Inorganic material based electronics and photonics on unconventional substrates have shown tremendous unprecedented applications, especially in areas that traditional wafer based electronics and photonics are unable to cover. These areas range from flexible and conformal consumer products to biocompatible medical devices. This thesis presents the research on single crystal silicon nanomembrane photonics on different substrates, especially flexible substrates. A transfer method has been developed to transfer silicon nanomembrane defect-freely onto glass and flexible polyimide substrates. Using this method, intricate single crystal silicon nanomembrane device, such as photonic crystal microcavity, has been transferred onto flexible substrates. To test the device, subwavelength grating couplers are designed and implemented to couple light in and out of the transferred waveguides with high coupling efficiency. The cavity shows a quality factor ~ 9000 with water cladding and ~30000 with glycerol cladding, which is comparable to the same cavity demonstrated on silicon-on-insulator platform, indicating the high quality of the transferred silicon nanomembrane. The device could be bended to a radius less than 15 mm. The experiments show that the resonant wavelength shifts to longer wavelength under tensile stress, while it shifts to shorter wavelength under compressive stress. The sensitivity of the cavity is ~70 nm/RIU, which is independent of bending radius. This demonstration opens vast possibilities for a whole new range of high performance, light-weight and conformal silicon photonic devices. The techniques and devices (e.g. wafer bonding, stamp printing, subwavelength grating couplers, and modulator) generated in the research can also be beneficial for other research fields. / text

The demand for higher bandwidth and higher speed driven by semiconductor technology development draws a great deal of research efforts devoted to the development of high speed data communication. Challenges on electrical copper interconnects at high frequency make optical interconnect technologies become a promising alternative to conventional electrical interconnects at different levels. This doctoral dissertation describes polymer based nano- and micro-photonic devices for three-dimensional optical interconnects. Two areas are focused, (1) polymer based two-dimensional (2D) and three-dimensional (3D) photonic crystal fabrication and simulation for laser beam steering applications, (2) polymer based optical waveguide array and shared bus waveguide with embedded 45° micro-mirrors for board level optical interconnects. A three-dimensional (3D) face-centered cubic (FCC) type polymer based photonic crystal using the polymer material SU-8 was simulated and successfully fabricated using a polygonal prism based holographic fabrication method. The theoretical study of polymer based photonic crystals was carried out for laser beam steering, which is based on the superprism effect. Horizontally stacked two-dimensional (2D) photonic crystal was fabricated by a double exposure holographic interference method. The k-vector superprism effect, the principle for beam steering, was studied in detail through EFC (Equi-frequency Contour) analysis. A polymer based optical waveguide array with embedded 45° micro-mirrors for board level optical interconnects was prepared using a Ni metal hard mold by a UV imprint technique. A nickel based metal mold with 45º tilted surfaces on both ends of the channel waveguide was prepared through the electroplating process. To obtain a precise 45º tilted angle, a 50µm thick SU-8 layer was exposed under de-ionized water. High speed optical testing (10Gb/s) was carried out on the polymeric optical waveguide array with embedded 45º micro-mirrors on flexible substrate for out-of-plane optical interconnects. A polymer based 3-to-3 shared optical bus waveguide with opposite 45º micro-mirrors was designed and fabricated using the metallic hard mold method. The Ni metal hard mold was successfully prepared using the Ni electroplating method. This metallic hard mold provides a convenient way to fabricate the polymeric optical bus waveguide devices through the imprint technique. / text

