Following the intensive development of isolated (i.e., not coupled with on-chip waveguide) vertically rolled-up microtube ring resonators (VRU-MRRs) for both active and passive applications, a variety of microtube-based devices has been realized. These include microcavity lasers, optical sensors, directional couplers, and active elements in lab-on-a-chip devices. To provide more advanced and complex functionality, the focus of tubular geometry research is now shifting toward (i) refined vertical light transfer in 3D stacks of multiple photonic layers and (ii) to make microfluidic cooling system in the integrated optoelectronic system. Based on this motivation, this PhD research is devoted to the demonstration and the implementation of monolithic integration of VRU-MRRs with photonic waveguides for 3D photonic integration and their optofluidic applications. Prior to integration, high-quality isolated VRU-MRRs on the flat Si substrate are firstly fabricated by the controlled release of differentially strained titanium-dioxide (TiO2) bilayered nanomembranes. The fabricated microtubes support resonance modes for both telecom and visible photonics. The outcome of the isolated VRU-MRRs is a record high Q (≈3.8×10^3) in the telecom wavelength range with optimum tapered optical fiber resonator interaction. To further study the optical modes in the visible and near infrared spectral range, μPL spectroscopy is performed on the isolated VRU-MRRs, which are activated by entrapping various sizes of luminescent nanoparticles (NPs) within the windings of rolled-up nanomembranes based on a flexible, robust and economical method. Moreover, it is realized for the first time, in addition to serving as light sources that NPs-aggregated in isolated VRU-MRRs can produce an optical potential well that can be used to trap optical resonant modes. After achieving all the required parameters for creating a high-quality TiO2 VRU-MRR, the monolithic integration of VRU-MRRs with Si nanophotonic waveguides is experimentally demonstrated, exhibiting a significant step toward 3D photonic integration. The on-chip integration is realized by rolling up 2D pre-strained TiO2 nanomembranes into 3D VRU-MRRs on a microchip which seamlessly expanded over several integrated waveguides. In this intriguing vertical transmission configuration, resonant filtering of optical signals at telecom wavelengths is demonstrated based on ultra-smooth and subwavelength thick-walled VRU-MRRs. Finally, to illustrate the usefulness of the fully integrated VRU-MRRs with photonic waveguides, optofluidic functionalities of the integrated system is investigated. In this work, two methods are performed to explore optofluidic applications of the integrated system. First, the hollow core of an integrated VRU-MRR is uniquely filled with a liquid solution (purified water) by setting one end of the VRU-MRRs in contact with a droplet placed onto the photonic chip via a glass capillary. Second, the outside of an integrated VRU-MRR is fully covered with a big droplet of liquid. Both techniques lead to a significant shift in the WGMs (Δλ≈46 nm). A maximum sensitivity of 140 nm/refractive index unit, is achieved. The achievements of this PhD research open up fascinating opportunities for the realization of massively parallel optofluidic microsystems with more functionality and flexibility for analysis of biomaterials in lab-on-a-tube systems on single chips. It also demonstrates 3D photonic integration in which optical interconnects between multiple photonic layers are required.

The work provides an overview of different integrated optical amplifiers. Semiconductor optical amplifiers and fiber amplifiers are described, as well as devices that utilize non-linear effects, nanocrystalline materials, or photonic crystals. Dielectric materials that are doped with rare-earth ions are considered more thoroughly. After a review of the principles of their optical activity the general mechanisms of excitation and emission are described. Materials aspects regarding the spectral range, their fabrication and the solubility of the dopants follow. An erbium-doped alumina waveguide amplifier, reported earlier in the literature, is chosen as an example to demonstrate the feasibility of such components. A theoretical model of the population densities of the energy levels is derived for the simulation. By numerical methods the non-linear system of the rate equations is solved and the stability of the steady state is shown. The simulation of the amplifier demonstrates the dependence of the gain of both the excitation energy and the z-coordinate. Moreover, the superiority of an excitation wavelength of 980 nm compared to 1530 nm is shown. With the model the literature data could be reproduced. / Die Arbeit gibt einen Überblick über verschiedene Möglichkeiten der Realisierung integriert-optischer Wellenleiterverstärker. Ausgehend von optischen Halbleiter- und Faserverstärkern werden einführend ebenso Anordnungen beschrieben, die nichtlineare Effekte sowie nanokristalline Materialien und photonische Kristalle nutzen. Besondere Bedeutung kommt dielektrischen Materialien zu, die mit optisch aktiven Dotanden, bevorzugt Seltenerdionen, versehen sind. Hierbei werden die Ursachen für die optische Aktivität der Lanthanide sowie die generellen Mechanismen der Anregungs- und Emissionsprozesse beschrieben. Aspekte der Materialauswahl, vor allem hinsichtlich des verwendeten Spektralbereiches sowie bezüglich ihrer Herstellung und der Löslichkeit der Dotanden schließen sich an. Anhand eines Literaturbeispiels wird die Realisierbarkeit eines erbiumdotierten Aluminiumoxid-Wellenleiterverstärkers demonstriert. Hierfür wird ein Modell zur Simulation der Besetzungsdichten der angeregten Energieniveaus abgeleitet und mittels numerischer Methoden das sich ergebende, nichtlineare System der Ratengleichungen gelöst, wobei besonders die Stabilität des stationären Besetzungszustandes herausgearbeitet wird. Die Simulation der Verstärkeranordnung zeigt zum einen die Abhängigkeit der Verstärkung von der z-Koordinate sowie der Pumpleistung; zum anderen wird deutlich, dass die Anregung bei 980 nm der Variante bei 1530 nm überlegen ist. Mit dem verwendeten Modell konnten die Literaturdaten reproduziert werden.

