The G-center has recently been identified as the first deterministic single-photon punctual emitter isolated in silicon. This discovery is of great interest for largescale quantum technologies, due to the abilities of silicon in terms of integration and scalability. However, the spontaneous emission rate of the G-center still needs to be controlled in order to engineer a useful Single-Photon Source. This could be achieved by incorporating a single G-center in resonant microcavities to benefit from the Purcell effect. As a first step in this direction, we have studied in this project micro-cavities containing an ensemble of G-centers, more precisely Si micro-disks and micro-rings on oxide, with several objectives: the evaluation of the quality factor of micro-cavities containing G-centers, the demonstration of an optical activity of G-centers after the processing of the silicon micro-structures, and the evaluation of their potential as gain medium for integrated microlasers on SOI. The observation of bright photoluminescence from G-centers and of resonant cavity modes with Q’s in the few thousands range confirms the compatibility of G-centers with standard silicon processing steps, and is encouraging for future quantum optics experiments on isolated G centers in micro-cavities. Our results also tend to show that gain may be available in the material, but residual absorption still needs to be decreased to achieve lasing. / G-center har nyligen identifierats som den första determinitiska ponctual enfoton källen isolerad i kisel. Denna upptäckt är av stort intresse för kvantteknologier p.g.a. kisels förmåga gällande integration och skalbarhet. G-centers spontana rekombinationshastighet behöver dock kontrolleras för att skapa en användbar enfoton källa. Det kan göras genom Purcell-effekten i en optisk resonator. Som ett första steg har vi studerat mikroresonatorer som innehåller G-center i det presenterade projektet, med flera mål: utvärdering av kvalitetsfaktor för mikroresonatorer som innehåller G-center, demonstration av optisk aktivitet av G-center efter tillverkning av kiselmikrostrukturer, och utvärdering av deras potential för integrerade mikrolaser på SOI. Observation av stark fotoluminescens av G-center och resonatormoder med stor-Q bekräftar kompatibilitet mellan G-center och vanliga steg för bearbetning av kisel, och är uppmuntrande för framtida Kvantum Optik experimenter med isolerade G-center i mikroresonatorer. Resultaten visar att ljusförstärkning troligtvis börjar, men absorption av andra defekter måste minskas för att uppnå laserregim.

[EN] Optical technologies are the backbone of modern communication systems providing high-speed access to the Internet, efficient inter and intra-data center interconnects and are expending towards growing research fields and new markets such as satel- lite communications, LIDARs (Laser Imaging Detection and Ranging) applications, Neuromorphic computing, and programable photonic circuits, to name a few. Be- cause of its maturity and low-cost, silicon photonics is being leveraged to allow these new technologies to reach their full potential.As a result, there is a strong need for innovative, high-speed and energy-efficient photonic integrated building blocks on the silicon platform to increase the readiness of silicon photonic integrated circuits. The work developed and presented in this thesis is focused on the design and char- acterization of advanced passive and active devices, for photonic integrated circuits. The thesis consists of three main chapters as well as a motivation and concluding sections exposing the rationale and the accomplishments of this work. Chapter one describes the design and characterization of an electro-optical Mach-Zehnder mod- ulator embedded in highly efficient vertical pn junction exploiting the free-carrier dispersion effect in the O-band.. Chapter two is devoted to the design and charac- terization of a novel geometry of asymmetrical multimode interference device and its implementation in a Mach-Zehnder modulator. Chapter three is dedicated to the design and characterization of innovative 1-dimensional photonic crystal designs for slow- lightmodulation applications. An extensive analysis of the main trade-off arising from the use of slow light is presented. / [ES] Las tecnologías ópticas son el eje vertebrador de los sistemas de comunicación mod- ernos que proporcionan acceso de alta velocidad a la Internet, interconexiones efi- cientes entre centros de datos y dentro de ellos. Además, se están expandiendo hacia campos de investigación crecientes y nuevos mercados como son las aplicaciones de comunicaciones por satélite, los LIDAR (Laser Imaging Detection and Ranging), la computación neuromórfica y los circuitos fotónicos programables, por nombrar algunos. La fotónica de silicio está considerada y aceptada ampliamente como una de las tecnologías clave para que dichas aplicaciones puedan desarrollarse. Como resultado, hay una fuerte necesidad de estructuras fotónicas básicas integradas que sean innovadoras, que soporten altas velocidades de transmisión y que sean más eficientes en términos de consumo de potencia, a fin de aumentar la capacidad de los circuitos integrados fotónicos de silicio. El trabajo desarrollado y presentado en esta tesis se centra en el diseño y la car- acterización de dispositivos avanzados pasivos y activos, para circuitos fotónicos integrados. La tesis consta de tres capítulos principales, así como de sendas sec- ciones de motivación y conclusiones que exponen los fundamentos y los logros de este trabajo. El capítulo uno describe el diseño y la caracterización de un modulador electro-óptico Mach-Zehnder incorporado en una unión pn vertical altamente eficien- ciente que explota el efecto de dispersión de plasma en banda O. El capítulo dos está dedicado al diseño y caracterización de una nueva geometría de dispositivo de interferencia multimodo asimétrico y su aplicación en un modulador Mach-Zehnder. El capítulo tres está dedicado al diseño y caracterización de innovadores cristales fotónicos unidimensionales para aplicaciones de modulación con luz lenta. Se pre- senta un amplio análisis de los principales retos derivados del uso de la misma. / [CA] Les tecnologies òptiques són l'eix vertebrador d'aquells sistemes de comunicació moderns que proporcionen accés d'alta velocitat a la Internet, així com intercon- nexions eficients inter i entre centres de dades. A més a més, s'estan expandint cap a camps d'investigació creixents i nous mercats com són les aplicacions de co- municacions per satèl·lit, els LIDAR (Laser Imaging Detection and Ranging), la computació neuromòrfica i els circuits fotònics programables, entre d'altres. La fotònica de silici és considerada i acceptada àmpliament com una de les tecnologies clau i necessàries perquè aquestes aplicacions puguen desenvolupar-se. Per aquest motiu, es fa necessària l'existència d'estructures fotòniques bàsiques integrades que siguen innovadores, que suporten altes velocitats de transmissió i que siguen més eficients en termes de consum de potència, a fi d'augmentar la capacitat dels cir- cuits integrats fotònics de silici. El treball desenvolupat i presentat en aquesta tesi se centra en el disseny i la caracterització de dispositius avançats passius i actius, per a circuits fotònics integrats. La tesi consta de tres capítols principals, així com d'una secció de motivació i una altra de conclusions que exposen els fonaments i els assoliments d'aquest treball. El capítol u descriu el disseny i la caracterització d'un modulador electro-òptic Mach-Zehnder incorporat en una unió pn vertical d'alta efi- ciència que explota l'efecte de dispersió de plasma en la banda O. El capítol dos està dedicat al disseny i caracterització d'una nova geometria de dispositiu d'interferència multimode asimètric així com a la seua aplicació en un modulador Mach-Zehnder. El capítol tres està dedicat al disseny i caracterització d'innovadors cristalls fotònics unidimensionals per a aplicacions de modulació amb llum lenta. S'inclou també una anàlisi detallada dels principals reptes derivats de l'ús d'aquest tipus de llum. / I want to thank you the Generelitat Valenciana and the European Project L3MATRIX for the funding, without them my doctorate would not taken place. / Zanzi, A. (2020). Passive and active silicon photonics devices at TLC telecommunication wavelengths for on-chip optical interconnects [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149377 / TESIS

Silicon photonics has been a rapidly growing subfield of integrated optics and optoelectronic in the last decade and is currently considered a mature technology. The main thrust behind the growth is its compatibility with the mature and low-cost microelectronic integrated circuits fabrication process. In recent years, several active and passive photonic devices and circuits have been demonstrated on silicon. Optical delay lines are among important silicon photonic devices, which are essential for a variety of photonic system applications including optical beam-forming for controlling phased-array antennas, optical communication and networking systems and optical coherence tomography. In this thesis, several types of delay lines based on apodized grating waveguides are proposed and demonstrated. Simulation and experimental results suggest that these novel devices can provide high optical delay and tunability at very high bit rate. While most of silicon photonics research has focused in the near-infrared wavelengths, extending the operating wavelength range of the technology into in the 3–5 µm, or the mid-wave infrared regime, is a more recent field of research. A key challenge has been that the standard silicon-on-insulator waveguides are not suitable for the midinfrared, since the material loss of the buried oxide layer becomes substantially high. Here, the silicon-on-sapphire waveguide technology, which can extend silicon’s operating wavelength range up to 4.4 µm, is investigated. Furthermore, silicon-on-nitride waveguides, boasting a wide transparent range of 1.2–6.7 μm, are demonstrated and iv characterized for the first time at both mid-infrared (3.39 μm) and near-infrared (1.55 μm) wavelengths.

Silicon photonics (SiP) has evolved into a mature platform for cost-effective low power compact integrated photonic microsystems for many applications. There is a looming capacity crunch for telecommunications infrastructure to overcome the data-hungry future, driven by streaming and the exponential increase in data traffic from consumer-driven products. To increase data capacity, researchers are now looking at the wavelength window of the thulium-doped fiber amplifier (TDFA), centered near 2 µm as an attractive new transmission window for optical communications, motivated by the demonstrations of low loss, low nonlinearity, and high bandwidth transmission. Large-scale implementation of SiP telecommunication infrastructure will require light sources (lasers) and amplifiers to generate signals and boost transmitted and/or received signals, respectively. Silicon (Si) and silicon nitride (Si3N4) have become the leading photonic integrated circuit (PIC) material platforms, due to their low-cost and wafer-scale production of high-performance circuits. Silicon does however have a number of limitations as a photonic material, including that it is not an ideal light-emitting/amplifying material. This proposed research pertains to the fabrication of on-chip silicon and silicon nitride lasers and amplifiers to be used in a newly accessible optical communications window of the TDFA band, which is a significant step towards compact PICs for the telecommunication networks. Tellurium oxide (TeO2) is an interesting host material due to its large linear and non-linear refractive indices, low material losses and large rare-earth dopant solubility showing good performance for compact low-loss waveguides and on-chip light sources and amplifiers. Chapter 1 provides an overview of silicon photonics in the context of particularly rare earth lasers and amplifiers, operating at extended wavelengths enabled by the Thulium doped fiber amplifier. Chapter 2 presents a theoretical performance of waveguides and microresonators as the efficient structure for laser and amplifiers applications designed for optimized use in Erbium and Thulium doped fiber amplifier wavelength bands. Then spectroscopic study thulium (Tm3+) has been studied as the rare earth element for Thulium doped fiber amplifier wavelength bands. Chapter 3 presents an experimental study of TeO2:Tm3+ coated Si3N4 waveguide amplifiers with internal net gains of up to 15 dB total in a 5-cm long spiral waveguide. Chapter 4 provides a study of TeO2:Tm3+ -coated Si3N4 waveguide lasers with up to 16 mW double-sided on-chip output power. Chapter 5 presents an experimental study of low loss and high-quality factor silicon microring resonators coated with TeO2 for active, passive, and nonlinear applications. Chapter 6 represents the first demonstration of an integrated rare-earth silicon laser, with high performance, including single-mode emission, a lasing threshold of 4 mW, and bidirectional on-chip output powers of around 1 mW. Further results with a different design are presented showing lasers with more than 2 mW of double-sided on-chip output power, threshold pump powers of < 1 mW and lasing at wavelengths over a range of > 100 nm. Importantly, a simple, low-cost design was used which is compatible with silicon photonics foundry processes and enables wafer scale integration of such lasers in SiP PICs using robust materials. Chapter 7 summarizes the thesis and provides paths for future work. / Dissertation / Doctor of Engineering (DEng)

No description available.

<p>A glass-clad, slow-light photonic-crystal waveguide is proposed as a solution to sub-bandgap light detection in silicon photonic circuits. Such detection in silicon is perceived as a challenge owing to silicon's indirect band gap and transparency to 1550nm wavelengths, yet is essential for achieving low-cost, high-yield integration with today's microelectronics industry. Photonic crystals can be engineered in such a way as to enhance light-matter interaction over a specific bandwidth via the reduction of the group velocity of the propagating wave (i.e. the slowing of light). The interaction enhanced for light detection in the present work is electron-hole pair generation at defect sites. The intrinsic electric field of a p-i-n junction enables light detection by separating the electron-hole pairs as a form of measurable current. The photonic-crystal waveguides are designed to have bandwidths in the proximity of a wavelength of 1550nm. Refractive indices of over 80 near the photonic-crystal waveguide's Brillouin zone boundary are measured using Fourier transform spectral interferometry and are found to correspond to numerical simulations. Defect-induced propagation loss was seen to scale with group index, from 400dB/cm at a group index of 8 to 1200dB/cm at a group index of 88. Scaling was sublinear, which is believed to be due to the spreading of modal volume at large group index values. Photodetectors were measured to have responsivities as high as 34mA/W near the photonic-crystal waveguide's Brillouin zone boundary for a reverse bias of 20V and a remarkably short detector length of 80um. The fabrication of each device is fully CMOS-compatible for the sake of cost-effective integration with silicon microelectronics.</p> / Master of Applied Science (MASc)

Optical interconnects based on CMOS compatible photonic integrated circuits are regarded as a promising technique to tackle the issues traditional electronics faces, such as limited bandwidth, latency, vast energy consumption and so on. In recent years, plasmonic integrated components have gained great attentions due to the properties of nano-scale confinement, which may potentially bridge the size mismatch between photonic and electronic circuits. Based on silicon nanowire platform, this thesis work studies the design, fabrication and characterization of several integrated plasmonic components, aiming to combine the benefits of Si and plasmonics. The basic theories of surface plasmon polaritons are introduced in the beginning, where we explain the physics behind the diffraction-free confinement. Numerical methods frequently used in the thesis including finite-difference time-domain method and finite-element method are then reviewed. We summarize the device fabrication techniques such as film depositions, e-beam lithography and inductively coupled plasma etching as well as characterization methods, such as direct measurement method, butt coupling, grating coupling etc. Fabrication results of an optically tunable silicon-on-insulator microdisk and III-V cavities in applications as light sources for future nanophotonics interconnects are briefly discussed. Afterwards we present in details the experimental demonstrations and novel design of plasmonic components. Hybrid plasmonic waveguides and directional couplers with various splitting ratios are firstly experimentally demonstrated. The coupling length of two 170 nm wide waveguides with a separation of 140 nm is only 1.55 µm. Secondly, an ultracompact polarization beam splitter with a footprint of 2×5.1 μm2 is proposed. The device features an extinction ratio of 12 dB and an insertion loss below 1.5 dB in the entire C-band. Thirdly, we show that plasmonics offer decreased bending losses and enhanced Purcell factor for submicron bends. Novel hybrid plasmonic disk, ring and donut resonators with radii of ~ 0.5 μm and 1 μm are experimentally demonstrated for the first time. The Q-factor of disks with 0.5 μm radii are                         , corresponding to Purcell factors of . Thermal tuning is also presented. Fourthly, we propose a design of electro-optic polymer modulator based on plasmonic microring. The figure of merit characterizing modulation efficiency is 6 times better comparing with corresponding silicon slot polymer modulator. The device exhibits an insertion loss below 1 dB and a power consumption of 5 fJ/bit at 100 GHz. At last, we propose a tightly-confined waveguide and show that the radius of disk resonators based on the proposed waveguide can be shrunk below 60 nm, which may be used to pursue a strong light-matter interaction. The presented here novel components confirm that hybrid plasmonic structures can play an important role in future inter- and intra-core computer communication systems. / <p>QC 20140404</p>

