Development of a broadband visible to infrared astrocomb

Motivated by the applications of high-resolution spectroscopy in astrophotonics, this thesis presents the experimental work and development of a broadband wide-mode-spacing astrocomb system as part of the UK consortium for the High Resolution Spectrograph (HIRES) in the forthcoming Extremely Large Telescope (ELT). A 1-GHz Ti:sapphire laser served as the master source comb of the system, pumping a visible broadband supercontinuum and a phase-coherent PPKTP-based degenerate optical parametric oscillator (OPO), spectrally broadened in highly non-linear fibre. The system was fully stabilised, and provided an atomically-traceable 1-GHz astrocomb across nearly two octaves from 500–2200 nm. Residual noise from the dither-locked OPO hindered subsequent modal filtering in a Fabry Perot cavity motivating development of a dither-free technique exploiting the always-present parasitic sum-frequency light. This locking protocol provided a sixfold lower relative intensity noise and nearly five times less power fluctuation than the dither-locked version, leading to successful modal filtering from 1150–1800 nm. The spectra of the filtered output were recovered using Fourier transform spectroscopy, with the 10-GHz comb mode spacings directly resolved optically. Through linear regression, fCEO was found to be 565.7 MHz ± 64.3 MHz and frep was calculated as 992.1 MHz ± 352 Hz. Individual comb mode values were identified with high accuracy using the comb equation. This technique was verified with a heterdyne experiment between the Ti:sapphire comb source and a Rb-referenced CW laser to which the FTS was referenced. An alternative approach for visible wavelength generation was investigated using a PPLN waveguide. Using a sample optimised for 1560 nm, 1.5 % of our coupled degenerate OPO input was up-converted to second harmonic generation as well as sum-frequency mixing and showed a good agreement with modelled results, providing confidence in the ability to use such simulations to design fully grating-engineered PPLN waveguide for broadband conversion

Advances in Optical Amplifiers

Optical amplifiers play a central role in all categories of fibre communications systems and networks. By compensating for the losses exerted by the transmission medium and the components through which the signals pass, they reduce the need for expensive and slow optical-electrical-optical conversion. The photonic gain media, which are normally based on glass- or semiconductor-based waveguides, can amplify many high speed wavelength division multiplexed channels simultaneously. Recent research has also concentrated on wavelength conversion, switching, demultiplexing in the time domain and other enhanced functions. Advances in Optical Amplifiers presents up to date results on amplifier performance, along with explanations of their relevance, from leading researchers in the field. Its chapters cover amplifiers based on rare earth doped fibres and waveguides, stimulated Raman scattering, nonlinear parametric processes and semiconductor media. Wavelength conversion and other enhanced signal processing functions are also considered in depth. This book is targeted at research, development and design engineers from teams in manufacturing industry, academia and telecommunications service operators

Plasma chemistry of fluorocarbon RF discharges used for dry etching

ter verkrijging van de graad van doctor aan de Technische Universiteit Eindhoven, op gezag van de Rector Magnificus, prof.dr. J.H. van Lint, voor een commissie aangewezen door het College van Dekanen in het openbaar te verdedigen op dinsdag 10 september 1991 te 16.00 uur doo

14th Conference on Dynamical Systems Theory and Applications DSTA 2017 ABSTRACTS

From Preface: This is the fourteen time when the conference “Dynamical Systems – Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and the Ministry of Science and Higher Education. It is a great pleasure that our invitation has been accepted by so many people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcome nearly 250 persons from 38 countries all over the world. They decided to share the results of their research and many years experiences in the discipline of dynamical systems by submitting many very interesting papers. This booklet contains a collection of 375 abstracts, which have gained the acceptance of referees and have been qualified for publication in the conference proceedings [...]

Improving the Limit on the Electron EDM: Data Acquisition and Systematics Studies in the ACME Experiment

The ACME collaboration has completed a measurement setting a new upper limit on the size of the electron's permanent electric dipole moment (EDM). The existence of the EDM is well motivated by theories extending the standard model of particle physics, with predicted sizes very close to the current experimental limit. The new limit was set by measuring spin precession within the metastable H state of the polar molecule thorium monoxide (ThO). A particular focus here is on the automated data acquisition system developed to search for a precession phase odd under internal and external reversal of the electric field. Automated switching of many different experimental controls allowed a rapid diagnosis of major systematics, including the dominant systematic caused by non-reversing electric fields and laser polarization gradients. Polarimetry measurements made it possible to quantify and minimize the polarization gradients in our state preparation and probe lasers. Three separate measurements were used to determine the electric field that did not reverse when we tried to switch the field direction. The new bound of |de|-29 e cm is over an order of magnitude smaller than previous limits, and strongly limits T-violating physics at TeV energy scales.Physic