International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Current ground-based tracking systems at the DoD test and training ranges require transmission of a variety of signals from rotating platform to fixed control and process center. Implementation of commercial off the shelf (COTS) solution for transmitting high-speed, multiple-channel data signals over a rotational platform prompt the development of an advanced electro-optic hybrid rotating-to-fixed information transmission technology. Based on current demand, an Air Force-sponsored Small Business Innovative Research (SBIR) contract has been awarded to Physical Optics Corporation (POC) to modify existing tracking mounts with a unique electro-optic hybrid rotary joint (EOHRJ). The EOHRJ under current development is expected to provide the following features: 1) include a specially designed electrical slip-ring, which is able to accommodate hundreds of transmission channels, including electrical power, control, feedback, and low-speed data signals; 2) include an optical fiber slip-ring which, by incorporating with electrical time division mulitplexing (TDM) and optical wavelength division multiplexing (WDM) technologies, is able to provide multiple channel, high data rate (over gigabits per second), and bi-directional signal transmission; and 3) is designed to be reliable for harsh environmental operation, adaptive to stringent size requirement, and accommodating to existing electrical and mechanical interfaces. Besides the military use, other possible commercial applications include on board monitoring of satellite spinners, surveillance systems, instrumentation and multi spectral vision systems, emergency/medical instruments, remote sensing, and robotics.

Globally increasing levels of bandwidth and capacity requirements force the optical communications industry to produce new products that are faster, more powerful, and more efficient. In particular, optical-electronic-optical (O-E-O) conversions in Wavelength Division Multiplexing (WDM) mechanisms prevent higher data transfer speeds and create a serious bottleneck for optical communications. These O-E-O transitions are mostly encountered in the Wavelength converters of WDMs, and as a result, all-optical wavelength conversion methods have become extremely important. The main discussion in this thesis will concentrate on a specific all-optical wavelength conversion mechanism. In this mechanism, photonic crystal structures are integrated with moving MEMS/NEMS structures to create a state-of-the-art all-optical wavelength converter prototype. A wavelength conversion of 20% is achieved using this structure. Since the interaction of light with moving MEMS/NEMS structures plays an important role in the proposed wavelength conversion mechanism, modeling and simulation of electromagnetic waves becomes a very crucial step in the design process. Consequently, a subsection of this thesis will focus on a proposed enhancement to the finite-difference time-domain (FDTD) to model moving structures more efficiently and more realistically. This technique is named "Linear Dielectric Interpolation" and will be applied to more realistically and efficiently model the proposed photonic crystal MEMS/NEMS wavelength conversion mechanism.

With 400 Gbps Ethernet being developed at the time of writing this thesis, all-optical networks are a solution to the increased bandwidth requirements of data communication allowing architectures to become increasingly integrated. High density integration of optical components leads to potential ‘Optical/Photonic’ electromagnetic compatibility (EMC) and signal integrity (SI) issues due to the close proximity of optical components and waveguides. Optical EMC issues are due to backscatter, crosstalk, stray light, and substrate modes. This thesis has focused on the crosstalk in Optical Add/Drop Multiplexers (OADMs) as an EMC problem. The main research question is: “How can signal integrity be improved and crosstalk effects mitigated in small-sized OADMs in order to enhance the optical EMC in all-optical networks and contribute to the increase in integration scalability?” To answer this question, increasing the crosstalk suppression bandwidth rather than maximizing the crosstalk suppression ratio is proposed in ring resonator based OADMs. Ring resonators have a small ‘real estate’ requirement and are, therefore, potentially useful for large scale integrated optical systems. A number of approaches such as over-coupled rings, vertically-coupled rings and rings with random and periodic roughness are adopted to effectively reduce the crosstalk between 10 Gbps modulated channels in OADMs. An electromagnetic simulation-driven optimization technique is proposed and used to optimize filter performance of vertically coupled single ring OADMs. A novel approach to analyse and exploit semi-periodic sidewall roughness in silicon waveguides is proposed. Grating-assisted ring resonator design is presented and optimized to increase the crosstalk suppression bandwidth.