Cette thèse a pour objectif ultime d'améliorer notre compréhension de la réflexion de la lumière sur des surfaces micro-courbes, en particulier lorsque les dimensions physiques des surfaces (rayons de courbure de l'ordre de 50-300 μm) sont comparables aux paramètres dimensionnels d'un faisceau optique Gaussien, typique des faisceaux issus d'une fibre optique ou d'un microlaser. A cet effet, une étude théorique et des simulations numériques ont été menées ; elles ont été confrontées à une étude expérimentale. Pour ce faire, la réalisation des micro-miroirs à concavité contrôlée n'étant pas chose aisée, un premier jalon de cette thèse a consisté à atteindre les avancées technologiques nécessaires à la réalisation de tels micro-miroirs(par procédé de gravure plasma de type DRIE) en vue de leur caractérisation expérimentale. Une motivation importante du choix de ce sujet est son potentiel applicatif à la réalisation de micro-bancs optiques sur puce silicium, de sorte à augmenter les capacités de couplage et de manipulation de lumière de façon intégrée dans un espace ultra-compact. A titre d'illustration des possibilités de la nouvelle micro-instrumentation optique que nous proposons, nous avons conçu et réalisé un microsystème de balayage spatial à grand angle (110°) d'un faisceau laser dont le spot optique ne se déforme pas tout au long de l'opération de balayage, ce qui en fait, entre autres, la pièce maîtresse de systèmes portables d'imagerie médicale par tomographie à cohérence optique / The ultimate objective of this thesis is to improve our understanding of light reflection on micro-curved surfaces, especially when the physical dimensions of the surfaces (radii of curvature in the order of 50-300 microns) are comparable to typical dimensional parameters of a Gaussian optical beam, such as those coming from an optical fiber or from a micro-laser. To this end, a theoretical study and numerical simulations were conducted; they were confronted with an experimental study. To do this, the realization of micro-mirrors controlled concavity being not easy, a first step of this thesis was to achieve the technological advances necessary for the realization of such micro-mirrors (by plasma etching method of DRIE type) for their subsequent experimental characterization. An important motivation for choosing this topic is its potential application in the production of micro-optical benches on a silicon chip, so as to increase the coupling efficiencies and capabilities of manipulation of light, in an integrated way and in an ultra compact space. As an illustration of the new micro-optical instrumentation which is attainable, we have designed and implemented a micro-device able of wide-angle (110 °) spatial scanning of a laser beam, the optical spot being not deformed during the scanning operation, which makes this device, the centerpiece of portable medical imaging systems by optical coherence tomography, among others

In den letzten Jahren gibt es großes Interesse am SiGeSn Materialsystem aufgrund seines Potentials für die Verwendung in der Optoelektronik, Elektronik und Photovoltaik. Während jedoch die binären Verbindungshalbleiter Si(x)Ge(1-x) und Ge(1-y)Sn(y) schon intensiv untersucht wurden, sind die Materialeigenschaften des ternären Verbindungshalbleiters Ge(1-x-y)Si(x)Sn(y) und Nanostrukturen basierend auf diesem Verbindungshalbleiter noch weitgehend unbekannt. In dieser Arbeit werden drei theoretische/theoretisch-experimentelle Studien zur Untersuchung des SiGeSn Materialsystems vorgestellt. In einer Studie wird die Abhängigkeit der Größe der direkten Bandlücke von der Zusammensetzung des Ge(1-x-y)Si(x)Sn(y) Verbindungshalbleiters untersucht. Basierend auf Messungen der Rutherford Rückstreuung, Röntgenbeugung und Photolumineszenz (PL) von Ge(1-x-y)Si(x)Sn(y) Proben mit an Ge angepassten Gitterkonstanten wird die Abhängigkeit von Größe der direkten Bandlücke und der Materialkomposition mit einer quadratischen Gleichung beschrieben. Weiterhin wird die Bandanordnung der elementaren Halbleiter Si, Ge und Sn an Grenzflächen untersucht. Anhand von Kohn-Sham basierter Density Functional Theory (DFT) in Kombination mit Local Density Approximation (LDA) berechneten Bandstrukturen von Grenzflächen zwischen Elementarhalbleitern wird der Versatz im Valenzband zwischen Si, Ge und Sn untersucht. Es wird gezeigt, dass aufgrund zu kleiner Bandlücken resultierend aus dem Kohn-Sham-Ansatz in Verbindung mit der LDA ein unphysikalischer „Broken Gap“ Versatz zwischen Ge und Sn Bändern entsteht. In einer dritten Studie werden die PL-Spektren von Ge Quantentöpfen mit Si Barrieren untersucht. Um die Abhängigkeit der PL-Spektren von Anregungsintensität und Temperatur zu verstehen, wird ein selbstkonsistentes Effektives-Massen-Model entwickelt. Mit diesem Model ist es möglich den Einfluss von Temperatur und Bandauffüllung auf das PL-Spektrum zu untersuchen. / The SiGeSn semiconductor material system has recently attracted great interest due to its prospective potential for use in optoelectronics, electronics, and