Silicon Photonics IV: Innovative Frontiers (Topics in Applied Physics, 139)

Preface
Contents
Contributors
Part I Advances in Fundamental Research
1 Optical Properties of Si Nanocrystals Enhanced by Ligands
	1.1  Introduction
		1.1.1 Quantum Confinement
		1.1.2 Complex Role of Surface Chemistry
		1.1.3 The K K K K-Space Projections of the Density of States
	1.2 Fast Radiative Rate in Hydrogen- and Oxide-Capped Silicon Nanocrystals
		1.2.1 Oxidation of Hydrogen-Terminated Silicon Nanocrystals
		1.2.2 Emergence of the F-Band in Oxidized Si-NC
		1.2.3 Silica Defects
		1.2.4 Role of Nitrogen
	1.3 Organically Coated Si-NCs with a Fast Emission Rate
		1.3.1 Single-Dot Spectroscopy of Si-NCs with Fast Radiative Rates
		1.3.2 Enhanced Radiative Rate Measured by Drexhage Experiment
	1.4 Theoretical Simulations of Si-NCs with Ligands
		1.4.1 Role of an Electronegative Ligand/Environment
		1.4.2 Role of Tensile Strain
		1.4.3 Interplay Between the Charge Transfer and Tensile Strain
		1.4.4 Thermal Population of States
	1.5 Summary and Outlooks
	References
2 Light-Emission from Ion-Implanted Group-IV Nanostructures
	2.1 Introduction to the Chapter
		2.1.1 Background
		2.1.2 In a Nutshell: Potential Light Sources for Si Photonics
		2.1.3 All-Group-IV Approaches
		2.1.4 Group-III-V on Group-IV Approaches
	2.2 Epitaxial Group-IV Nanostructures on Silicon
	2.3 Ion Implantation into Ge Quantum Dots on Silicon
		2.3.1 DEQD Fabrication Procedure
		2.3.2 Light-Emission from DEQDs
		2.3.3 Considerations Toward Large-Scale Integration Possibilities
		2.3.4 Electrical Injection
		2.3.5 Scalability of DEQD Densities
		2.3.6 Thermal Budget and Annealing of DEQDs
		2.3.7 Curing and Passivation of Non-radiative Recombination Centers
	2.4 Summary and Future Directions in DEQD Research
	References
3 Lasing in Group-IV Materials
	3.1 Introduction
	3.2 Fabrication: Ge-Based Epitaxy and Processes for Group-IV Indirect and Direct Bandgap Material
		3.2.1 Germanium Growth
		3.2.2 Germanium Tin Growth
		3.2.3 Ge-Based Materials Processing
		3.2.4 Electrical Contacts on Ge-Based Materials: A Focus on GeSn
	3.3 Effects of Strain and Sn for Bandstructure Manipulation
		3.3.1 Strain Control in Germanium-Based Materials
		3.3.2 Band Structures and Band Alignment
		3.3.3 Gain Calculation of Strained Ge-Based Materials (Ge, GeSn, SiGeSn)
	3.4 Group-IV Lasing
		3.4.1 Optical Cavity Design
		3.4.2 Lasing in Ge
		3.4.3 Lasing in GeSn
	3.5 Optoelectronic Devices
		3.5.1 Photodetectors
		3.5.2 Electrically Pumped Devices
	3.6 Outlook and Conclusion
	References
4 Light Emission from Germanium Nanostructures
	4.1 Introduction
	4.2 Optical Properties of Bulk Ge
		4.2.1 Band Structure
		4.2.2 Absorption
		4.2.3 Temperature Dependence—Ge Energy Gap
		4.2.4 Stress
		4.2.5 Optical Emission from Bulk Ge
	4.3 Developments with Ge for Photonic Emitters
	4.4 Optical Emission from Ge Nanocrystals
		4.4.1 Outline
		4.4.2 Photoluminescence (PL) Measurements
		4.4.3 Ge Quantum Dot Ensembles
		4.4.4 Self-organized Ge Nanocrystals (NCs)
	4.5 Prospects for CMOS Compatible Devices
	References
5 Optical Spin Orientation in Ge-Based Heterostructures
	5.1 Introduction
		5.1.1 A Minimal Guide to Optical Spin Orientation
	5.2 Bulk Ge
		5.2.1 Energy Relaxation and Spin Dynamics
		5.2.2 Spin Lifetime
	5.3 Ge Heterostructures
		5.3.1 Strained Ge Epilayer