Optoelectronic devices operating in the mid-infrared spectral region are attracting increasing attention due to potential applications in a wide range of disciplines. For example, mid-infrared photodetectors play a key role in thermophotovoltaic (TPV) energy conversion, whereby a photovoltaic device is used to extract electrical power from heat radiation. This technology is attractive for waste heat harvesting and clean energy production in several different environments. Similarly, mid-infrared light sources are particularly useful for biochemical sensing and spectroscopy, where the distinctive absorption features of many molecular species of interest can be exploited for their sensitive identification and detection. Both devices are investigated in this thesis work. In the area of TPV energy conversion, I have studied the use of intersubband transitions in semiconductor quantum cascade structures as a means to overcome the fundamental limitations of existing TPV devices using mature InP-based technology. Very efficient coverage of the incident radiation spectrum and optimal current matching can be achieved using multiple quantum-cascade structures monolithically integrated with a p-n junction, by taking advantage of their intrinsic cascading scheme, spectral agility, and design flexibility. Numerical simulations indicate that this approach can effectively double the present state-of-the-art in TPV output electrical power. In the area of mid-infrared light sources, my work has focused on developing efficient light emitters based on tensilely strained Germanium nanomembranes (Ge NMs). These ultrathin (a few ten nanometers) single-crystal membranes are good candidates for the development of CMOS-compatible Group-IV light sources, by virtue of their ability to sustain large strain levels and in the process become direct-bandgap materials. My research efforts have concentrated on the development of optical cavities based on Ge NMs that can satisfy the mechanical flexibility requirement of this materials platform. In particular, photonic-crystal (PhC) cavities in the form of disconnected dielectric-column arrays have been designed and fabricated based on a novel membrane assembly method, producing clear cavity-mode features in NM photoluminescence spectra. / 2016-08-17T00:00:00Z

Photonic bandgap structures have provided promising platform for miniaturization of modern integrated optical devices. In this thesis, a photonic crystal based ring resonator (PCRR) is proposed and optimized to exhibit high quality factor. Also, force sensing application of the optimized PC ring resonator and Dense Wavelength Division Multiplexing (DWDM) application of the PCRR are discussed. Finally fabrication and characterization of the PCRR is presented. A photonic crystal ring resonator is designed in a hexagonal lattice of air holes on a silicon slab. A novel approach is used to optimize PCRR to achieve high quality factor. The numerical analysis of the optimized photonic crystal ring resonator is presented in detail. For all electromagnetic computations Finite Difference Time Domain (FDTD) method is used. The improvement in Q factor is explained by using the physical phenomenon, multipole cancellation of the radiation held of the PCRR cavity. The corresponding mathematical frame work has been included. The forced cancellation of lower order radiation components are verified by plotting far held radiation pattern of the PCRR cavity. Then, the force sensing application of the optimized PCRR is presented. A high sensitive force sensor based on photonic crystal ring resonator integrated with silicon micro cantilever is presented. The design and modelling of the device, including the mechanics of the cantilever, FEM (Finite Element Method) analysis of the cantilever beam with PC and without PC integrated on it. The force sensing characteristics are presented for forces in the range of 0 to 1 N. For forces which are in the range of few tens of N, a force sensor with bilayer cantilever is considered. PC ring resonator on the bilayer of 220nm thick silicon and 600nm thick SiO2 plays the role of sensing element. Force sensing characteristics of the bilayer cantilever for forces in the range of 0 to 10 N are presented. Fabrication and characterization of PCRR is also carried out. This experimental work is done mainly to understand practical issues in study of photonic crystal ring resonators. It is proved that Q factor of PCRR can be signi cantly improved by varying the PCRR parameters by the proposed method. Dense Wavelength Division Multiplexing (DWDM) application of PC ring resonator is included. A novel 4-channel PC based demultiplexer is proposed and optimized in order to tolerate the fabrication errors and exhibit optimal cross talk, coupling efficiency between resonator and various channels of the device. Since the intention of this design is, to achieve the device performance that is independent of the unavoidable fabrication errors, the tolerance studies are made on the performance of the device towards the fabrication errors in the dimension of various related parameters. In conclusion we summarize major results, applications including computations and practical measurements of this work and suggest future work that may be carried out later.

