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The polarisation Sagnac speedmeter interferometer has the potential to replace the Michelson interferometer as the instrumental basis for future generations of ground-based gravitational wave detectors. The quantum noise benefit of this speedmeter is dependent on high-quality polarisation optics, the polarisation beam-splitter (PBS) and quarter-waveplate (QWP) optics that are key to this detector configuration and careful consideration of the effect of birefringence in the arm cavities of the interferometer. A PBS with an extinction ratio of better than 4000 in transmission and 700 in reflection for a 41° angle of incidence was characterised along with a QWP of birefringence of. The cavity mirror optics of a 10 m prototype polarisation Sagnac speedmeter were measured to have birefringence in the range 1 × 10−3 to 2 × 10−5 radians. This level of birefringence, along with the QWP imperfections, can be cancelled out by careful adjustment of the QWP angle, to the extent that the extinction ratio of the PBS is the leading limitation for the polarisation Sagnac speedmeter in terms of polarisation effects. [ABSTRACT FROM AUTHOR]

Technologies, design aspects and recent progresses for future gravitational wave (GW) detectors are mentioned in this summary of the C4 session of the Amaldi 10 conference. [ABSTRACT FROM AUTHOR]

Abstract: Focussing particularly on solid-state laser systems, the phase-noise penalties of laser injection-locking and electro-optical phase-locking are derived using linearised quantum mechanical models. The fundamental performance limit (minimum achievable output phase noise) for an injection-locked laser (IJL) system at low frequencies is equal to that of a standard phase-insensitive amplifier, whereas, in principle, that of a phase-locked laser (PLL) system can be better. At high frequencies, the output phase noise of the IJL system is limited by that of the master laser, while that of the PLL system tends to a weighted sum of contributions from the master and slave laser fields. Under conditions of large amplification, particularly where there has been significant attenuation, the noise penalties are shown to be substantial. Nonideal photodetector characteristics are shown to add significantly to the noise penalties for the PLL system. [Copyright &y& Elsevier]