Towards integrated single-photon sources exploiting inhomogeneous spectral properties of the silicon-vacancy center in nanodiamonds

Due to their favorable optical properties, silicon-vacancy (SiV) centers have recently emerged as promising candidates for the realization of reliable on-demand single photon sources. Such non-classical light sources are key to applications in quantum computing, quantum cryptography, and quantum metrology. In the latter single photon sources are a prerequisite for a quantum-based redefinition of the candela. This thesis contributes to the development of single photon sources with a high applicability in practice through researching SiV centers along two main approaches: First the luminescence properties of a large set of nanodiamonds containing SiV centers are established. This yields a novel strongly inhomogeneous distribution yielding two clusters with regard to the center wavelengths and the linewidth of the zero-phonon-line at room temperature. One of these clusters is consistently explained by strain in the diamond lattice, the other might be due to modified SiV centers. Second, we work towards the goal of developing integrated high-intensity and narrow linewidth single photon sources exploiting the investigated SiV center properties. Using pick-and-place methods, SiV centers are coupled to two different nano-structures. By placing a nanodiamond on top of a vertical-cavity surface emitting laser (VCSEL), we attempt to realize a controllable hybrid-integrated single photon source. By coupling SiV centers with plasmonic nano-antennas we aim to enhance their photoluminescence intensity. We are able to report significant progress towards this goal. Our contributions add momentum to the research of integrated, high-intensity, narrow linewidth single photon sources, to the development of novel calibration standards and ultimately to the universal adoption of the quantum candela.Auf Grund günstiger optischer Eigenschaften sind Silizium Farbzentren (SiV) vielversprechende Kandidaten für die Realisierung von Einzelphotonenquellen. Solche nicht-klassischen Lichtquellen sind für Quantencomputer, Quantenverschlüsselung und Quantenmetrologie essentiell. Für letztere bilden Einzelphotonenquellen eine Schlüsseltechnologie auf dem Weg zu eine quanten-basierte Neudefinition der SIBasiseinheit Candela. Diese Arbeit verfolgt zwei Ansätze um die Entwicklung von Einzelphotonenquellen mit praktischer Bedeutung voranzutreiben: Im ersten Ansatz werden die Lumineszenzeigenschaften einer großen Menge von Nanodiamanten welche SiV Zentren enthalten etabliert. Im Zuge dessen wird eine bisher unbekannte, stark inhomogene Verteilung etabliert, die in zwei Cluster bezüglich der Zentralwellenlänge und Linienbreite der Nullphononenlinie bei Raumtemperatur unterteilt ist. Eines dieser Cluster wird mit Spannungen im Diamantgitter erklärt, das andere könnte aus modifizierten SiV Zentren bestehen. Im zweiten Ansatz arbeiten wir an der Entwicklung von integrierten Einzelphotonenquellen mit hoher Intensität und geringer Linienbreite basierend auf den untersuchten SiV Eigenschaften. Mittels “pick-and-place“ Methoden werden SiV Zentren an verschiedene Nanostrukturen gekoppelt. Durch das platzieren auf einem Oberflächenemitter (VCSEL) versuchen wir eine kontrollierbare hybrid-integrierte Einzelphotonenquelle zu realisieren. Durch die Kombination von Nanodiamanten mit plasmonischen Nanoantennen versuchen wir die Fluoreszenzintensität von enthaltenen SiVs zu verbessern. Es wurden signifikante Fortschritte in Bezug auf beide Ziele erreicht. Unsere Arbeit trägt zur Entwicklung integrierter Einzelphotonenquellen mit hoher Intensität und geringer Linienbreite bei. Dadurch leisten wir einen Beitrag zu Entwicklung neuer Kalibrierungsstandards und damit zur Einführung des Quantencandela

