Multimode interference (MMI) devices operate based on the self-imaging principle. A single mode input from the input waveguide is converted to multiple modes in the interference region. By properly choosing the width and length of this section, energy distribution at the output end forms a specified ratio. Thus the MMI device is commonly used as the optical power divider in the integrated optics. The MMI devices operate at a high bandwidth and are insensitive to polarization and small variation of device dimensions. ¡@ In general, MMI manufactures use commercial simulation software to design MMI devices. However, the beam propagation method (BPM), which is the most commonly used method, assumes small angle approximation and ignores wave reflections. Other more rigorous numerical methods such as finite-difference time-domain (FD-TD) and mode matching methods consume too much computer resources and are therefore can not handle large devices like the MMIs. Therefore, we propose two novel numerical schemes to study MMI devices. The first one called full eigen-mode expansion technique (FEMET) includes all necessary modes but neglects reflection at the dielectric discontinuities. The other method considers all modes traveling in both directions is based on the coupled transverse mode integral equation (CTMIE) formulation. It is most rigorous among all methods and is capable of handling very large device structures. ¡@ In this thesis, we report the demonstration of MMI devices by efficient FEMET and rigorous CTMIE methods. Comparing the two novel studies, the CTMIE approach although highly accurate, it is much more complex and is very difficult to program. It also spends much more computer time than FEMET. On the other hand, FEMET method, being an approximate theory, produces results that are very close to that of the CTMIE results for MMI devices that are correctly designed. We found that either one of the two novel methods are able to compute quickly and accurately for adiabatic MMI devices.

In this thesis, S-bend waveguides and ring resonant filters with multimode interference (MMI) couplers have been designed and fabricated. The single-ring filters are designed to have free spectral ranges ( FSR's) of 33.3GHz, 40GHz and 50GHz. The FSR's of double-ring filters are 100GHz and 200GHz. The splitting ratios of the 9-

In this thesis, ridge waveguide laser, quantum well intermixing, 1x1 and 2x2 optical switching and ring resonator with multimode-waveguide turning mirror couplers have been investigated. We develop a new design that the perturbation is the minimum when the crossing occurs at the self-image location in a low-loss multimode waveguide. We use a center-fold low-loss multimode waveguide with a single self image at the center. Such waveguides can cross at 90 degrees or 60 degrees at the center with minimal cross talk. One can reflect the incident mode into an intersecting waveguide by introducing an idea reflecting plane. In practice, the reflector is replaced by a plane for total internal reflection with correction for Goos-Hanchen shift. Passive component for£f = 1.41 £gm samples, 1x1 60-degree multimode-waveguide turning mirror, 1x1 90-degree multimode-waveguide turning mirror, 2x2 90-degree multimode-waveguide turning mirror and a single ring resonator with 2x2 multimode-waveguide turning mirror couplers have been fabricated. (1) The multimode-waveguide turning mirror coupler with cross coupling factor (K) of 0.15 is achieved by an etched facet with a correction for Goos-Hanchen shift. (2) The length of the multimode-waveguide turning mirror coupler is only 33% of the length of conventional straight 2x2 MMI coupler with K=0.15. (3) The circumference of the curve waveguide in this ring resonator is decreased by 50%. (4) The characterization of the InP-based single ring resonator incorporating 2x2 multimode-waveguide turning mirror couplers with K= 0.15 has a free spectral range of 82 GHz, a contrast of 4 dB, and a full-width at half-maximum (FWHM) of 0.24 nm for the drop port. (5) This single resonators in In0.53Ga0.47As/In0.53Ga0.26Al0.21As grown by molecular beam epitaxy (MBE), and In0.67Ga0.33As0.6P0.4/In0.71Ga0.29As0.74P0.26 grown by metal organic chemical vapor deposition (MOCVD) have been demonstrated, respectively. We have also developed quantum well intermixing technique for the photonic integration. (1) Argon plasma bombardment followed by rapid thermal annealing for InGaAs/InGaAlAs multiple-quantum-well structures grown by MBE has been found to strongly enhance the intensity of room-temperature photoluminescence signal by more than an order of magnitude. The strength of the photoluminescence signal is found to be dependent on the plasma RF power and bombardment time. The resulting blue shift of the photoluminescence wavelength due to quantum well intermixing is found to be under 15 nm. (2) Process combining inductively-coupled-plasma reactive ion etching (ICP-RIE) and SiO2 sputtering film has been investigated for the InGaAsP and InGaAlAs multi-quantum wells (MQWs). Optimal distance is of 300 nm for InGaAsP, and of 200-nm-thick for InGaAlAs between MQWs and the upper cladding by ICP-RIE and bombardment. The process resulted in a bandgap blue-shift of 90 nm for InGaAsP, and of 60 nm for InGaAlAs. The result is very useful to regrown, the sacrificing layer and to integrate the fabrication.

