Nonlinear effects with a focus on cross phase modulation and its impact on wavelength division multiplexing optical fibre networks

The demand for faster data transmission is ever increasing. Wavelength division multiplexing (WDM) presents as a viable solution to increase the data transmission rate significantly. WDM systems are based on the ability to transmit multiple wavelengths simultaneously down the fibre. Unlike time division multiplexing (TDM) systems, WDM systems do not increase the data transfer by increasing the transmission rate of a single channel. In WDM systems the data rate per channel remains the same, only multiple channels carry data across the link. Dense wavelength division multiplexing (DWDM) promises even more wavelengths packed together in the same fibre. This multiplication of channels increases the bandwidth capacity rapidly. Networks are looking into making use of technology that will ensure no electronic signal regeneration at any point within the DWDM network. Examples are; reconfigurable optical add/drop multiplexers (ROADM) and optical cross connect (OXC) units. These components essentially enable network operators to split, combine and multiplex optical signals carried by optical fibre. WDM allows network operators to increase the capacity of existing networks without expensive re-cabling. This provides networks with the flexibility to be upgraded to larger bandwidths and for reconfiguration of network services. Further, WDM technology opens up an opportunity of marketing flexibility to network operators, where operators not only have the option to rent out cables and fibres but wavelengths as well. Cross phase modulation (XPM) poses a problem to WDM networks. The refractive index experienced by a neighbouring optical signal, not only depends on the signal’s intensity but on the intensity of the co-propagating signal as well. This effect leads to a phase change and is known as XPM. This work investigates the characteristics of XPM. It is shown that, in a two channel WDM network, a probe signal’s SOP can be steered by controlling a high intensity pump signal’s SOP. This effect could be applied to make a wavelength converter. Experimental results show that the degree of polarization (DOP) of a probe signal degrades according to a mathematical model found in literature. The pump and probe signals are shown to experience maximum interaction, for orthogonal probe-pump SOP vector orientations. This may be problematic to polarization mode dispersion compensators. Additionally, experimental results point out that the SOP of a probe signal is much more active in the presence of a high intensity pump, as compared to the single signal transmission scenario

Optical technology Apollo extension system, phase A, volume 2. Section 3 - Experiments

Optical propagation in turbulent atmosphere, optical communication diagnostics, spaceborne heterodyne experiments, and ground support requirement

Aerial optical fibres in telecommunication systems : SOP and PMD monitoring, and tolerance of modulation formats

The topic of this thesis is aerial optical fibres in telecommunication systems: state of polarization (SOP) and polarization mode dispersion (PMD) monitoring and tolerance of modulation formats. Errors in optical fibre telecommunication systems are introduced when these polarization effects (SOP and PMD) change. These changes are so intense especially in aerial optical fibres. Part of the backbone of South Africa’s national grid includes long distances of aerial optical fibre between transmission exchange stations. The work in this thesis can be divided into three parts which all deal with the major aspects of PMD in deployed aerial optical fibres: characterization, environmental effects plus other perturbations, and tolerance of different modulation formats. In our work, SOP and PMD field measurements revealed that they both fluctuate more rapidly in deployed aerial optical fibres especially on windy and hot days. The SOP and PMD changes in the aerial optical fibres showed a significant correlation with these environmental parameters. SOP and PMD are stochastic in nature due to changes in the properties of the optical fibres and its positions because of both intrinsic and extrinsic perturbations. In our work, with only 184 PMD values measured and obtained by use of the FTB-5700 single-ended dispersion analyzer, the predicted theoretical Gaussian fit was obtained with a mean of 0.47 ps and standard deviation of 0.08 ps. This small standard deviation was justification for its robustness and accuracy. The statistical distributions for first-order polarization mode dispersion (FO-PMD) and second-order polarization mode dispersion (SO-PMD) for the first time were experimentally confirmed when measured using the FTB-5700 single-ended dispersion analyzer instrument for deployed aerial optical fibres. We were also able to determine the time scale over which to compensate FO-PMD in deployed aerial fibres using the directional time drift autocorrelation function method. It is slightly higher than 390 s for SOP measurements made on a particular windy and hot day. This is due to the fact that the changes of the PMD vector are known to be slower than the SOP changes. vi We also investigated the theoretical statistical distribution that corresponds to output SOP variations. The SOP variations can either be with wavelength (for buried fibre) or with time (for aerial fibre). Our results showed that the statistics of the relative SOP changes approached the distribution proposed by Foschini et al. (2000). Advanced optical modulation formats have become a key ingredient in the design of modern state-of-the-art wavelength-division-multiplexed (WDM) optical transmission systems. In our work, we investigated which of these advanced modulation formats is best suited for the South African network especially on systems that have links of aerial optical fibres. Keywords: aerial optical fibre, polarization mode dispersion (PMD), principal states of polarization (PSP), state of polarization (SOP), first-order PMD, second-order PMD

