A5084488920- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- Geophysics and Sensor Technology
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Seismic Waves and Analysis
- Advanced Frequency and Time Standards
- Advanced Fiber Optic Sensors
- Ultrasonics and Acoustic Wave Propagation
- Radio Astronomy Observations and Technology
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- Statistical and numerical algorithms
- Mechanical and Optical Resonators
- Astronomical Observations and Instrumentation
- Cold Atom Physics and Bose-Einstein Condensates
- Thermography and Photoacoustic Techniques
- Adaptive optics and wavefront sensing
- Black Holes and Theoretical Physics
- Photonic and Optical Devices
- Structural Health Monitoring Techniques
- Seismology and Earthquake Studies
- Superconducting Materials and Applications
University of Glasgow
2014-2023
Massachusetts Institute of Technology
2018
Louisiana State University
2017
University of Illinois Urbana-Champaign
2017
University of Strathclyde
2002-2014
Goddard Space Flight Center
2014
Cardiff University
2011
Carleton College
2011
California Institute of Technology
2011
Andrews University
2011
The German–British laser-interferometric gravitational wave detector GEO 600 is in its 14th year of operation since first lock 2001. After participated science runs with other first-generation detectors, a program known as GEO-HF began 2009. goal was to improve the sensitivity at high frequencies, around 1 kHz and above,with technologically advanced yet minimally invasive upgrades. Simultaneously, would record quality data between commissioning activities. As early 2014, all planned upgrades...
Photon shot noise, arising from the quantum-mechanical nature of light, currently limits sensitivity all gravitational wave observatories at frequencies above one kilohertz. We report a successful application squeezed vacuum states light GEO\,600 observatory and demonstrate for first time reduction quantum noise up to $6.03 \pm 0.02$ dB in kilometer-scale interferometer. This is equivalent high increasing laser power circulating interferometer by factor four. Achieving this milestone, key...
Abstract The nature of dark matter remains unknown to date, although several candidate particles are being considered in a dynamically changing research landscape 1 . Scalar field is prominent option that explored with precision instruments, such as atomic clocks and optical cavities 2–8 Here we describe direct search for scalar using gravitational-wave detector, which operates beyond the quantum shot-noise limit. We set new upper limits on coupling constants function its mass, by excluding...
For almost 20 years, advanced techniques have been developed and tested at the GEO 600 laser-interferometric gravitational wave detector. Many of these innovations improved sensitivity could be shown to consistent with stable reliable operation detectors. We review performance show how they influenced upgrades other detectors worldwide. In second half paper, we consider continues pioneer new for future describe some methods in detail present results on improve and/or stability possibly
We propose an upgrade to Advanced LIGO (aLIGO), named LIGO-LF, that focuses on improving the sensitivity in 5--30 Hz low-frequency band, and we explore upgrade's astrophysical applications. present a comprehensive study of detector's technical noises show with technologies currently under development, such as interferometrically sensed seismometers balanced-homodyne readout, LIGO-LF can reach fundamental limits set by quantum thermal down 5 Hz. These are also directly applicable future...
Ultrasound is a valuable tool for the detection of damage in structures and characterization material properties. Its conventionally done by piezoelectric transducers, however fiber-optic sensors can operate over greater range frequencies also yield information on direction wave propagation. The interaction between fiber ultrasound both demonstrates integrating features intrinsic presents new opportunities ultrasonic detection, offering enormous diversity polar frequency response. This paper...
Brownian noise of dielectric mirror coatings is expected to be one the limiting sources, at peak sensitivity, next generation ground based interferometric gravitational wave (GW) detectors. The use higher-order Laguerre–Gauss (LG) beams has been suggested reduce effect coating thermal in future generations In this paper we describe first test interferometry with LG an environment similar a full-scale detector. We compare performance modes and fundamental mode beams, injected into 10 m long...
The second generation of large scale interferometric gravitational wave (GW) detectors will be limited by quantum noise over a wide frequency range in their detection band. Further sensitivity improvements for future upgrades or new beyond the motivate development measurement schemes to mitigate impact these instruments. Two strands are being pursued reach this goal, focusing both on modifications well-established Michelson detector configuration and different topologies. In paper, we...
The second generation of interferometric gravitational wave detectors are quickly approaching their design sensitivity. For the first time these will become limited by quantum backaction noise. Several evasion techniques have been proposed to further increase detector Since most proposals rely on a flexible readout full amplitude- and phase-quadrature space output light field, balanced homodyne detection is generally expected replace currently used DC readout. Up now, little investigation...
We report on the first demonstration of a fully suspended 10 m Fabry-Perot cavity incorporating waveguide grating as coupling mirror.The was kept resonance by reading out length fluctuations via Pound-Drever-Hall method and employing feedback to laser frequency.From achieved finesse 790 reflectivity determined exceed 99.2 % at wavelength 1064 nm, which is in good agreement with rigorous simulations.Our design based tantala fused silica included ≈ 20 nm thin etch stop layer made Al 2 O 3 that...