Advances in Optical Amplifiers

Optical amplifiers play a central role in all categories of fibre communications systems and networks. By compensating for the losses exerted by the transmission medium and the components through which the signals pass, they reduce the need for expensive and slow optical-electrical-optical conversion. The photonic gain media, which are normally based on glass- or semiconductor-based waveguides, can amplify many high speed wavelength division multiplexed channels simultaneously. Recent research has also concentrated on wavelength conversion, switching, demultiplexing in the time domain and other enhanced functions. Advances in Optical Amplifiers presents up to date results on amplifier performance, along with explanations of their relevance, from leading researchers in the field. Its chapters cover amplifiers based on rare earth doped fibres and waveguides, stimulated Raman scattering, nonlinear parametric processes and semiconductor media. Wavelength conversion and other enhanced signal processing functions are also considered in depth. This book is targeted at research, development and design engineers from teams in manufacturing industry, academia and telecommunications service operators

Optoelectronics – Devices and Applications

Optoelectronics - Devices and Applications is the second part of an edited anthology on the multifaced areas of optoelectronics by a selected group of authors including promising novices to experts in the field. Photonics and optoelectronics are making an impact multiple times as the semiconductor revolution made on the quality of our life. In telecommunication, entertainment devices, computational techniques, clean energy harvesting, medical instrumentation, materials and device characterization and scores of other areas of R&D the science of optics and electronics get coupled by fine technology advances to make incredibly large strides. The technology of light has advanced to a stage where disciplines sans boundaries are finding it indispensable. New design concepts are fast emerging and being tested and applications developed in an unimaginable pace and speed. The wide spectrum of topics related to optoelectronics and photonics presented here is sure to make this collection of essays extremely useful to students and other stake holders in the field such as researchers and device designers

Subwavelength Grating Based Microcavity and Its Applications in Many-Body Polariton Systems

Semiconductor microcavity polaritons have attracted intense research in the past 20 years because of its deep connections with macroscopic quantum phenomena such as Bose-Einstein condensation (BEC), superfluidity and superconductivity. Experimental polariton systems have evolved as powerful research tools for many-body physics, and have shown promise for novel devices such as ultra-low threshold laser and polaritonic integrated circuit. A central issue to all experimental polariton systems is how to effectively confine and manipulate polaritons. Existing systems all have their limitations such as small modulation depth, destructive to the active medium, and difficult to fabricate or reproduce. In this thesis, we develop a sub-wavelength grating (SWG) based microcavity to generate and control polaritons, which overcomes the limitations of existing systems and has unique properties leading to new physics that was inaccessible before. We demonstrated discrete polariton modes in a fully confined zero dimensional SWG cavity and lasing in the ground state via a thorough set of optical measurements. This shows that the new SWG-cavity can not only support polariton modes but also maintains low loss and allows the formation of coherent polariton condensate. This is the prerequisite of using our system to study macroscopic quantum phenomena and novel many-body physics. Further, polariton nonlinearity was studied from a unique perspective, revealing phenomena contrary to commonly held understanding. Thanks to the polarization anisotropy of the SWG mirror, exciton reservoir of our system can be directly probed through the emission of the weakly-coupled excitons that co-exist with the strongly-coupled polaritons. We show that polariton nonlinearity originate mainly not from exciton energy renormalization, but saturation. The saturation pair density was matched to theoretical values. Reflectance measurements unambiguously show that, at high pump density, excitons already undergo Mott-transition while polariton and polariton lasing is maintained. This is in contrary to previous belief of polariton lasing is realized at far below Mott-density of excitons. Our results point to the light mediated electron-hole binding in a BCS-like state of polaritons. Finally, we demonstrated polariton mode engineering through the design of SWG. Specifically, a SWG is optimized to reduce the mode volume of the cavity, which enhances the coupling strength between excitons and vacuum photons by up to 67% compared to conventional GaAs polariton systems. The larger coupling strength can help increase the operating temperature of polariton systems. Further, SWG cavities with engineered dispersion are demonstrated by designing the angular phase response of SWG mirror. Polariton dispersion is therefore strongly modified, which may enable different polariton dynamics and even exotic quantum orders. As an experimental effort of mode engineering, we demonstrate coupled 0D SWG cavities and quasi-1D polariton lattice. Theoretical modeling using harmonic potential traps and gaussian potential barriers matches well with experiments. The potential depth ranges from 4meV to 20meV. These engineered SWG polariton systems provide an unique venue for research on lattice physics and quantum optical circuits.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138740/1/zrwang_1.pd

