ACIGA/LIGO High Optical Power Test Facility

The high-frequency (200 Hz – 2 kHz) sensitivity of gravitational wave interferometers (GWI) is limited by fluctuations in the number of photons observed by the detectors. Thus, advanced GWI for gravitational astronomy must have 200-500 kW of optical power stored in their 4 km long optical cavities. However, residual optical absorption by the substrates and coatings of the mirrors will result in distortion of the optical wavefront, seriously limiting the sensitivity of the interferometer.

The high optical power test facility (HOPTF) is a collaboration between the Australian Consortium for Interferometric Astronomy (ACIGA), of which the Optics and Photonics group is a founding member, and the US LIGO project. It will undertake a series of tests to investigate the effect of the absorption and develop sensors and actuators for wavefront control. It will also be used to investigate parametric instabilities that might occur due to the coupling between the large optical spring, produced by the high stored power, and the acoustic modes of the mirrors.

The Optics and Photonics group has designed the series of tests to be conducted at the HOPTF, and are developing specialized hardware for these tests, including a single frequency, diffraction limited 10W Nd:YAG laser and ultra-sensitive Hartmann wavefront sensors. See the publications listed below for latest results.

Publications

• Status of the Australian Consortium for Interferometric Gravitational Astronomy, McClelland D.E. and the ACIGA consortium, Class. Quantum Grav. 23, S41 - S49 (2006)
• Gingin High Optical Power Tests Facility, Zhao C. and the ACIGA consortium, Journal of Physics: Conference Series 32, 368-373 (2006)
• Compensation of Strong Thermal Lensing in High Optical Power Cavities, Zhao C. and the ACIGA consortium, Phys. Rev. Lett. 96, 231101 (2006)
• Technology developments for ACIGA high power test facility for advanced interferometry, Barriga P. and the ACIGA consortium, Class. Quantum Grav. 22, S199 - S208 (2005)
• ACIGA’s High Optical Power Test Facility, Ju L. and the ACIGA consortium, Class. Quantum Grav. 21, S887 - S893 (2004)
• Status of ACIGA High Power Test Facility for Advanced Interferometry, P. Barriga and the ACIGA consortium, Proceedings of the SPIE 5500, 70-79 (2004)

Personnel

Mr Aidan Brooks
Mr David Hosken
Dr Damien Mudge
Prof Jesper Munch
A/Prof. Peter Veitch