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International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / Veda Systems Incorporated has recently completed the development of a completely open architecture, UNIX-based software environment for standard telemetry and more generic data acquisition applications. The new software environment operates on many state-of-the-art high-end workstations and provides a workstation independent, multiuse platform for front-end system configuration, database management, real-time graphic data display and data, logging.

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In this paper, we present the results of the design and fabrication of a 12 channel nano-membrane-based optical phased array that allows for large angle beam steering operating at wavelength=1.55µm. Our device is fabricated on silicon-on-insulator using standard CMOS process. By implementing unequally spaced waveguide array elements, we can relax the half-wavelength spacing requirement for large angle beam steering, thereby avoiding the optical coupling between adjacent waveguides and reducing the side-lobe-level of the array radiation pattern. 1D beam steering of tranverse-electric polarized single mode light is designed to be achieved thermo-optically through the use of thin film metal phase shifters. / text

L'étude concerne les lasers de puissance à semi-conducteurs émettant aux alentours de 1480nm dont l'utilisation principale est l'amplification Raman dans les fibres optiques pour les futurs systèmes de télécommunications. Cette amplification nécessite des puissances de pompe supérieures à 400mW. Les travaux ont porté sur la conception et la caractérisation des lasers de pompe en vue d'une augmentation de la puissance de sortie. Après avoir identifier les principaux effets limitant la puissance des pompes (effets thermiques, Longitudinal Spatial Hole Burning, pertes internes), trois solutions ont été mises en œuvre au cours de cette thèse pour réduire ces effets. Nous avons montré que l'introduction de guide large multimode (MMI) permettait à la fois une réduction des effets thermiques et une augmentation de la puissance de saturation de l'ordre de 10% en comparaison au laser à ruban droit. La cavité évasée a permis une réduction du Longitudinal Spatial Hole Burning entraînant un gain en puissance de saturation de l'ordre de 30% avec une puissance de 625mW pour un courant de 2.5A. Enfin, la diminution des pertes internes via l'utilisation d'un quaternaire faible indice coté InP dopé n (structure à "cladding asymétrique") a permis l'obtention d'un record de puissance (1 Watt couplé sous 5A) dans une fibre monomode avec un guide à ruban droit.

<p>Denne hovedoppgaven dreier seg omkring et konsept jeg har valgt å kalle for <i>mikronavigering</i>. Dette innebærer at jeg har sett nærmere på hvordan mobile applikasjoner, ved å utnytte informasjon som karakteriserer brukerens situasjon, kan være med på å orientere brukeren om hans omgivelser i en bygning eller et mindre område. Hensikten med dette studiet har vært å betrakte både muligheter og utfordringer tilknyttet det å nyttiggjøre forskjellige typer situasjonsbetinget informasjon (f.eks. lokasjon og kurs), eller <i>kontekst</i> for at mobile applikasjoner skal bli mer brukervennlige, fleksible og adaptive. Denne typen mobile tjenester har på mange måter et potensiale i seg til å skape en enklere og rikere menneskemaskin interaksjon. Særlig gjelder dette for de interaksjonsmiljøene som har vært i fokus i forbindelse med dette studiet, hvor omgivelser og brukerkrav skifter raskt. Samtidig har koplingen mellom mobil IT og kontekst også vært med på å skape nye utfordringer tilknyttet brukerinteraksjonen med slike verktøy.</p>