Frank Seifert

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We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build(More)
A tunable regenerative Ti:sapphire amplifier system working at a 1-kH(z) repetition rate pumps an optical parametric generator providing near-infrared pulses tunable in the wavelength range from 1 to 2.5 microm. The signal and idler pulses with a duration below 100 fs are mixed in a AgGaS(2) crystal to generate pulses at the difference frequency. The(More)
An amplifier design for efficient amplification of linearly polarized fundamental mode lasers is presented. The concept was verified by amplifying single-frequency input powers from 1 W to 20 W into output power ranges of 35 W up to 65 W. Beam quality measurements with a mode-analyzer cavity showed only minor beam quality degradation due to the(More)
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(More)
We present results on the power stabilization of a Nd:YAG laser in the frequency band from 1 Hz to 100 kHz. High-power, low-noise photodetectors are used in a dc-coupled control loop to achieve relative power fluctuations down to 5 x 10(-9) Hz(-1/2) at 10 Hz and 3.5 x 10(-9) Hz(-1/2) up to several kHz, which is very close to the shot-noise limit for 80 mA(More)
Experiments on a high-power end-pumped Nd:YAG rod laser with an efficient birefringence compensation will be presented. A linearly polarized output power of 114 W with an M2-value of 1.05 was realized. Furthermore, the from our best knowledge highest injection-locked singlefrequency output power of 87 W in a nearly diffraction-limited beam was demonstrated.
A tunable 1-kHz repetition-rate regenerative Ti:sapphire amplifier system is used to produce 200-fs vacuum-ultraviolet pulses in the range of 172.7-187 nm by phase-matched sum-frequency mixing in lithium triborate of the Ti:sapphire's fourth harmonic and a parametrically generated infrared pulse.
Second generation gravitational wave detectors require high power lasers with several 100W of output power and with very low temporal and spatial fluctuations. In this paper we discuss possible setups to achieve high laser power and describe a 200W prestabilized laser system (PSL). The PSL noise requirements for advanced gravitational wave detectors will be(More)
In order to increase the sensitivity of interferometric gravitational wave detectors several 100 kW of laser power have to circulate in the cavity arms. Therefore, interferometer arms with additional internal high finesse Fabry–Perot cavities will be used. Also a laser input source with nearly 200 W of output power in a high beam quality and a stable(More)
We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from(More)