The 2017 Terahertz Science and Technology Roadmap

Science and technologies based on terahertz frequency electromagnetic radiation (100GHz-30THz) have developed rapidly over the last 30 years. For most of the 20th century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to “real world” applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2016, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 17 sections that cover most of the key areas of THz Science and Technology. We hope that The 2016 Roadmap on THz Science and Technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies

Analysis and characterization of slab-coupled optical waveguide amplifiers and lasers

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 136-140).Semiconductor optical devices are important in the photonics industry due to their significant advantages in size, weight, and power consumption (SWAP) and to their capability for photonic integration. However, these devices traditionally suffer from low fiber coupling efficiency and have been limited to relatively low power applications. This thesis explores the potential of the slab-coupled optical waveguide (SCOW) semiconductor gain medium for use in high power optical amplifiers and external cavity lasers. The thesis begins by introducing the SCOW concept and describing the benefits of utilizing a low optical confinement design for high power operation. Detailed analysis and measurements of the output power, gain, and noise properties of slab-coupled optical waveguide amplifiers (SCOWAs) and slab-coupled optical waveguide external cavity lasers (SCOWECLs) are also presented. It will be shown that these devices not only exhibit Watt class output power with high coupling efficiency (> 90 %) but also demonstrate the capability for low noise operation.by William Loh.S.M

2D H-polarized Auxiliary Basis Functions for the Extension of the Photonic Wannier Function Expansion for Photonic Crystal Circuitry

Report on accuracy improvements in the numerical computation of localized defect modes (classical light modes) by expanding the wave equations into Wannier functions. Several sets of auxiliary basis functions are suggested which describe non-continuously differentiable magnetic fields in H-polarization properly. Furthermore, improvements of the numerical Souza-Marzari-Vanderbilt Wannier function generation algorithm based on group theoretical analysis are discussed

Magnetic Microtraps for Cavity QED, Bose-Einstein Condensates, and Atom Optics

The system comprised of an atom strongly coupled to photons, known as cavity quantum electrodynamics (QED), provides a rich experimental setting for quantum information processing, both in the implementation of quantum logic gates and in the development of quantum networks. Moreover, studies of cavity QED will help elucidate the dynamics of continuously observed open quantum systems with quantum-limited feedback. To achieve these goals in cavity QED, a neutral atom must be tightly confined inside a high-finesse cavity with small mode volume for long periods of time. Microfabricated wires on a substrate---known as an atom chip---can create a sufficiently high-curvature magnetic potential to trap atoms in the Lamb-Dicke regime. We have recently integrated an optical fiber Fabry-Perot cavity with such a device. The microwires allow the on-chip collection and laser cooling of neutral atoms, and allow the magnetic waveguiding of these atoms to an Ioffe trap inside the cavity mode. Magnetically trapped intracavity atoms have been detected with this cavity QED system. A similar experiment employing microdisks and photonic bandgap cavities is nearing completion. With these more exotic cavities, a robust and scalable atom-cavity chip system will deeply probe the strong coupling regime of cavity QED with magnetically trapped atoms. Atom chips have found great success in producing and manipulating Bose-Einstein condensates and in creating novel atom optical elements. An on-chip BEC has been attained in a miniaturized system incorporating an atom chip designed for atom interferometry and for studies of Josephson effects of a BEC in a double-well potential. Using similar microfabrication techniques, we created and demonstrated a specular magnetic atom mirror formed from a standard computer hard drive. This device, in conjunction with micron-sized charged circular pads, can produce a 1-D ring trap which may prove useful for studying Tonks gases in a ring geometry and for creating devices such as a SQUID-like system for neutral atoms. This thesis describes the fabrication and employment of these atoms chips in experiments at both Caltech and Munich, the latter in collaboration with Professors Theodore Haensch and Jakob Reichel at the Max Planck Institute for Quantum Optics.</p