Abstract not available

Among various planar lightwave circuits for multiplexing/demultiplexing in an optical communication system, etched diffraction gratings (EDGs) have shown great potential due to their compactness and high spectral finesse. Conventional numerical methods for grating simulation cannot be used to simulate an EDG demultiplexer of large size (in terms of the wavelength). In the present thesis, the polarization-dependent characteristics of an EDG demultiplexer are analyzed with a boundary element method (BEM) for both an echelle grating coated with a metal and a dielectric grating with total internal reflection (TIR) facets. For EDGs with metal-coated facets, we use a more effective method, namely, method of moments (MoM). Futhermore, a fast simulation method for EDGs with TIR facets is presented based on the Kirchhoff–Huygens principle and the Goos-Hänchen shift. This simple method has a good agreement with a BEM over a wide range of practical parameters of the device. Several novel designs are presented in order to improve the performances of EDGs. (1) By making some appropriate roughness on the surface of the shaded facets, the PDL of the demultiplexer can be effectively reduced over a large bandwith. (2) For EDGs based on Si nanowire structures, we compensate the polarization-dependent wavelength dispersion (PDλ) in the whole operational spectrum by introducing a polarization compensation area in its free propagation region. (3) An EDG demultiplexer with suppressed sidelobe is designed. The designed EDG demultiplexer can give a crosstalk as small as 50 dB in theory. (4) By chirping the diffraction order for each facet, we minimize the envelope intensity for the other adjacent diffraction orders to achieve a negligible return loss in a large spectral width. (5) A design for EDG demultiplexers is presented to obtain both large grating facets and a larger free spectral range (FSR) using the optimal chirped diffraction orders for different facets. The influences of the fabrication errors (e.g., rounded effect, surface roughness and point defect in the waveguide) on the performance (such as the insertion loss, the polarization dependent loss and the chromatic dispersion) of an EDG demultiplexer are also analyzed in detail. Silicon nanowire waveguides and related EDGs are studied. An EDG demultiplexer with 10 nm spacing is finally fabricated and characterized. / QC 20100910

This thesis puts focus on the technological challenges for Wavelength Division Multiplexed Passive Optical Network (WDM-PON) implementation, and presents novel semiconductor optical devices for deployment at the optical network unit (ONU). The first-ever reported L-band Reflective semiconductor optical amplifier (RSOA) is presented based on InP-base material. A theoretical model is developed to estimate the optical gain and the saturation power of this device compared to a conventional SOA. Experiments on this device design show long-range telecom wavelength operation, with polarization-independent gain of greater than 20 dB, and low saturation output power of 0 dBm suitable for PON applications. Next, the effect of the amplified spontaneous emission noise of RSOA devices on WDM-PON system is investigated. It is shown through theoretical modeling and simulations that the RSOA noise combined with receiver noise statistics increase probability of error, and induce considerable power penalties to the WDM-PON system. By improving the coupling efficiencies, and by distributing more current flow to the input of these devices, steps can be taken to improve device noise characteristics. Further, in spectrally-spliced WDM-PONs deploying RSOAs, the effect of AWG filter shape on system performance is investigated. Simulation modeling and experiments show that deployment of Flat-band AWGs is critical for reducing the probability of error caused by AWG spectral shape filtering. Flat-band athermal AWGs in comparison to Gaussin-shape counterparts satisfy the maximum acceptable error probability requirements, and reduce the power penalty associated with filtering effect. In addition, detuning between two AWG center wavelengths impose further power penalties to the WDM-PON system. In the last section of this thesis, motivated by RSOA device system limitations, a novel injection-locked Fabry-Perot (IL-FP) device is presented which consists of a gain section monolithically integrated with a phase section. The gain section provides locking of one FP mode to a seed source wavelength, while the phase modulator allows for adjusting the wavelength of the internal modes by tuning bias current to maintain mode-locking. This device counters any mode drifts caused by temperature variations, and allows for cooler-less operation over a wide range of currents. The devices and the performance metrics subsequently allow for a hybrid integration platform on a silicon substrate and integrate many functionalities like reflective modulator with thin film dielectric filter and receiver on a single chip for deployment at the user-end of future-proof low cost WDM-PONs.

