiral polar metamaterials １６６ B.7.1 Fabrication process of THz chiral polar metamaterials １６６ B.7.2 THz-TDS system for the measurement of intermodal chirality １６７ B.8 Realization of PT-symmetric permittivity in metamaterial platforms １６７ B.9 Design parameters of chiral waveguides １７１ B.10 Low-dimensional linear polarization １７１ Appendix C Detailed Derivation for Section 2.3.2 １７３ C.1 Detailed derivation of Eq. (2.20) １７３ C.2 Serial calculation of discretized coupled mode equations １７５ Appendix D Analytical Methods for Section 3.2 １７７ D.1 Details of the FDM and FGH method １７７ D.2 Calculation of the Hurst exponent １７７ Appendix E Supplements for Section 4.2 １７９ E.1 Details of the device structures and numerical method used in the study １７９ E.2 Coupled mode theory for the di-atomic photonic junction diode １８１ E.2.1 Analytical model and coupled mode equations １８１ E.2.2. Solution of resonator field (a1, a2, a3) １８３ E.2.3 Implementation of Kerr nonlinearity and calculation of diode throughput １８５ Bibliography １８７ Abstract in Korean ２０３Docto

Cumulative index to NASA Tech Briefs, 1970-1975

Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented