Ce travail vise à concevoir un modulateur optique assisté par plamsons, compatible CMOS et à faible consommation électrique. L’électro-absorption, basée sur l’effet Franz-Keldysh dans le germanium, a été choisie comme principe de modulation pour réduire la taille du dispositif et la consommation d'énergie électrique associée. L’effet Franz-Keldysh se traduit par un changement du coefficient d'absorption du matériau près du bord de bande sous l'application d'un champ électrique statique, d'où la production d'une modulation directe de l'intensité lumineuse. L'utilisation de plasmons permet en principe d’augmenter l'effet électro-optique en raison du fort confinement du mode optique. Un outil de simulation électro-optique intégré a été développé pour concevoir et optimiser le modulateur. Le modulateur plasmonique proposé a un taux d'extinction de 3.3 dB avec des pertes d'insertion de 11.2 dB et une consommation électrique de seulement 20 fJ/bit, soit la plus faible consommation électrique décrite pour les modulateurs photoniques sur silicium. Le couplage du modulateur à un guide silicium standard en entrée et en sortie a également été optimisé par l’introduction d'un adaptateur de mode Si-Ge optimisé, réduisant les pertes de couplage à seulement 1 dB par coupleur. Par ailleurs, un travail expérimental a été effectué pour tenter de déplacer l'effet Franz-Keldysh, maximum à 1650 nm, à de plus faibles longueurs d'onde proches de 1.55 μm pour des applications aux télécommunications optiques. / This work aims to design a CMOS compatible, low-electrical power consumption modulator assisted by plasmons. For compactness and reduction of the electrical power consumption, electro-absorption based on the Franz-Keldysh effect in Germanium was chosen for modulation. It consists in the change of the absorption coefficient of the material near the band edge under the application of a static electric field, hence producing a direct modulation of the light intensity. The use of plasmons allows enhancing the electro-optical effect due to the high field confinement. An integrated electro-optical simulation tool was developed to design and optimize the modulator. The designed plasmonic modulator has an extinction ratio of 3.3 dB with insertion losses of 13.2 dB and electrical power consumption as low as 20 fJ/bit, i.e. the lowest electrical power consumption reported for silicon photonic modulators. In- and out-coupling to a standard silicon waveguide was also engineered by the means of an optimized Si-Ge taper, reducing the coupling losses to only 1 dB per coupler. Besides, an experimental work was carried out to try to shift the Franz-Keldysh effect, which is maximum at 1650 nm, to lower wavelength close to 1.55 μm for telecommunication applications.

The objective of this work presented here is to extend the capabilities of siloxane waveguide technology in the field of biochemical sensing. Recent advances in the integration of polymeric optical waveguides with electronics onto standard printed circuit boards (PCBs) allow the formation of cost-effective lab-on-achip modules suitable for mass production. This technology has been primarily designed for on-board data communication. The focus of this research is to investigate the possibility of realising a Siloxane polymer based lab-on-chip sensor. Different siloxane-polymer-based optical waveguide sensor structures have been designed and analysed from the aspect of biochemical sensing. An evanescent-wave absorption sensor based on mode-selective asymmetric waveguide junctions is proposed for the first time. The device mitigates the common optical effect of spurious response in absorption sensors due to the analyte transport fluid. Head injury is the leading cause of death in the population of people under 40 years. Currently, 3 out of 5 deaths in emergency rooms are due to severe brain injuries in the developed world. Researchers at the Neurosciences Critical Care Unit (NCCU) at Addenbrooke's Hospital have managed to correlate biochemical changes with the severeness of the injury and the likelihood of patient recovery. Considerable progress has been made to develop a lab-on-chip sensor capable of continuously monitoring glucose, lactate and pyruvate concentrations in the brain fluid, hence the contribution to the current trend in the advancement of portable lab-on-chip technologies for the deployment of point-of-care diagnostic tools. A novel recognition layer has been developed based on porphyrin in combination with glucose, lactate and pyruvate oxidase for measuring all the analytes, enabling fast and reversible chemical reactions to be monitored by optical interrogation. The operational wavelength of the developed recognition layer is 425 nm, which required the formation of polymer features that were beyond the fabrication capabilities at the time. Through considerable process development and the adoption of nanoimprinting lithography, siloxane polymer based optical waveguides were fabricated allowing the realisation of highly sensitive optical sensors. Based on the results that are presented here, it can be concluded the functionalization of siloxane polymer waveguide have a potential for realising biochemical sensors in the future. The new fabrication technique will allow the formation of more robust and complex lab-on-chip sensors based on this material.

Cette thèse explore certaines possibilités qu’offre l’optique intégrée en silicium pour des applications en ingénierie quantique. Un premier chapitre établi la théorie de la propagation non linéaire scalaire du champ électrique dans des guides d’onde en silicium. La génération de paires dans de tels guides est également présentée. Le second chapitre reprend un travail expérimental de caractérisation des propriétés non linéaires des guides utilisés. Le résultat original principal de ce travail est un montage de caractérisation non linéaire par la méthode D-scan en régime picoseconde. Le coeur du travail est présentée dans le troisième chapitre, il s'agit de la mise en évidence, la caractérisation et de l'étude approfondie de la génération de paires de photons au sein de guides d’ondes. Le dernier chapitre est consacré à l’intégration proprement dite de la source de paires de photons au sein d’un circuit quantique afin de réaliser la majeure partie d’un expérience clé d’optique quantique sur une puce en silicium. Nous présentons deux sources de paires de photons prêtes pour l'intégration avec un circuit optique (paires en cavité et filtration spectrale). Nous présentons ensuite la préparation d'expériences intégrées préliminaires. En particulier, nous montrons l'enchevêtrement en chemin produit dans une structure intégrée. Nous réalisons également l'expérience de Hong-Ou-Mandel.

The Photonic Crystal (PC) is a potential candidate for a compact optical integrated circuit on a solid state platform. The fabrication process of a PC is compatible with CMOS technology; thus, it could be potentially employed in hybrid optical and electrical integrated circuits. One of the main obstacles in the implementation of an integrated optical circuit is the polarization dependence of wave propagation. Our goal is to overcome this obstacle by implementing PC based polarization controlling devices. One of the crucial elements of polarization controlling devices is the polarization rotator. The polarization rotator is utilized to manipulate and rotate the polarization of light. In this thesis, we have proposed, designed and implemented an ultra-compact passive PC based polarization rotator. Passive polarization rotator structures are mostly composed of geometrically asymmetric structures. The polarization rotator structure consists of a single defect line PC slab waveguide. The geometrical asymmetry has been introduced on top of the defect line as an asymmetric loaded layer. The top loaded layer is asymmetric with respect to the z-axis propagation direction. To synchronize the power conversion and avoid power conversion reversal, the top loaded layer is alternated around the z-axis periodically. The structure is called periodic asymmetric loaded PC slab waveguide. Due to the compactness of the proposed structure, a rigorous numerical method, 3D-FDTD can be employed to analyze and simulate the final designed structure. For the quick preliminary design, an analytical method that provides good approximate values of the structural parameters is preferred. Coupled-mode theory is a robust and well-known method for such analyses of perturbed waveguide structures. Thus, a coupled-mode theory based on semi-vectorial modes was developed for propagation modeling on square hole PC structures. In essence, we wish to develop a simple yet closed form method to carry out the initial design of the device of interest. In the next step, we refined the design by using rigorous but numerically expensive 3D-FDTD simulations. We believe this approach leads to optimization of the device parameters easily, if desired. To extend the design to a more general shape PC based polarization rotator, a design methodology based on hybrid modes of asymmetric loaded PC slab waveguide was introduced. The hybrid modes of the structure were calculated utilizing the 3D-FDTD method combined with the Spatial Fourier Transform (SFT). The propagation constants and profile of the slow and fast modes of an asymmetric loaded PC slab waveguide were extracted from the 3D-FDTD simulation results. The half-beat length, which is the length of each loaded layer, and total number of the loaded layers are calculated using the aforementioned data. This method provides the exact values of the polarization rotator structure’s parameter. The square hole PC based polarization rotator was designed employing both coupled-mode theory and normal modal analysis for THz frequency applications. Both design methods led to the same results. The design was verified by the 3D-FDTD simulation of the polarization rotator structure. For a square hole PC polarization rotator, a polarization conversion efficiency higher than 90% over the propagation distance of 12 λ was achieved within the frequency band of 586.4-604.5 GHz corresponding to the normalized frequency of 0.258-0.267. The design was extended to a circular hole PC based polarization rotator. A polarization conversion efficiency higher than 75% was achieved within the frequency band of 600-604.5 GHz. The circular hole PC polarization rotator is more compact than the square-hole PC structure. On the other hand, the circular hole PC polarization rotator is narrow band in comparison with the square hole PC polarization rotator. In a circular hole PC slab structure, the Bloch modes (fast and slow modes) couple energy to the TM-like PC slab modes. In both square and circular hole PC slab structures with finite number of rows, and the TM-like PC slab modes are extended to the lower edge of the bandgap. In bandgap calculation using PWEM, it is assumed that the PC structure is extended to infinity, however in practice the number of rows is limited, which is the source of discrepancy between the bandgap calculation using PWEM and 3D-FDTD. In an asymmetric loaded circular hole PC slab waveguide, the leaky TM-like PC slab modes are extended deep inside the bandgap and overlapped with both the slow and fast Bloch modes; whereas, in an asymmetric loaded square hole PC slab waveguide, the leaky TM-like PC slab modes are below the frequency band of slow and fast modes. Therefore, TM-like PC slab modes have significantly more adverse effect on the performance of the circular-hole based polarization rotator leading to a narrow band structure. SOI based PC membrane technology for THz application was developed. The device layer is made of highly resistive silicon to maintain low loss propagation for THz wave. The PC slab waveguide and polarization rotators were fabricated employing this technology. Finally, an a-SiON PC slab waveguide structures were also fabricated at low temperature for optical applications. This technology has the potential to be implemented on any substrate or CMOS chips.

The Photonic Crystal (PC) is a potential candidate for a compact optical integrated circuit on a solid state platform. The fabrication process of a PC is compatible with CMOS technology; thus, it could be potentially employed in hybrid optical and electrical integrated circuits. One of the main obstacles in the implementation of an integrated optical circuit is the polarization dependence of wave propagation. Our goal is to overcome this obstacle by implementing PC based polarization controlling devices. One of the crucial elements of polarization controlling devices is the polarization rotator. The polarization rotator is utilized to manipulate and rotate the polarization of light. In this thesis, we have proposed, designed and implemented an ultra-compact passive PC based polarization rotator. Passive polarization rotator structures are mostly composed of geometrically asymmetric structures. The polarization rotator structure consists of a single defect line PC slab waveguide. The geometrical asymmetry has been introduced on top of the defect line as an asymmetric loaded layer. The top loaded layer is asymmetric with respect to the z-axis propagation direction. To synchronize the power conversion and avoid power conversion reversal, the top loaded layer is alternated around the z-axis periodically. The structure is called periodic asymmetric loaded PC slab waveguide. Due to the compactness of the proposed structure, a rigorous numerical method, 3D-FDTD can be employed to analyze and simulate the final designed structure. For the quick preliminary design, an analytical method that provides good approximate values of the structural parameters is preferred. Coupled-mode theory is a robust and well-known method for such analyses of perturbed waveguide structures. Thus, a coupled-mode theory based on semi-vectorial modes was developed for propagation modeling on square hole PC structures. In essence, we wish to develop a simple yet closed form method to carry out the initial design of the device of interest. In the next step, we refined the design by using rigorous but numerically expensive 3D-FDTD simulations. We believe this approach leads to optimization of the device parameters easily, if desired. To extend the design to a more general shape PC based polarization rotator, a design methodology based on hybrid modes of asymmetric loaded PC slab waveguide was introduced. The hybrid modes of the structure were calculated utilizing the 3D-FDTD method combined with the Spatial Fourier Transform (SFT). The propagation constants and profile of the slow and fast modes of an asymmetric loaded PC slab waveguide were extracted from the 3D-FDTD simulation results. The half-beat length, which is the length of each loaded layer, and total number of the loaded layers are calculated using the aforementioned data. This method provides the exact values of the polarization rotator structure’s parameter. The square hole PC based polarization rotator was designed employing both coupled-mode theory and normal modal analysis for THz frequency applications. Both design methods led to the same results. The design was verified by the 3D-FDTD simulation of the polarization rotator structure. For a square hole PC polarization rotator, a polarization conversion efficiency higher than 90% over the propagation distance of 12 λ was achieved within the frequency band of 586.4-604.5 GHz corresponding to the normalized frequency of 0.258-0.267. The design was extended to a circular hole PC based polarization rotator. A polarization conversion efficiency higher than 75% was achieved within the frequency band of 600-604.5 GHz. The circular hole PC polarization rotator is more compact than the square-hole PC structure. On the other hand, the circular hole PC polarization rotator is narrow band in comparison with the square hole PC polarization rotator. In a circular hole PC slab structure, the Bloch modes (fast and slow modes) couple energy to the TM-like PC slab modes. In both square and circular hole PC slab structures with finite number of rows, and the TM-like PC slab modes are extended to the lower edge of the bandgap. In bandgap calculation using PWEM, it is assumed that the PC structure is extended to infinity, however in practice the number of rows is limited, which is the source of discrepancy between the bandgap calculation using PWEM and 3D-FDTD. In an asymmetric loaded circular hole PC slab waveguide, the leaky TM-like PC slab modes are extended deep inside the bandgap and overlapped with both the slow and fast Bloch modes; whereas, in an asymmetric loaded square hole PC slab waveguide, the leaky TM-like PC slab modes are below the frequency band of slow and fast modes. Therefore, TM-like PC slab modes have significantly more adverse effect on the performance of the circular-hole based polarization rotator leading to a narrow band structure. SOI based PC membrane technology for THz application was developed. The device layer is made of highly resistive silicon to maintain low loss propagation for THz wave. The PC slab waveguide and polarization rotators were fabricated employing this technology. Finally, an a-SiON PC slab waveguide structures were also fabricated at low temperature for optical applications. This technology has the potential to be implemented on any substrate or CMOS chips.

Photonic crystals have allowed unprecedented control of light and have allowed bringing new functionalities on chip. Photonic crystal waveguides (PCWs), which are linear defects in a photonic crystal, have unique features that distinguish these waveguides from other waveguides. The unique features include very large dispersion, existence of slow light, and the possibility of tailoring the dispersion properties for guiding light. In my research, I have overcome some of the challenges in using slow light in PCWs. In this work, I have demonstrated (i) high efficiency coupling of light into slow group velocity modes of a PCW, (ii) large bandwidth high transmission and low dispersion bends in PCWs, (iii) accurate modeling of pulse propagation in PCWs, (iv) high efficiency absorbing boundary conditions for dispersive slow group velocity modes of PCWs. To demonstrate the utility of slow light in designing high efficiency devices, I have demonstrated refractive index sensors using slow light in PCWs. In the end, a few high efficiency devices based on slow light in PCWs are mentioned. The remaining issues in the widespread use of PCW are also discussed in the last chapter.

