Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Periodic structures with a sub-wavelength pitch have been known since Hertz conducted his first experiments on the polarization of electromagnetic waves. While the use of these structures in waveguide optics was proposed in the 1990s, it has been with the more recent developments of silicon photonics and high-precision lithography techniques that sub-wavelength structures have found widespread application in the field of pho- tonics. This review first provides an introduction to the physics of sub-wavelength structures. An overview of the applications of sub-wavelength structures is then given including: anti-reflective coatings, polarization rotators, high-efficiency fiber-chip cou- plers, spectrometers, high-reflectivity mirrors, athermal waveg- uides, multimode interference couplers, and dispersion engi- neered, ultra-broadband waveguide couplers among others. Particular attention is paid to providing insight into the design strategies for these devices. The concluding remarks provide an outlook on the future development of sub-wavelength structures and their impact in photonics.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/lpor.201400083

Waveguide sub-wavelength structures: a review of principles and applications

Part I. Silicon Photonics - Introduction: 1. Fabless Silicon Photonics: 1.1 Introduction 1.2 Silicon photonics - the next fabless semiconductor industry 1.3 Applications 1.4 Technical challenges and the state of the art 1.5 Opportunities 2. Modelling and Design Approaches: 2.1 Optical Waveguide Mode Solver 2.2 Wave Propagation 2.3 Optoelectronic models 2.4 Microwave Modelling 2.5 Thermal Modelling 2.6 Photonic Circuit Modelling 2.7 Physical Layout 2.8 Software Tools Integration Part II. Silicon Photonics - Passive Components: 3. Optical Materials and Waveguides: 3.1 Silicon-on-Insulator 3.2 Waveguides 3.3 Bent waveguides 3.4 Code Listings 3.5 Problems 4. Fundamental Building Blocks: 4.1 Directional couplers 4.2 Y-Branch 4.3 Mach-Zehnder Interferometer 4.4 Ring resonators 4.5 Waveguide Bragg Grating Filters 4.6 Code Listings 4.7 Problems 5. Optical I/O: 5.1 The challenge of optical coupling to silicon photonic chips 5.2 Grating Coupler 5.3 Edge Coupler 5.4 Polarization 5.5 Code Listings 5.6 Problems Part III. Silicon Photonics - Active Components: 6. Modulators: 6.1 Plasma Dispersion E 6.2 PN Junction Phase Shifter 6.3 Micro-ring Modulators 6.4 Forward-biased PIN Junction 6.5 Active Tuning 6.6 Thermo-Optic Switch 6.7 Code Listings 6.8 Problems 7. Detectors: 7.1 Performance Parameters 7.2 Fabrication 7.3 Types of detectors 7.4 Design Considerations 7.5 Detector modelling 7.5.2 Electronic Simulations 7.6 Code Listings 7.7 Problems 8. Lasers: 8.1 External Lasers 8.2 Laser Modelling 8.3 Co-Packaging 8.4 Hybrid Silicon Lasers 8.5 Monolithic Lasers 8.6 Alternative Light Sources 8.7 Problems Part IV. Silicon Photonics - System Design: 9. Photonic Circuit Modelling: 9.1 Need for photonic circuit modelling 9.2 Components for System Design 9.3 Compact Models 9.4 Directional Coupler - Compact Model 9.5 Ring Modulator - Circuit Model 9.6 Grating Coupler - S Parameters 9.7 Code Listings 10. Tools and Techniques: 10.1 Process Design Kit (PDK) 10.2 Mask Layout 11. Fabrication: 11.1 Fabrication Non-Uniformity 11.2 Problems 12. Testing and Packaging: 12.1 Electrical and Optical Interfacing 12.2 Automated Optical Probe Stations 12.3 Design for Test 13. Silicon Photonic System Example: 13.1 Wavelength Division Multiplexed Transmitter.

Silicon Photonics Design: From Devices to Systems

Over the last 20 years, silicon photonics has revolutionized the field of integrated optics, providing a novel and powerful platform to build mass-producible optical circuits. One of the most attractive aspects of silicon photonics is its ability to provide extremely small optical components, whose typical dimensions are an order of magnitude smaller than those of optical fiber devices. This dimension difference makes the design of fiber-to-chip interfaces challenging and, over the years, has stimulated considerable technical and research efforts in the field. Fiber-to-silicon photonic chip interfaces can be broadly divided into two principle categories: in-plane and out-of-plane couplers. Devices falling into the first category typically offer relatively high coupling efficiency, broad coupling bandwidth (in wavelength), and low polarization dependence but require relatively complex fabrication and assembly procedures that are not directly compatible with wafer-scale testing. Conversely, out-of-plane coupling devices offer lower efficiency, narrower bandwidth, and are usually polarization dependent. However, they are often more compatible with high-volume fabrication and packaging processes and allow for on-wafer access to any part of the optical circuit. In this paper, we review the current state-of-the-art of optical couplers for photonic integrated circuits, aiming to give to the reader a comprehensive and broad view of the field, identifying advantages and disadvantages of each solution. As fiber-to-chip couplers are inherently related to packaging technologies and the co-design of optical packages has become essential, we also review the main solutions currently used to package and assemble optical fibers with silicon-photonic integrated circuits.

/pdf/coupling-strategies-for-silicon-photonics-integrated-chips-2mkn7m5fwz.pdf

Coupling strategies for silicon photonics integrated chips [Invited]

Silicon photonics has experienced phenomenal transformations over the last decade. In this paper, we present some of the notable advances in silicon-based passive and active optical interconnect components, and highlight some of our key contributions. Light is also cast on few other parallel technologies that are working in tandem with silicon-based structures, and providing unique functions not achievable with any single system acting alone. With an increasing utilization of CMOS foundries for silicon photonics fabrication, a viable path for realizing extremely low-cost integrated optoelectronics has been paved. These advances are expected to benefit several application domains in the years to come, including communication networks, sensing, and nonlinear systems.

Recent advances in silicon-based passive and active optical interconnects

We present a rigorous approach for designing a highly efficient coupling between single mode optical fibers and silicon nanophotonic waveguides based on diffractive gratings. The structures are fabricated on standard SOI wafers in a cost-effective CMOS process flow. The measured coupling efficiency reaches −1.08 dB and a record value of −0.62 dB in the 1550 nm telecommunication window using a uniform and a nonuniform grating, respectively, with a 1dB-bandwidth larger than 40 nm.

Bridging the gap between optical fibers and silicon photonic integrated circuits.

We present a highly efficient 1-D grating structure that serves to couple light between standard optical fibers and single-mode waveguides in the silicon-on-insulator platform and to split both orthogonal polarization states. The efficiency of the fabricated coupler is enhanced by a backside metal mirror and reaches -2.4 dB for both polarizations at 1552 nm with an extinction ratio >25 dB in a wide wavelength range. The efficiency can be theoretically improved to -1.1 dB when optimizing the number of periods and using a nonuniform grating.

CMOS-Compatible Polarization Splitting Grating Couplers With a Backside Metal Mirror

We report a highly efficient grating coupler fabricated using a CMOS-compatible technology process with a record efficiency of -0.64 dB (86.3 %) at a wavelength of 1527 nm and a 1dB-bandwidth of 44 nm. The performance of the structure is enhanced through a backside metal mirror and the use of a nonuniform grating.

Andreas Kunze

Papers

Bridging the gap between optical fibers and silicon photonic integrated circuits.

CMOS-Compatible Polarization Splitting Grating Couplers With a Backside Metal Mirror

CMOS-compatible nonuniform grating coupler with 86% coupling efficiency