photovoltaics. While the binary alloy Si(x)Ge(1-x) and Ge(1-y)Sn(y) have already been well studied, the properties of bulk and heterostructures involving the Ge(1-x-y)Si(x)Sn(y) ternary alloy are largely unknown. In this thesis, we present the results of three theoretical/experimental-theoretical investigations concerning the SiGeSn material system. First, we investigate the compositional dependence of the direct band-gap of Ge(1-x-y)Si(x)Sn(y) alloys. Based on Rutherford backscattering, x-ray diffraction, and photoluminescence (PL) measurement of Ge(1-x-y)Si(x)Sn(y) alloys lattice-matched to Ge, we describe the compositional dependence of the band gap using a quadratic equation. We predict Ge(1-x-y)Si(x)Sn(y) alloys lattice-matched to Ge to be direct-band-gap semiconductors for Sn concentrations larger than 12%. Secondly, we investigate the band alignment between the elemental semiconductors Si, Ge, and Sn. Performing bulk and interface calculations using density functional theory (DFT) in combination with the local density approximation (LDA), we attempt to calculate the valence band offset between the elemental semiconductors. We find that the Kohn-Sham based DFT-LDA calculations are flawed by the underestimation of the band-gaps of the elemental semiconductors, which leads to a false broken gap band alignment between Ge and Sn. Third, we study the PL of ultrathin Ge multiple quantum well (multiple-QW) structures grown on Si. To understand the excitation density and temperature related shifts of the PL spectra of the sample, we develop a self-consistent multivalley effective mass model. Using second-order perturbation theory, we calculate the indirect phonon-assisted radiative spontaneous recombination rate together with the no-phonon peak energy and compare our results to the experimental results.

Le germanium dopé n et contraint en tension est un candidat potentiel pour démontrer un laser sur silicium compatible avec un environnement CMOS. Dans ce travail de thèse, j’ai d’abord développé un formalisme qui permet de calculer le gain optique en fonction de la déformation en tension, du dopage n et de l’injection des porteurs. Une technique de transfert de déformation via le dépôt de couche contrainte de SiN a été optimisée. J’ai réalisé plusieurs types de cavités germanium contraintes sous forme de guides d’onde et de microdisques. Le transfert de déformation a été optimisé par sous-gravure et par une méthode de bi-encapsulation qui a permis d’aboutir à une déformation biaxiale homogène et élevée de l’ordre de 1.5%. L’évaluation des déformations a été confrontée à des simulations par éléments finis, photoluminescence et spectroscopie Raman. L’étude expérimentale et théorique des guides d’onde a montré l’avantage de la direction <100> par rapport à la direction <110> permettant une injection plus efficace de porteurs en centre de zone. L’étude expérimentale des microdisques a permis d’observer des modes de galerie avec un facteur de qualité Q = 1540 à λ = 1940 nm. D’autre part, j’ai mis en évidence par photoluminescence la présence d’un fort dopage de 4×10¹⁹ cm⁻³ dans des couches germanium sur silicium épitaxiées par épitaxie par jets moléculaires utilisant une technique de co-dopage. Une modélisation du gain modal a permis de mettre en exergue l’effet du gradient de déformation dans le volume de la cavité. L’élargissement homogène a été introduit dans la modélisation du gain optique afin de prendre en compte l’impact d’un dopage élevé. / Tensile strained and n-doped germanium is a potential candidate to demonstrate a laser on silicon in a CMOS-compatible environment. In this thesis, I developed a formalism to calculate the optical gain as a function of tensile strain, n-doping and carrier injection. A tensile strain transfer technique via strained SiN layer deposition has been optimized. I realized several types of strained germanium cavities. Tensile strain transfer was optimized by under-etching and a bi-encapsulation technique which allowed to achieve a high and uniform biaxial strain up to 1.5%. The evaluation of strain level was faced with finite elements modeling, photoluminescence and Raman spectroscopy. The experimental and theoretical study of the waveguides showed the advantage of the <100> direction as compared with the <110> direction for more efficient carrier injection at zone center. The experimental study of microdisks allowed us to observe gallery modes with quality factor up to Q = 1540 at λ= 1940 nm. On the other hand, photoluminescence enhancement has shown the presence of a heavy doping of 4×10¹⁹ cm⁻³ in germanium on silicon layers grown by molecular beam epitaxy and using a co-doping technique. Modeling the modal gain helped to emphasize the effect of the strain gradient in the cavity volume. The homogeneous broadening was introduced in the optical gain modeling to take into account the impact of a high doping.