Compensation for distribution of timing and reference signals over optical fibre networks for telescope arrays

Significant advancements and developments have been made in optical frequency standards, in recent years. In order to verify the accuracy and preciseness of the disseminated RF signal, it is essential to compare its stability with the standards provided in literature as well as by metrology institutes. However, conventional frequency comparison techniques via satellites have extremely inferior stability qualities. As a result, the need for an alternative ultra-high precision RF transfer method presented itself. Highly accurate and precise frequency dissemination across optical fiber has proved a leading contender and a possible solution. When compared to conventional data transfer media, optical fiber has proven to be more superior and yields lower transmission errors and is immune to radio frequency interference. A further quality of optical fibre is that its transmission distance can be extended to greater degree than the traditional coaxial cable due to its low loss property. This thesis deals with the compensation of phase noise in single mode optical fibre. Phase noise degrades the performance and stability of the RF signal as well as the optical carrier frequency across long-haul optical networks. This work begins by experimentally demonstrating a unique and novel way for measuring the round-trip optical fibre latency times. The technique is based on all optical wavelength conversion using a stable PPS injection signal. The result highlighted the importance for active phase error compensation along a fibre link. Various computer simulations were used to study the influence of temperature fluctuation on the optical fibre. The first ever error signals generated at NMU was experimentally demonstrated. Results illustrated that, by minimizing the error voltage the phase difference between the transmitted and reference signals were reduced to zero. Performance analysis testing of the VCSEL phase correction actuator showed that majority of the dither iterations that induced the phase compensation took approximately 0.15 s. Residual frequency instabilities of 3.39791 x 10-12 at 1 s and 8.14848 x 10-12 at 103 s was measured when the 26 km G.655 fibre link was running freely. Experimental results further showed that the relative frequency stabilities measured at 1 s and 103 s were 4.43902 x 10-12 and 1.62055 x 10-13 during active compensation, respectively. The novel work presented in this thesis is exciting since the VCSEL is used as the optical source as well as the phase correction actuator. The benefits of such a device is that is reduces system costs and complexities

Frequency diversity wideband digital receiver and signal processor for solid-state dual-polarimetric weather radars

2012 Summer.Includes bibliographical references.The recent spate in the use of solid-state transmitters for weather radar systems has unexceptionably revolutionized the research in meteorology. The solid-state transmitters allow transmission of low peak powers without losing the radar range resolution by allowing the use of pulse compression waveforms. In this research, a novel frequency-diversity wideband waveform is proposed and realized to extenuate the low sensitivity of solid-state radars and mitigate the blind range problem tied with the longer pulse compression waveforms. The latest developments in the computing landscape have permitted the design of wideband digital receivers which can process this novel waveform on Field Programmable Gate Array (FPGA) chips. In terms of signal processing, wideband systems are generally characterized by the fact that the bandwidth of the signal of interest is comparable to the sampled bandwidth; that is, a band of frequencies must be selected and filtered out from a comparable spectral window in which the signal might occur. The development of such a wideband digital receiver opens a window for exciting research opportunities for improved estimation of precipitation measurements for higher frequency systems such as X, Ku and Ka bands, satellite-borne radars and other solid-state ground-based radars. This research describes various unique challenges associated with the design of a multi-channel wideband receiver. The receiver consists of twelve channels which simultaneously downconvert and filter the digitized intermediate-frequency (IF) signal for radar data processing. The product processing for the multi-channel digital receiver mandates a software and network architecture which provides for generating and archiving a single meteorological product profile culled from multi-pulse profiles at an increased data date. The multi-channel digital receiver also continuously samples the transmit pulse for calibration of radar receiver gain and transmit power. The multi-channel digital receiver has been successfully deployed as a key component in the recently developed National Aeronautical and Space Administration (NASA) Global Precipitation Measurement (GPM) Dual-Frequency Dual-Polarization Doppler Radar (D3R). The D3R is the principal ground validation instrument for the precipitation measurements of the Dual Precipitation Radar (DPR) onboard the GPM Core Observatory satellite scheduled for launch in 2014. The D3R system employs two broadly separated frequencies at Ku- and Ka-bands that together make measurements for precipitation types which need higher sensitivity such as light rain, drizzle and snow. This research describes unique design space to configure the digital receiver for D3R at several processing levels. At length, this research presents analysis and results obtained by employing the multi-carrier waveforms for D3R during the 2012 GPM Cold-Season Precipitation Experiment (GCPEx) campaign in Canada

Market capture by 30/20 GHz satellite systems, volume 2

Results of a telecommunications demand study are presented. Forecasts of demand for 30/20 GHz satellite systems, and the expected build up of traffic on these systems are given as a function of time for each of several operational scenarios

On optical-signal-to-noise ratio and polarization-mode-dispersion monitoring in optical networks.

Man-Hong Cheung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.Includes bibliographical references (leaves 88-97).Abstracts in English and Chinese.Chapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Drivers for Advanced Optical Performance Monitoring (OPM) Techniques --- p.1Chapter 1.2 --- OPM： Definition and Significance --- p.4Chapter 1.3 --- The Broad Spectrum of OPM --- p.5Chapter 1.3.1 --- Signal Loss Monitoring --- p.7Chapter 1.3.2 --- Signal Alignment Monitoring --- p.7Chapter 1.3.3 --- Signal Quality Monitoring --- p.7Chapter 1.4 --- Classification of OPM Techniques --- p.9Chapter 1.4.1 --- Time Domain vs. Frequency Domain Monitoring --- p.9Chapter 1.4.2 --- Analog Parameter vs. Digital Parameter Monitoring --- p.9Chapter 1.4.3 --- Three-Tier OPM --- p.11Chapter 1.5 --- Challenges and Requirements of OPM Techniques --- p.13Chapter 1.6 --- Thesis Outline --- p.15Chapter Chapter 2 --- Review on OSNR and PMD Monitoring --- p.16Chapter 2.1 --- Optical Signal-to-Noise-Ratio (OSNR) Monitoring --- p.16Chapter 2.2 --- Out-of-band OSNR Monitoring Techniques --- p.17Chapter 2.2.1 --- Optical Spectral Analysis --- p.17Chapter 2.2.2 --- Arrayed Waveguide Grating/Tunable Filter Assisted Power Measurements --- p.19Chapter 2.2.3 --- RF Spectral Analysis --- p.20Chapter 2.2.3.1 --- Low/High RF Noise Monitoring --- p.20Chapter 2.2.3.2 --- Subcarrier CNR Correlation --- p.20Chapter 2.3 --- In-band OSNR Monitoring Techniques --- p.20Chapter 2.3.1 --- Polarization-Assisted OSNR Monitoring --- p.21Chapter 2.3.1.1 --- Polarization Extinction Method --- p.21Chapter 2.3.1.2 --- Polarization-Nulling --- p.22Chapter 2.3.1.3 --- Degree-of-Polarization (DOP) Based OSNR Monitoring --- p.23Chapter 2.3.2 --- In-band RF Spectral Analysis --- p.24Chapter 2.3.2.1 --- Orthogonal Delayed Homodyne Method --- p.24Chapter 2.3.2.2 --- Half Clock Frequency Constellation MonitoringChapter 2.3.3 --- Interferometric Approach --- p.26Chapter 2.3.4 --- Nonlinear Method --- p.26Chapter 2.4 --- Polarization-Mode-Dispersion (PMD) Monitoring --- p.27Chapter 2.4.1 --- Degree-of-Polarization (DOP) Monitoring --- p.29Chapter 2.4.2 --- RF Spectral Analysis --- p.31Chapter 2.4.2.1 --- PMD-Induced RF Dip Power Measurement --- p.31Chapter 2.4.2.2 --- Subcarriei-Based RF Power Fading Measurement --- p.32Chapter 2.4.3 --- "Eye-Opening, Penalty Monitoring" --- p.33Chapter 2.4.4 --- Phase Diversity Detection --- p.33Chapter 2.4.5 --- Arrival Time Measurement of Polarization-Scrambled Light --- p.34Chapter 2.4.6 --- Nonlinear Method --- p.34Chapter 2.5 --- Summary of different OSNR and PMD Monitoring Methods . --- p.34Chapter Chapter 3 --- On Robustness of In-band Polarization-Assisted OSNR Monitoring Techniques