Speedmeters are known to be quantum non-demolition devices and, by potentially providing sensitivity beyond the standard limit, become interesting for third generation gravitational wave detectors. Here we introduce a new configuration, sloshing-Sagnac interferometer, and compare it more established ring-Sagnac interferometer. The interferometer is designed provide improved noise limited lower coating thermal than position meter interferometers employed in current We of interferometers,...
Abstract High purity fused silica has become the cornerstone choice for use in final monolithic stage of mirror suspensions gravitational wave observatories Advanced LIGO (aLIGO) and Virgo (AdV). The ultra-low thermal noise contributed by these is one key improvements that permitted Nobel prize winning first direct measurement waves 2015. This paper outlines situ study undertaken to analyse aLIGO Hanford detector suspensions. We analysed short operational periods this detector, when high...
In this article we describe our efforts of extending demand-side control concepts to the application in portable electronic devices, such as laptop computers, mobile phones and tablet computers. As these devices feature built-in energy storage (in form batteries) ability run complex routines, they are well-suited for implementation smart charging concepts. We developed simple hardware software based prototypes controllers a computer that steer process depending on frequency electricity grid...
Abstract: This is a review of the optical generation and detection ultrasound on work carried out in different techniques at Strathclyde University. We start by pointing some limitations conventional ultrasonic transducers show how use optical‐based can overcome them. After explaining laser works, we will describe compare advantages disadvantages three techniques. Finally, applications which appear to have promising future.
The response of an integrating optical fiber (OF) ultrasound detector to varying sensor length and orientation with respect the acoustic source has been experimentally investigated using Lamb waves, analyzed theoretically, simulated in Matlab environment. experimental results theoretical models show very similar trends both sensitivity directivity. These properties have immense potential as a new tool damage detection systems. Finally, we briefly discuss prospects for use these systems,...
With the recent detection of gravitational waves (GWs), marking start new field GW astronomy, push for building more sensitive laser-interferometric wave detectors (GWDs) has never been stronger. Balanced homodyne (BHD) allows a quantum-noise (QN) limited readout arbitrary light quadratures, and therefore suggested as vital block upgrades to Advanced LIGO third-generation observatories. In terms practical implementation BHD, we develop full framework analyzing static optical high-order modes...
Optical rigidity will play an important role in future generations of gravitational wave (GW) interferometers which employ high laser power order to reach and exceed the standard quantum limit. Several experiments have demonstrated optical spring effect for very low weight mirror masses. In this paper we extend a mass frequency regime more directly applicable GW detectors. Using end demonstrate resonant at stiffness 9.4 ×105 N m−1. The may also be useful application as readout bar or lever...
In this paper we describe and compare two methods for detecting Lamb waves used damage detection. One is a polarimetric sensor that integrates the pressure effects of acoustic wave along its length, whilst other Bragg grating measures linear strain in effect point sensor. Both sensors are highly directional, which gives benefits signal detection source location. We demonstrate both location discuss advantages disadvantages sensors.
The measurement of changes in the properties ultrasonic Lamb waves propagating through structural material has frequently been proposed as a method for detection damage. In this paper we describe work that uses optical fibre sensors to detect and show directional these allow us not only damage, but also locate it. We look at two types sensor, polarimetric sensor Bragg grating. measures change birefringence caused by pressure wave ultrasound acting upon This is an integrated since length...
The Sagnac speed metre topology has been identified as a promising technique to reduce quantum back-action in gravitational-wave interferometers. However, imbalance of the main beamsplitter shown increase coupling laser noise detection port, thus reducing superiority metre, compared conventional approaches, particular at low frequencies. In this paper, we show that by implementing balanced homodyne readout scheme with suitable choice point from which local oscillator (LO) is derived, excess...
Optical rigidity will play an important role in improving the sensitivity of future generations gravitational wave (GW) interferometers, which employ high laser power order to reach and exceed standard quantum limit. Several experiments have demonstrated combined effect two optical springs on a single system for very low-weight mirror masses or membranes. In this paper we investigate complex interactions between multiple surrounding apparatus comparable dynamics large-scale GW detector....
We describe and compare two novel methods of detecting ultrasonic Lamb waves used for damage detection location, then go on to their characteristics with those more conventional PZT transducers. The are measurements the change in polarization state light an optical fibre changes reflected power from a Bragg grating. Since different transducers measure properties by methods, relative sensitivities S<sub>0</sub> A<sub>0</sub> modes can also vary. This be interest because, instance, mode is...
We present two options for length sensing and control of a three-mirror coupled cavity. The the first cavity uses amplitude or single sideband modulation phase in combination with beat-frequency demodulation scheme, whereas scheme second incorporates demodulation. theoretical experimental performance is discussed as well relevance to research programme develop interferometric techniques application future gravitational wave detectors.