Stimulated Brillouin Scattering in Integrated Circuits: Platforms and Applications

Coherent interactions between light and sound have been of significant interest since the invention of the laser. Stimulated Brillouin scattering (SBS) is a type of coherent interaction where light is scattered from optically generated acoustic waves. SBS is a powerful tool for optical and microwave signal processing, with applications ranging from telecommunications and Radar, to spatial sensing and microscopy. Over the last decade there has been increasing interest in the investigation of Brillouin scattering at device scales smaller than the wavelength of light. New interactions with the waveguide boundaries in these systems are capable of altering the strength of SBS, from complete suppression to orders of magnitude increases. The landmark demonstration of Brillouin scattering in planar waveguides, just six years ago, represents a new frontier for this field. This work explores the effective generation and harnessing of stimulated Brillouin scattering within modern photonic circuits. After establishing the foundations of linear and nonlinear optical circuits, we investigate the Brillouin processes available in multimode waveguides. We experimentally demonstrate giant Brillouin amplification using spiral waveguides consisting of soft-glass materials. We then integrate this soft-glass onto the standard platform for photonic circuits, silicon on insulator, without any reduction in performance. We apply these advanced devices to the field of microwave photonics and create high suppression microwave filters with functionality far beyond traditional electronic circuits. This thesis is a significant step towards Brillouin enabled integrated photonic processors

Tracking Vibrio: Population Dynamics and Community Ecology in Alabama Estuaries

Integral parts of local culture along the Eastern Mississippi Sound System (EMSS)- eating raw oysters and fishing- can involve contact with vectors of pathogenic Vibrio spp. bacteria. High mortality rates from vibrio infections demonstrate the need for improved understanding of V. vulnificus and V. parahaemolyticus dynamics in the region. This study assessed: 1) meteorological, 2) hydrographic, and 3) biological correlates of V. parahaemolyticus and V. vulnificus in the EMSS from April-October 2019. Spearman’s correlations, linear mixed models, and non-metric dimensional scaling identified significant relationships between Vibrio spp., abiotic, and biotic parameters of the ecosystem. Vibrio spp. population dynamics were largely driven by site-based variation, with sites closest to freshwater inputs having the highest Vibrio spp. abundances. These data also suggest that the E-W wind scalar may be a novel Vibrio spp. correlate in the EMSS, and there may be a salinity effect on V. vulnificus-particle associations. Additionally, V. vulnificus abundances were correlated to harmful algal species like Akashiwo sanguinea and Heterocapsa spp. Correlates from this study can be used to inform the next iteration of predictive Vibrio models for the EMSS region

SPECIALIZED SERVICES FOR COMMERCIALLY SEXUALLY EXPLOITED CHILDREN IN THE CHILD WELFARE SYSTEM

Commercial Sexual Exploitation of Children (CSEC) is a prevalent global crisis including a range of crimes and activities involving the sexual abuse and exploitation of children for financial and non-financial gain. Due to the vulnerability of children and youth who have been in the child welfare system, this population is at a much higher risk of falling victim to CSEC. This qualitative research study focused on the resources available and the knowledge of community professionals who have regular interactions with CSEC victims, such as social workers, licensed clinicians, law enforcement, and community advocates. Data was collected through video and phone interviews (in observation of COVID-19 safety protocols) with ten professionals who work with this population. Participants were recruited by the researchers. Participants were consented prior to participation and debriefed following their interviews. The data collected from the interviews was organized via a color-coded approach using descriptive analysis. This study found that most of the participants who come into contact with at risk or active CSEC victims utilize some type of identification tool. Additionally, this study confirmed that professionals in the community are aware and have community resources that provide direct intervention services. However, resources for this population are limited and there are barriers to maintaining contact with the youth due to confidentiality and the isolating and criminal nature of the exploitation, which impedes the professionals’ ability to gauge whether or not the services are effective. Furthermore, many participants reported that they recognize CSEC is a growing crisis in the community and that a lack of funding prevents more permanent and dependable community intervention and crisis programs, which are vital to supporting this vulnerable population. This study makes contributions to micro, mezzo, and macro social work by providing the observations of professionals including social workers in the community, who have regular interaction with CSEC victims and knowledge of the barriers that prevent this population from receiving the most encompassing, supportive, and trauma-informed services. Study limitations include the small sample size and non-probability sampling method