		5.3.2 Quantum Confined Heterostructures: Ge/SiGe Quantum Wells
	5.4 Alloying Ge with Sn
		5.4.1 Spin Relaxation and Spin Dephasing Time in GeSn
	5.5 Future Perspective
		5.5.1 Spin Photodiode and Spin-LEDs
		5.5.2 Spin-Charge Interconversion Phenomena
	5.6 Conclusion
	References
Part II Advances in Integration Architectures
6 Subwavelength Silicon Photonics
	6.1 Introduction
	6.2 Effective Medium Theory
		6.2.1 Rytovs’s Equations and Application in Periodic Dielectric Subwavelength Gratings
		6.2.2 Spectral Range of Validity of EMT
	6.3 Subwavelength Waveguide Grating Couplers
		6.3.1 Introduction
		6.3.2 A Brief Review
		6.3.3 Uniform Subwavelength Grating Couplers
		6.3.4 Apodized Subwavelength Grating Couplers
		6.3.5 Polarization-Independent Grating Couplers
		6.3.6 Wideband Grating Couplers
		6.3.7 Focusing Apodized Subwavelength Grating Coupler
		6.3.8 Broadband Focusing Subwavelength Grating Coupler
		6.3.9 Polarization-Insensitive Focusing Subwavelength Grating Coupler
	6.4 Use of SWGs for Waveguide Devices and Mid-IR Photonics
	6.5 Numerical Optimization for the Design of Subwavelength Structures
		6.5.1 Perfectly Vertical Grating Coupler for Multi-core Fiber
		6.5.2 Subwavelength Dual-Polarization Grating Coupler for Few-Mode Fiber
		6.5.3 Dual-Wavelength-Band Focusing Subwavelength Grating Couplers (DWB FSWGCs)
		6.5.4 Hyperuniform Disordered Silicon Photonic (HUDSiP) Polarizers
	6.6 Conclusion
	References
7 Non-Hermitian Physics and Engineering in Silicon Photonics
	7.1 Introduction
	7.2 Non-Hermitian Physics: From Quantum Mechanics to Optics
		7.2.1 Non-Hermitian Physics in Quantum Mechanics
		7.2.2 Paraxial Propagation of Electromagnetic Fields in a Transverse Complex Potential
		7.2.3 Wave Scattering in a Longitudinal Complex Potential
		7.2.4 Non-Hermitian Optical Waveguides and Resonators
	7.3 Spectral Singularity and Enhanced Sensing
		7.3.1 Spectral Singularity at Exceptional Points
		7.3.2 EP-Enhanced Nanoparticle Sensor
		7.3.3 EP-Enhanced Gyroscope
	7.4 Mode Interactions and Lasing Effects
		7.4.1 Chiral Modes at Exceptional Points
		7.4.2 Unidirectional Lasing
		7.4.3 Single-Mode Lasers
		7.4.4 Revival of Lasing by Loss
		7.4.5 Petermann Factor and Laser Linewidth
		7.4.6 Other Non-Hermitian Lasing Behavior
	7.5 Scattering Properties and Light Propagation
		7.5.1 Unidirectional Zero Reflection at Exceptional Points
		7.5.2 Nonreciprocal Light Transport in Nonlinear Parity-Time Symmetric Systems
		7.5.3 Electromagnetically Induced Transparency in Non-Hermitian Systems
	7.6 Topological Features and Mode Switching
		7.6.1 Dynamics of Encircling EPs
		7.6.2 Asymmetric Mode Switching
	7.7 Conclusion and Outlook
	References
8 Topological Photonics with Microring Lattices
	8.1 Introduction
	8.2 Topological Photonic Insulators in 1D Microring Lattices
		8.2.1 1D Microring Lattice as an SSH Topological Insulator
		8.2.2 1D Microring Lattice as a Floquet Topological Insulator
	8.3 Topological Photonic Insulators in 2D Microring Lattices
		8.3.1 2D Microring Lattices as Chern Insulators
		8.3.2 2D Microring Lattices as Floquet Insulators
		8.3.3 Experimental Realization of 2D Floquet Microring Lattices
	8.4 Conclusion
	References
9 Parallel Digital Gradient Search Technique for Rapid Automated Alignment of Devices on Silicon Photonics Integrated Circuits