against PMD --- p.36Chapter 3.1 --- Introduction --- p.36Chapter 3.2 --- Impact of PMD on Polarization-Nulling --- p.37Chapter 3.2.1 --- Numerical Results using Ideal Rectangular Pulse --- p.40Chapter 3.2.2 --- Numerical and Experimental Results using Super Gaussian Pulse --- p.43Chapter 3.3 --- Impact of PMD on DOP-based OSNR Monitoring --- p.46Chapter 3.3.1 --- Numerical and Experimental Results Using Ideal Rectangular and Super-Gaussian Pulses --- p.46Chapter 3.4 --- Impact of PMD on Orthogonal Delayed-Homodyne Method --- p.49Chapter 3.5 --- Summary --- p.53Chapter Chapter 4 --- PMD-Insensitive OSNR Monitoring Based on Polarization-Nulling with Off-Center Narrowband Filtering --- p.54Chapter 4.1 --- Introduction --- p.54Chapter 4.2 --- Previously Proposed Schemes based on Polarization-Nulling --- p.55Chapter 4.2.1 --- Improved Polarization-Nulling Technique --- p.55Chapter 4.2.2 --- Periodic Polarization Encoding Technique --- p.57Chapter 4.3 --- A new PMD-Insensitive OSNR Monitoring Technique based on Polarization-Nulling with Off-Center Narrowband Filtering --- p.58Chapter 4.3.1 --- Principle of Proposed Technique --- p.59Chapter 4.3.2 --- Theoretical Calculations --- p.62Chapter 4.3.3 --- Experimental Results --- p.65Chapter 4.3.4 --- "Effects of Filter Position, Filter Bandwidth, and Filter Detuning" --- p.69Chapter 4.4 --- Summary --- p.71Chapter Chapter 5 --- Simultaneous OSNR and PMD Monitoring using Polarization Techniques --- p.72Chapter 5.1 --- Introduction --- p.72Chapter 5.2 --- Previously Proposed Scheme --- p.72Chapter 5.3 --- Simultaneous OSNR and PMD Monitoring by Enhanced RF Spectral Analysis --- p.74Chapter 5.3.1 --- Proposed Scheme --- p.75Chapter 5.3.2 --- Experimental Results --- p.77Chapter 5.4 --- DOP-based Simultaneous OSNR and PMD Monitoring --- p.80Chapter 5.4.1 --- Principle of Operation --- p.81Chapter 5.4.2 --- Experimental Results --- p.82Chapter 5.5 --- Summary --- p.84Chapter Chapter 6 --- Conclusions and Future Works --- p.85Chapter 6.1 --- Summary of the Thesis --- p.85Chapter 6.2 --- Future Works --- p.86Bibliography --- p.88Appendix - List of publications --- p.9

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Proceedings of the Fourteenth NASA Propagation Experimenters Meeting (NAPEX 14) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

The NASA Propagation Experimenters Meeting (NAPEX), supported by the NASA Propagation Program, is convened annually to discuss studies made on radio wave propagation by investigators from domestic and international organizations. NAPEX XIV was held on May 11, 1990, at the Balcones Research Centers, University of Texas, Austin, Texas. The meeting was organized into two technical sessions: Satellite (ACTS) and the Olympus Spacecraft, while the second focused on the fixed and mobile satellite propagation studies and experiments. Following NAPEX XIV, the ACTS Miniworkshop was held at the Hotel Driskill, Austin, Texas, on May 12, 1990, to review ACTS propagation activities since the First ACTS Propagation Studies Workshop was held in Santa Monica, California, on November 28 and 29, 1989