Validity and practical utility of accelerometry for the measurement of in-hand physical activity in horses

Background: Accelerometers are valid, practical and reliable tools for the measurement of habitual physical activity (PA). Quantification of PA in horses is desirable for use in research and clinical settings. The objective of this study was to evaluate a triaxial accelerometer for objective measurement of PA in the horse by assessment of their practical utility and validity. Horses were recruited to establish both the optimal site of accelerometer attachment and questionnaire designed to explore owner acceptance. Validity and cut-off values were obtained by assessing PA at various gaits. Validation study- 20 horses wore the accelerometer while being filmed for 10 min each of rest, walking and trotting and 5 mins of canter work. Practical utility study- five horses wore accelerometers on polls and withers for 18 h; compliance and relative data losses were quantified. Results: Accelerometry output differed significantly between the four PA levels (P <0•001) for both wither and poll placement. For withers placement, ROC analyses found optimal sensitivity and specificity at a cut-off of <47 counts per minute (cpm) for rest (sensitivity 99.5 %, specificity 100 %), 967–2424 cpm for trotting (sensitivity 96.7 %, specificity 100 %) and ≥2425 cpm for cantering (sensitivity 96.0 %, specificity 97.0 %). Attachment at the poll resulted in optimal sensitivity and specificity at a cut-off of <707 counts per minute (cpm) for rest (sensitivity 97.5 %, specificity 99.6 %), 1546–2609 cpm for trotting (sensitivity 90.33 %, specificity 79.25 %) and ≥2610 cpm for cantering (sensitivity 100 %, specificity 100 %) In terms of practical utility, accelerometry was well tolerated and owner acceptance high. Conclusion: Accelerometry data correlated well with varying levels of in-hand equine activity. The use of accelerometers is a valid method for objective measurement of controlled PA in the horse

All-integrated universal RF photonic spectral shaper

We demonstrate a microwave photonic spectral shaper in a silicon chip enabling distinct phase and amplitude modulation transformation. We show unprecedented RF filtering through monolithic integration of the spectral shaper with tunable ring resonators

Low-error and broadband microwave frequency measurement in a silicon chip

Instantaneous frequency measurement (IFM) of microwave signals is a fundamental functionality for applications ranging from electronic warfare to biomedical technology. Photonic techniques, and nonlinear optical interactions in particular, have the potential to broaden the frequency measurement range beyond the limits of electronic IFM systems. The key lies in efficiently harnessing optical mixing in an integrated nonlinear platform, with low losses. In this work, we exploit the low loss of a 35 cm long, thick silicon waveguide, to efficiently harness Kerr nonlinearity, and demonstrate the first on-chip four-wave mixing (FWM) based IFM system. We achieve a large 40 GHz measurement bandwidth and record-low measurement error. Finally, we discuss the future prospect of integrating the whole IFM system on a silicon chip to enable the first reconfigurable, broadband IFM receiver with low-latency.Comment: 13 pages, 7 figure

Implementation of a fully automated process purge-and-trap gas chromatograph at an environmental remediation site

The AQUASCAN, a commercially available, fully automated purge-and-trap gas chromatograph from Sentex Systems Inc., was implemented and evaluated as an in-field, automated monitoring system of contaminated groundwater at an active DOE remediation site in Pinellas, FL. Though the AQUASCAN is designed as a stand alone process analytical unit, implementation at this site required additional hardware. The hardware included a sample dilution system and a method for delivering standard solution to the gas chromatograph for automated calibration. As a result of the evaluation the system was determined to be a reliable and accurate instrument. The AQUASCAN reported concentration values for methylene chloride, trichloroethylene, and toluene in the Pinellas ground water were within 20% of reference laboratory values