	9.1 An Application-Driven Challenge
	9.2 Photonics to the Rescue: Energy, Speed, Fidelity, Scalability and Sustainability?
	9.3 Silicon Photonics
	9.4 The Dinosaur Falls: Extinction of the Loops
	9.5 Operating Principle
	9.6 It is 1985 All Over Again: An Ecosystem Rises
	9.7 Down Deep: Implementing the Parallel Alignment
		9.7.1 Area Scans
		9.7.2 Gradient Search
		9.7.3 Example Case: Array Device Alignment
	9.8 Alignment Enables the Quantum Era
	9.9 Conclusion
	References
Part III Advances in Computation Schemes
10 Neuromorphic Silicon Photonics for Artificial Intelligence
	10.1 Introduction
	10.2 Background: Neuroscience and Computation
		10.2.1 Digital Versus Analog
		10.2.2 Artificial Neural Networks
	10.3 Electronics and Photonic Platforms
		10.3.1 Electronics
		10.3.2 Photonics
	10.4 Silicon Photonic Neural Networks
		10.4.1 MZI-based Processing Unit
		10.4.2 Photonic Reservoir Computing
		10.4.3 Broadcast-and-Weight Architecture
	10.5 Summary and Concluding Remarks
	References
11 Quantum Processors in Silicon Photonics
	11.1 Introduction
	11.2 Photonic Quantum Information Processing
		11.2.1 Quantum States of Light
		11.2.2 Encoding Qubits and Qudits in Photons
		11.2.3 Processing Photons with Linear Optics
		11.2.4 Scalable Photonic Quantum Computing Architectures
	11.3 Silicon Quantum Photonic Technology
		11.3.1 Integrated Photon Sources
		11.3.2 Linear-Optical Components
		11.3.3 Detection Systems
		11.3.4 Single-Photon Filters
		11.3.5 Optical and Electronic Packaging
		11.3.6 Scaling Silicon Quantum Photonic Circuits
	11.4 Silicon Photonic Quantum Processors
		11.4.1 Entanglement Generation and Processing in Silicon Photonics
		11.4.2 High-Dimensional Quantum Entanglement in Silicon
		11.4.3 Measurement-Based Quantum Computing in Silicon Quantum Photonics
		11.4.4 Networking Silicon Quantum Devices
	11.5 Applications for Near-Term Photonic Quantum Processors
		11.5.1 Boson Sampling Machines
		11.5.2 Scaling Boson Sampling with Silicon Quantum Photonics
		11.5.3 Quantum Simulation via Boson Sampling
	11.6 Outlook
	References
12 An Open Silicon Photonics Ecosystem for Computercom Applications
	12.1 Introduction
	12.2 Process
	12.3 Design Tools
	12.4 Devices
		12.4.1 Passives
		12.4.2 Active Components
		12.4.3 Lasers
		12.4.4 Detectors
		12.4.5 Packaging
	12.5 Conclusions and Future Work
	References
Index