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Coarse Wavelength Division Multiplexing (CWDM) is becoming a popular way to increase the optical throughput of fibers for short to medium haul networks at a reduced cost. The International Telecommunications Union (ITU) has defned the CWDM network to consist of eighteen channels with channel spacings of 20 nm starting at 1270 nm and ending at 1610 nm.Four and eight channel AWGs on InP, suitable for CWDM, were fabricated using a novel and versatile S-shape design. The standard horseshoe layout will not work on semiconductor for AWGs with a free spectral range (FSR) larger than 30 nm. The AWG design provides operation insensitive to thermal and polarization fluctuations, which is key for low cost operation and packaging. It will be shown thatrefractive index changes over the large operating wavelength band produced negligible effects in the transmission spectrum.Standard AWG design assumes refractive index is a constant over the operating wavelength band. As a result, the output waveguide separations are held constant on the second star coupler. As the channel number increases, secondary focal dispersion causedfrom a changing refractive index can have detrimental effects on performance. A new design method will be introduced which includes refractive index dispersion by allowing the output waveguide separations to vary. The new design is consistent with standard design but is applicable in materials with a linear index dispersion over an arbitrarily large wavelength band.Lastly, a method for increasing the transmission using multimode waveguides is discussed. Traditionally, single mode waveguides are required in order to prevent higher order waveguide modes creating ghost images in the output spectrum. Using bend loss and waveguide junction offsets, higher order modes can be filtered from the output,thereby eliminating ghost images and at the same time, increase transmission.

La realización de esta tesis doctoral permitió confirmar la combinación exitosa de la configuración de láseres guiados y las propiedades espectroscópicas de los dobles tungstatos de potasio y tierra rara para ser usados en la fabricación de dispositivos de óptica integrada. Mediante crecimiento epitaxial en fase líquida (LPE) de capas monocristalinas de KY1-x-yGdxLuy(WO4)2 activadas con Er3+ y Tm3+ se fabricaron guías de onda planas. Usando la composición KY0.58Gd0.22Lu0.17Tm0.03(WO4)2 se demostró por primera vez un láser guiado en los regímenes continuo y pulsado (Q-switch) con emisión a 1.84 m. Combinando técnicas de fotolitografía UV, Ar-ion milling y LPE, se fabricaron guías de onda acanaladas de dos tipos: superficiales y soterradas. Mediante esta novedosa combinación, se demostró por primera vez un láser guiado de Tm3+ con emisión a 1.84 m sin la necesidad de añadir espejos a la guía acanalada soterrada. / The successful combination of the advantages of the waveguide laser geometry and the spectroscopic properties of monoclinic double tungstates was confirmed in this work by the realization of planar and channel waveguide lasers activated with Tm3+. Planar waveguides activated with Er3+ and Tm3+ were fabricated by Liquid Phase Epitaxial growth (LPE) of KY1-x-yGdxLuy(WO4)2 single crystalline layers over KY (WO4)2 substrates. CW and Q-switch laser operation at 1.84 m were, for the first time, demonstrated using the lattice matched composition KY0.58Gd0.22Lu0.17Tm0.03(WO4)2 . Surface channel waveguides were fabricated by structuring the surface of the Er3+ and Tm3+-doped planar waveguides by means of standard UV-photolithography and Ar-ion milling. Buried channel waveguides were fabricated by a novel combination of LPE of the activated layers after structuring of the surface of the KY (WO4)2 substrates by Ar-ion milling. Mirrorles waveguide laser in CW regime was demonstrated using these buried channel waveguides.

Microring resonators are a fundamental building block for integrated optical filters, and have both modulation and waveform generation applications. A hybrid chalcogenide (As2S3) on titanium diffused (Ti:LiNbO3) waveguide platform has been developed to realize tunable microring resonators on a lithium niobate (LiNbO3) substrate. The use of a LiNbO3 substrate allows for electro-optic tuning, which is demonstrated for the first time on an As2S3 guided optical mode. While optical modes confined in diffused waveguides are commonly electro-optically tuned, the use of a rib waveguide external to the substrate poses new design challenges. Simulation work to determine the optimum electrode design was carried out, while also taking into account the limitations of working with a low melting temperature chalcogenide material. The tuning of this hybrid As2S3 on Ti:LiNbO3 device structure is demonstrated with fabricated Mach-Zehnder interferometers and ring resonators. Electro-optic tuning of the TM polarization utilizing the r13 LiNbO3 tuning coefficient is shown, yielding results that show an improvement over previous tunable LiNbO3 microring resonators. Simulations are also carried out to show the waveform generating capabilities of this hybrid device platform.