The emergence of optical applications, such as lasers, fiber optics, and semiconductor based sources and detectors, has created a drive for smaller and more specialized devices. Nanophotonics is an emerging field of study that encompasses the disciplines of physics, engineering, chemistry, biology, applied sciences and biomedical technology. In particular, nanophotonics explores optical processes on a nanoscale. This dissertation presents nanophotonic applications that incorporate various forms of the organic polymer N-isopropylacrylamide (NIPA) with inorganic semiconductors. This includes the material characterization of NIPA, with such techniques as ellipsometry and dynamic light scattering. Two devices were constructed incorporating the NIPA hydrogel with semiconductors. The first device comprises a PNIPAM-CdTe hybrid material. The PNIPAM is a means for the control of distances between CdTe quantum dots encapsulated within the hydrogel. Controlling the distance between the quantum dots allows for the control of resonant energy transfer between neighboring quantum dots. Whereby, providing a means for controlling the temperature dependent red-shifts in photoluminescent peaks and FWHM. Further, enhancement of photoluminescent due to increased scattering in the medium is shown as a function of temperature. The second device incorporates NIPA into a 2D photonic crystal patterned on GaAs. The refractive index change of the NIPA hydrogel as it undergoes its phase change creates a controllable mechanism for adjusting the transmittance of light frequencies through a linear defect in a photonic crystal. The NIPA infiltrated photonic crystal shows greater shifts in the bandwidth per ºC than any liquid crystal methods. This dissertation demonstrates the versatile uses of hydrogel, as a means of control in nanophotonic devices, and will likely lead to development of other hybrid applications. The development of smaller light based applications will facilitate the need to augment the devices with control mechanism and will play an increasing important role in the future.

Le contrôle des rejets dans l'atmosphère est une préoccupation importante de nos sociétés. Ce travail de thèse s'inscrit dans ce cadre en proposant l'étude et la réalisation de composants lasers compatibles avec des systèmes de détection de gaz polluants. La spectroscopie d'absorption par diodes laser accordables est une méthode de détection de gaz, très sensible et sélective. Elle nécessite des diodes laser fonctionnant en régime continu, à température ambiante avec une émission monofréquence et une large accordabilité. Pour répondre à ces exigences, nous proposons une géométrie originale où deux cavités laser sont couplées par un miroir à cristal photonique (CP). Le domaine du moyen infrarouge (2 à 5 µm), où de nombreuses espèces gazeuses présentent de fortes raies d'absorption, est particulièrement intéressant pour ces applications. Pour atteindre cette gamme, la famille des matériaux à base d'antimoniures est la mieux adaptée car elle permet l'obtention de composants émettant au-delà de 2 µm. Deux géométries ont été étudiées, l'une avec les CPs placés de part et d'autre du ridge, l'autre avec les CPs le traversant. Les modélisations ont montré que le second design était le plus efficace. Un enjeu majeur de cette thèse a été le développement d'un procédé technologique complet qui fait appel à des étapes de photolithographie associées à des étapes d'insolation électronique pour la définition des CPs et l'ouverture de l'isolant. Il a nécessité la mise au point de la gravure profonde des CPs. Les caractérisations des structures ont montré un fonctionnement en continu, à température ambiante. Une émission monofréquence a été obtenue. Des mesures d'absorption de méthane et de monoxyde de carbone ont validé la faisabilité de l'utilisation de ces structures dans un système de détection de gaz. / Mitigation of atmospheric emissions is an important concern for today's society. This PhD work is in keeping with this pattern by proposing to study and realize laser devices to be integrated in systems for detecting polluting gases. Tunable diode laser absorption spectroscopy is a technique for gas detection which is very sensitive and selective. It makes use of laser diodes operating in the continuous wave regime at room temperature with a single frequency emission and a large tuning range. For fulfilling these requirements, we propose an innovative design where two laser cavities are coupled by a photonic crystal mirror (PC). The mid-infrared range (2 to 5 µm), where numerous gas species have strong absorption lines, is of particular interest for these applications. The antimonide system is the best suited for reaching this wavelength range because it allows to make devices emitting beyond 2 µm.Two designs have been studied, one with PCs placed on both sides of the ridge, the other one with PCs going through the ridge. Modelling has shown that the second design is the most efficient. A major challenge in this work was to develop a complete technological process making use of photolithography steps combined with electronic insulation steps for defining the PCs and opening the insulator layer. A special care has been devoted to perfecting deep etching of the PCs. Subsequent characterizations showed that the devices work in the continuous wave regime at room temperature. Single frequency emission was obtained. Absorption measurements with methane and carbon monoxide have validated the use of these devices in a system for gas detection.