This thesis puts focus on the technological challenges for Wavelength Division Multiplexed Passive Optical Network (WDM-PON) implementation, and presents novel semiconductor optical devices for deployment at the optical network unit (ONU). The first-ever reported L-band Reflective semiconductor optical amplifier (RSOA) is presented based on InP-base material. A theoretical model is developed to estimate the optical gain and the saturation power of this device compared to a conventional SOA. Experiments on this device design show long-range telecom wavelength operation, with polarization-independent gain of greater than 20 dB, and low saturation output power of 0 dBm suitable for PON applications. Next, the effect of the amplified spontaneous emission noise of RSOA devices on WDM-PON system is investigated. It is shown through theoretical modeling and simulations that the RSOA noise combined with receiver noise statistics increase probability of error, and induce considerable power penalties to the WDM-PON system. By improving the coupling efficiencies, and by distributing more current flow to the input of these devices, steps can be taken to improve device noise characteristics. Further, in spectrally-spliced WDM-PONs deploying RSOAs, the effect of AWG filter shape on system performance is investigated. Simulation modeling and experiments show that deployment of Flat-band AWGs is critical for reducing the probability of error caused by AWG spectral shape filtering. Flat-band athermal AWGs in comparison to Gaussin-shape counterparts satisfy the maximum acceptable error probability requirements, and reduce the power penalty associated with filtering effect. In addition, detuning between two AWG center wavelengths impose further power penalties to the WDM-PON system. In the last section of this thesis, motivated by RSOA device system limitations, a novel injection-locked Fabry-Perot (IL-FP) device is presented which consists of a gain section monolithically integrated with a phase section. The gain section provides locking of one FP mode to a seed source wavelength, while the phase modulator allows for adjusting the wavelength of the internal modes by tuning bias current to maintain mode-locking. This device counters any mode drifts caused by temperature variations, and allows for cooler-less operation over a wide range of currents. The devices and the performance metrics subsequently allow for a hybrid integration platform on a silicon substrate and integrate many functionalities like reflective modulator with thin film dielectric filter and receiver on a single chip for deployment at the user-end of future-proof low cost WDM-PONs.

Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2004. / "A dissertation in engineering and computer networking." Advisor: Ghulam Chaudhry. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 22, 2006. Includes bibliographical references (leaves 135-157). Online version of the print edition.

This master´s thesis explores a comparison of the transmission parameters in time division networks and wavelength division networks. The paper is divided into the three sections. The first part deals with preparation of individual standards time division networks and specific wavelength division networks, along with passive components used passive optical networks. The second part briefly describes the possibility of transmission of television signals in optical networks and the last part is devoted to simulating networks GPON and WDM-PON and comparison simulated values.

The wavelength-division-multiplexed passive optical network (WDM-PON) offers many advantages such as large bandwidth per user, easy management, high network security and low insertion loss enabling long-reach and/or high split-ratio. However, with the rapid development and growing interest for deployment of WDM-PON, the PON systems are becoming increasingly vulnerable to various failures. Therefore, network supervision becomes extremely important to guarantee an appropriate level of network reliability performance. The aim of PON supervision is to provide automated test and diagnostic capability without compromising the available bandwidth for services. An essential function is to detect any kind of deterioration in the network that can cause suspended services and to remotely localize these faults in order to avoid the high cost arising from troubleshooting. In this thesis, we evaluate several existing WDM PON supervision methods, based on which two simple and cost-effective new solutions are proposed to localize fiber failures in WDM PON systems. In the first solution, a conventional optical time domain reflectometry (OTDR) and a switch unit are employed, while in the second method, a novel architecture based on N×N arrayed waveguide grating (AWG) is proposed. Both methods are able to localize failures in feeder fiber and drop fibers without e.g. using expensive tunable OTDRs. A patent has been filed based on the second solution. The first proposed method is validated by simulations using VPI Transmission Maker. According to the results, this supervision method is able to give accurate measurement of many different types of failures that may happen in a fiber link. Furthermore, VPI is examined in terms of its future applicability in modeling complete PON supervision methods based on OTDR.