In Medizin und Technik besteht ein Bedarf an flexiblen, miniaturisierten Dosisleistungs-messgeräten mit hoher Ortsauflösung für den Einsatz in Strahlungsfeldern hoher Dosisleistung und Dosisleistungsgradienten. Lichtwellenleiterbasierte Dosisleistungsmess-systeme können diese Anforderungen erfüllen. Sie bestehen aus einem strahlungssensitiven Leuchtstoff, welcher über einen flexiblen Lichtleiter an einen Lichtdetektor gekoppelt ist. Die Eliminierung des dominierenden Störeinflusses, des bei Bestrahlung des Lichtleiters generierten Stem-Effekts, ist eine inhärente Herausforderung aller lichtwellenleiter¬basierten Dosisleistungsmesssysteme. In der vorliegenden Arbeit wird ein solches System unter Verwendung der Lumineszenz der gewebeäquivalenten Detektormaterialien Berylliumoxid und Lithiumtetraborat realisiert. Der Schwerpunkt liegt dabei auf der Untersuchung von Methoden der Stem-Eliminierung unter Nutzung der zeitlichen Charakteristik der Lumineszenzmaterialien sowie der zeitlichen Struktur des Strahlungsfeldes oder einer modulierten optischen Stimulation. Eine performante Ausleseelektronik auf FPGA-Basis ermöglicht Echtzeit-Messungen mit einer Abtastung von 10 ns. Verschiedene Auswertemethoden generieren aus den Rohdaten in Zeitstempelform eine stem-unabhängige, dosisleistungsproportionale Detektorantwort. / In medicine and technology there is a demand for flexible, miniaturized dose rate measurement systems with high spatial resolution for the application in radiation fields of high dose rates and dose rate gradients. Fiber optic coupled dosimeters can meet these requirements. They consist of a radiation sensitive luminescent material which is connected to a light detector with a flexible light guide. The elimination of the dominant perturbation, which is the stem effect generated by irradiation of the light guide, is one inherent challenge of all fiber optic dosimeters. In the present work such a system is realized, using the luminescence of the two tissue equivalent detector materials beryllium oxide and lithium tetraborate. The main focus is on the investigation of methods of stem elimination, exploiting the temporal characteristics of the luminescent materials, as well as the time structure of the irradiation or a modulated optical stimulation. For this purpose, capable FPGA-based read out electronics are employed, which enable real time measurements with 10 ns sampling. Different methods of analysis process the time stamp raw data and generate a stem-free, dose rate proportional detector response.

This paper demonstrates an approach for passive alignment and assembly of link components for board-level very-short range optical interconnects. This interchip optical link is based on planar polymeric multimode waveguides and glassbased electro-optical transceivers. The main aim of the work is the investigation of assembly processes of link components in order to fulfill the tolerance requirements using passive alignment. The optical characterization in regard to the optical coupling between link components will define the tolerances for the alignment process. This optical analysis is based on measurements of spatial coupling characteristics. The influence of assembly tolerances on the coupling efficiency is investigated. Flip-chip assembly of electro-optical devices on the glass interposer and of the glass interposer on optical overlay is presented to prove the implementation of the concept.

This paper discusses the technology development for integration of parallel optical interconnects on board-level, including the active and passive optical components as well as the electrical integrated circuitry. The inter-chip link is based on planar polymeric optical multimode waveguides with integrated out-of-plane coupling optics and optical transceiver subassemblies based on glass interposer. Integration of polymeric waveguides on flexible substrates will be shown since the realization of an overlay optical substrate enhances the yield and testability of the final hybrid electrooptical printed circuit board (EOPCB). Realized on-board waveguides feature low insertion loss (minimum attenuation coefficient of below 0.1 dB/cm). For short planar waveguides (Lwaveguide = 9 cm) error free transmission (BER < 10-12) up to 30 Gbit/s was achieved. The development of glass interposer passive optical coupling structures for VCSEL-based short-distance links will be described.