Au cours des dernières années, la recherche dans le domaine des bio-capteurs optiques sans marquage a connu une croissance rapide du fait de la nécessité de développer des méthodes toujours plus performantes pour la détection et la mesure de faibles concentrations de molécules spécifiques dans divers domaines. Parmi les différentes méthodes optiques existantes, les cristaux photoniques (CP) offrent une alternative prometteuse du fait de leur sensibilité. D’autre part, le diamant, utilisé comme matériau pour la réalisation de ces dispositifs offre de bonnes propriétés optiques et la possibilité de réaliser une fonctionnalisation de surface efficace facilement. Dans ce contexte, cette thèse propose un nouveau design de bio-capteur optique à cristaux photonique bi-dimensionnel en diamant, fonctionnant à des longueurs d'onde proche de 800 nm.Une géométrie originale de trous d'air circulaires organisés selon une maille carrée a été choisie pour maximiser la sensibilité du bio-capteur à des changements d'indice de réfraction en leur surface. Il a été démontré analytiquement que les modes à faible vitesse de groupe avaient une plus grande sensibilité à ces changements. Des méthodes numériques ont permis de préciser les paramètres géométriques optimaux du CP. Le design proposé est basé sur la mesure de décalage angulaire dans le spectre en réflexion d'un mode lent résonant du CP quand celui-ci est éclairé par une lumière monochromatique.Des films de diamant polycristallin de quelques centaines de nanomètres à quelques micromètres d’épaisseur ont été déposés sur différents substrats. L’ensemble des procédés technologiques nécessaires à la réalisation des CP et spécifiques aux films de diamant polycristallin ont été développés ou optimisés, comme, entre autre, un procédé de lissage obtenu par gravure plasma, un procédé de transfert de films de diamant sur un autre substrat par collage, un procédé d’amincissement des films de diamant et la fabrication des CP par lithographie électronique et gravure plasma.Les échantillons réalisés dans la salle blanche du C2N ont été mesurés optiquement et les hypothèses théoriques concernant les performances du capteur ont étés validées. Un mode avec une vitesse de groupe c/100 à une longueur d'onde de 800 nm a été mesuré et la sensibilité correspondant a cette structure a été estimée à 500 degrés par unité d'indice de réfraction (°/RIU), une valeur supérieure d’un ordre de grandeur à celles rencontrées couramment dans les capteurs à CP bidimensionnels. Ces résultats représentent un premier pas vers un biocapteur hautement sensible, comprenant une fonctionnalisation de surface du diamant pour une reconnaissance de cible spécifique. / Over the last years, the research on the label-free biosensor topic has experienced a very rapid growth because of the need to develop high-performing methods to detect and measure low concentrations of specific molecules in various fields. Among all the methods proposed, photonic crystals (PhC) structures offers a good alternative due to their sensitivity. Moreover, the use of diamond as material make the proposed device more attractive due to its optical properties, high chemical stability and efficiency of surface functionalization. In this context, this PhD thesis propose a new design of optical bio-sensor based on diamond two-dimensional photonic crystals, working at the wavelength near 800 nm.An original geometry of circular air holes arranged in squared lattice was chosen in order to maximize the sensitivity of such photonic structures to refractive index changes on their surface. It was analytically proven that modes with low group velocity are more sensitive to these variations. Numerical methods gave the necessary information to determine the optimal geometrical parameters of the PhC. The proposed design is based on measuring the shift of the angular reflectivity of a low group velocity guided mode resonance (GMR) PhC when probed with a single frequency light.Polycrystalline diamond films were grown on two different substrates, with thicknesses ranging from a few hundreds of nanometers to several micrometers. The technological processes required for the realization of PhC on polycrustalline diamond were developed or optimized, such as surface planarization by inductively coupled plasma (ICP) dry etching, diamond film transfer onto new substrate by wafer bonding process, diamond films thinning and surface patterning with PhC using Electronic Beam Lithography (EBL) and ICP methods.The samples realized in clean-room facilities were optically measured and the theoretical assumptions were validated. A GMR with a c/100 group velocity at a wavelength of 800 nm was measured and its sensitivity is estimated to be in the order of 500 degrees/ refractive index unit (°/RIU), a value that is one order of magnitude higher than the typical values encountered for sensors based on 2D PhC. These results represents a first step towards a highly sensitive bio-sensor, including a diamond surface functionalization for specific target recognition.

