This document constitutes an excerpt of the Technical Design Report for the second stage of the "Any Light Particle Search" (ALPS-II) at DESY as submitted to the DESY PRC in August 2012 and reviewed ...in November 2012. ALPS-II is a "Light Shining through a Wall" experiment which searches for photon oscillations into weakly interacting sub-eV particles. These are often predicted by extensions of the Standard Model and motivated by astrophysical phenomena. The first phases of the ALPS-II project were approved by the DESY management on 21 February, 2013.
An ultra-stable, high-power cw Nd:YAG laser system, developed for the ground-based gravitational wave detector Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory), was comprehensively ...characterized. Laser power, frequency, beam pointing and beam quality were simultaneously stabilized using different active and passive schemes. The output beam, the performance of the stabilization, and the cross-coupling between different stabilization feedback control loops were characterized and found to fulfill most design requirements. The employed stabilization schemes and the achieved performance are of relevance to many high-precision optical experiments.
The German-British laser-interferometric gravitational wave detector GEO 600 is in its 14th year of operation since its first lock in 2001. After GEO 600 participated in science runs with other ...first-generation detectors, a program known as GEO-HF began in 2009. The goal was to improve the detector sensitivity at high frequencies, around 1 kHz and above,with technologically advanced yet minimally invasive upgrades. Simultaneously, the detector would record science quality data in between commissioning activities. As of early 2014, all of the planned upgrades have been carried out and sensitivity improvements of up to a factor of four at the high-frequency end of the observation band have been achieved. Besides science data collection, an experimental program is ongoing with the goal to further improve the sensitivity and evaluate future detector technologies. We summarize the results of the GEO-HF program to date and discuss its successes and challenges.
Second‐generation interferometric gravitational wave detectors require high‐power lasers with approximately 200 W of output power in a linear polarized, single‐frequency, fundamental‐mode laser beam. ...Furthermore very high temporal and spatial stability is required. This paper discusses the design of a 200 W pre‐stabilized laser (PSL) system and the underlying concepts. The PSL requirements for advanced gravitational wave detectors as well as for the laser system are described. The laser stabilization scheme proposed for the Advanced LIGO gravitational wave detector and the so‐called diagnostic breadboard will serve as examples to explain the general laser stabilization concepts and the achieved performance and its limitations.
Second‐generation interferometric gravitational wave detectors require high‐power lasers with approximately 200W of output power in a linear polarized, single‐frequency, fundamental‐mode laser beam. Furthermore very high temporal and spatial stability is required. This paper discusses the design of a 200W pre‐stabilized laser (PSL) system and the underlying concepts. The PSL requirements for advanced gravitational wave detectors as well as for the laser system are described.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Advanced techniques in GEO 600 Affeldt, C; Danzmann, K; Dooley, K L ...
Classical and quantum gravity,
11/2014, Volume:
31, Issue:
22
Journal Article
Peer reviewed
Open access
For almost 20 years, advanced techniques have been developed and tested at the GEO 600 laser-interferometric gravitational wave detector. Many of these innovations have improved the sensitivity of ...GEO 600 and could be shown to be consistent with stable and reliable operation of gravitational wave detectors. We review the performance of these techniques and show how they have influenced the upgrades of other detectors worldwide. In the second half of the paper, we consider how GEO 600 continues to pioneer new techniques for future gravitational wave detectors. We describe some of the new methods in detail and present new results on how they improve the sensitivity and/or the stability of GEO 600 and possibly of future detectors.
We have investigated the generation of highly pure higher-order Laguerre-Gauss (LG) beams at high laser power of order 100 W, the same regime that will be used by second-generation gravitational wave ...interferometers such as Advanced LIGO. We report on the generation of a helical-type LG33 mode with a purity of order 97% at a power of 83 W, the highest power ever reported in literature for a higher-order LG mode. This is a fundamental step in proving technical readiness for use of LG beams in gravitational wave interferometers of future generations.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
All first-generation large-scale gravitational wave detectors are operated at the dark fringe and use a heterodyne readout employing radio frequency (RF) modulation-demodulation techniques. However, ...the experience in the currently running interferometers reveals several problems connected with a heterodyne readout, of which phase noise of the RF modulation is the most serious one. A homodyne detection scheme (DC-readout), using the highly stabilized and filtered carrier light as a local oscillator for the readout, is considered to be a favourable alternative. Recently a DC-readout scheme has been implemented on the GEO 600 detector. We describe the results of first measurements and give a comparison of the performance achieved with homodyne and heterodyne readout. The implications of the combined use of DC-readout and signal recycling are considered.
A solid-state laser system for the next generation of gravitational wave detectors with an output power of 220 W at the wavelength of 1064 nm is presented. Single-frequency operation of the laser was ...achieved by injection-locking of a high-power ring oscillator to an amplified non-planar ring oscillator (NPRO) following the Pound–Drever–Hall scheme. The high-power stage which features four longitudinally pumped Nd:YAG laser crystals as active media in a ring resonator configuration was designed for reliable long term operation. Using a non-confocal ring cavity to filter the output beam, a pure TEM
00
mode with 168 W output power was obtained.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The upgrade of GEO 600 Lück, H; Affeldt, C; Degallaix, J ...
Journal of physics. Conference series,
05/2010, Volume:
228, Issue:
1
Journal Article
Peer reviewed
Open access
The German/ British gravitational wave detector GEO 600 is in the process of being upgraded. The upgrading process of GEO 600, called GEO-HF, will concentrate on the improvement of the sensitivity ...for high frequency signals and the demonstration of advanced technologies. In the years 2009 to 2011 the detector will undergo a series of upgrade steps, which are described in this paper.
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