J. Munch

Resonantly diode-pumped continuous-wave and Q-switched Er:YAG laser at 1645 nm.

We describe an efficient Er:YAG laser that is resonantly pumped using continuous-wave (CW) laser diodes at 1470 nm. For CW lasing, it emits 6.1 W at 1645 nm with a slope efficiency of 36%, the highest efficiency reported for an Er:YAG laser that is pumped in this manner. In Q-switched operation, the laser produces diffraction-limited pulses with an average power of 2.5 W at 2 kHz PRF. To our knowledge this is the first Q-switched Er:YAG laser resonantly pumped by CW laser diodes.

AIGO: a southern hemisphere detector for the worldwide array of ground-based interferometric gravitational wave detectors

This paper describes the proposed AIGO detector for the worldwide array of interferometric gravitational wave detectors. The first part of the paper summarizes the benefits that AIGO provides to the worldwide array of detectors. The second part gives a technical description of the detector, which will follow closely the Advanced LIGO design. Possible technical variations in the design are discussed.

Gingin High Optical Power Test Facility

The Australian Consortium for Gravitational Wave Astronomy (ACIGA) in collaboration with LIGO is developing a high optical power research facility at the AIGO site, Gingin, Western Australia. Research at the facility will provide solutions to the problems that advanced gravitational wave detectors will encounter with extremely high optical power. The problems include thermal lensing and parametric instabilities. This article will present the status of the facility and the plan for the future experiments.

Feedback control of thermal lensing in a high optical power cavity

This paper reports automatic compensation of strong thermal lensing in a suspended 80 m optical cavity with sapphire test mass mirrors. Variation of the transmitted beam spot size is used to obtain an error signal to control the heating power applied to the cylindrical surface of an intracavity compensation plate. The negative thermal lens created in the compensation plate compensates the positive thermal lens in the sapphire test mass, which was caused by the absorption of the high intracavity optical power. The results show that feedback control is feasible to compensate the strong thermal lensing expected to occur in advanced laser interferometric gravitational wave detectors. Compensation allows the cavity resonance to be maintained at the fundamental mode, but the long thermal time constant for thermal lensing control in fused silica could cause difficulties with the control of parametric instabilities.

THE AIGO PROJECT

The AIGO project is the proposed southern hemisphere advanced large scale gravitational wave detector. With this southern hemisphere detector, the global array of ground based gravitational wave detectors will be substantially improved. Here we summarize the current plans for the AIGO detector.

Comparison of band-limited RMS of error channel and calibrated strain in LIGO S5 data

Aidan Brooks, David Hosken , Damien Mudge, Jesper Munch and Peter Veitch and are members of the LIGO Scientific CollaborationMany LIGO data analysis pipelines use either the DARM ERR or AS Q channels as the data source and use a response function R(f) generated from time-dependent calibration measurements to convert to strain in the frequency domain. As calibration varies on a timescale of tens of seconds, the response function must be updated frequently. An alternative is to use time-domain calibrated strain h(t). During the recent year-long LIGO science run (S5), preliminary strain data was published alongside raw interferometer output, typically within half an hour of the raw data being produced. As strain data is now available in highly-reduced form within the LIGO data archive, it represents a convenient alternative for LIGO search pipelines. This paper examines a measure of quality for calibrated strain data by calculating the band-limited RMS (BLRMS) difference between h(t) and strain he(t) as calculated directly from DARM ERR in the frequency domain.Many LIGO data analysis pipelines use either the DARM ERR or AS Q channels as the data source and use a response function R(f) generated from time-dependent calibration measurements to convert to strain in the frequency domain. As calibration varies on a timescale of tens of seconds, the response function must be updated frequently. An alternative is to use time-domain calibrated strain h(t). During the recent year-long LIGO science run (S5), preliminary strain data was published alongside raw interferometer output, typically within half an hour of the raw data being produced. As strain data is now available in highly-reduced form within the LIGO data archive, it represents a convenient alternative for LIGO search pipelines. This paper examines a measure of quality for calibrated strain data by calculating the band-limited RMS (BLRMS) difference between h(t) and strain he(t) as calculated directly from DARM ERR in the frequency domain.