A theoretical investigation of one-dimensional planar photonic crystal waveguides is carried out. These waveguides consist of a dielectric layer sandwiched between two semiinfinite periodic dielectric structures. Using a novel approach, exact analytical solutions for guided modes in such waveguides are presented. The se rigorous solutions allow one to distinguish clearly between the index-guiding regime and guidance due to the photonic crystal effect. In the first part of this investigation, a rigorous analysis of the reflection of uniform plane waves from a semi- infinite periodic dielectric structure is undertaken. Both parallel and perpendicular polarizations for the incident plane wave are considered. Exact expressions for the reflection coefficients corresponding to two polarization cases are obtained using an impedance approach. The results for the reflection coefficient are then used to study propagation properties of guided modes in one-dimensional photonic crystal waveguides with semiinfinite periodic cladding regions. Characteristic equations, from which propagation constants of guided modes can be obtained, and solutions for electromagnetic fields of these modes are derived. Solutions for both TE (transverse electric) and TM (transverse magnetic) modes are presented. Numerical results for the propagation constant and field distributions of several lower-order modes are presented. The solutions unique to photonic crystal waveguides are emphasized. / Master of Science

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In this dissertation, liquid crystal materials and devices are investigated in meeting the challenges for photonics and communications applications. The first part deals with polymer-stabilized liquid crystal (PSLC) materials and devices. Three polymer-stabilized liquid crystal systems are developed for optical communications. The second part reports the experimental investigation of a novel liquid-crystal-infiltrated photonic crystal fiber (PCF) and explores its applications in fiber-optic communications. The curing temperature is found to have significant effects on the PSLC performance. The electro-optic properties of nematic polymer network liquid crystal (PNLC) at different curing temperatures are investigated experimentally. At high curing temperature, a high contrast, low drive voltage, and small hysteresis PNLC is obtained as a result of the formed large LC micro-domains. With the help of curing temperature effect, it is able to develop PNLC based optical devices with highly desirable performances for optical communications. Such high performance is generally considered difficult to realize for a PNLC. In fact, the poor performance of PNLC, especially at long wavelengths, has hindered it from practical applications for optical communications for a long time. Therefore, the optimal curing temperature effect discovered in this thesis would enable PSLCs for practical industrial applications. Further more, high birefringence LCs play an important role for near infrared photonic devices. The isothiocyanato tolane liquid crystals exhibit a high birefringence and low viscosity. The high birefringence LC dramatically improves the PSLC contrast ratio while keeping a low drive voltage and fast response time. A free-space optical device by PNLC is experimentally demonstrated and its properties characterized. Most LC devices are polarization sensitive. To overcome this drawback, we have investigated the polymer-stabilized cholesteric LC (PSCLC). Combining the curing temperature effect and high birefringence LC, a polarization independent fiber-optical device is realized with over 30 dB attenuation, ~12 Vrms drive voltage and 11/28 milliseconds (rise/decay) response times. A polymer-stabilized twisted nematic LC (PS TNLC) is also proposed as a variable optical attenuator for optical communications. By using the polarization control system, the device is polarization independent. The polymer network in a PS TNLC not only results in a fast response time (0.9/9 milliseconds for rise/decay respectively), but also removes the backflow effect of TNLC which occurs in the high voltage regime.