High Power Lasers for Gravitational Wave Interferometry

The international quest to detect gravitational waves and create a radically new form of astronomy, including the LIGO, VIRGO, GEO, TAMA and LCGT projects, is perhaps the most important and exciting current physics project. Success will result in the opening of a completely new window upon the universe, through which one is not restricted to looking at only electromagnetic emission from hot matter.

We are developing high power, single frequency, diffraction limited, solid-state lasers for use in advanced and cryogenic interferometric detectors of gravitational waves. This project is funded by the Australian Research Council (ARC) and is part of the ACIGA (Australian Consortium for Interferometric Astronomy) collaboration. Our international collaborators include the LIGO project (Caltech, MIT, …) and Stanford University in the USA, the French/Italian VIRGO project, and the Lazer Zentrum in Hannover.

Our approach to the development of the laser sources for these projects is to use a chain of injection-locked lasers. We have successfully developed a 10W continuous wave, single frequency, Nd:YAG laser that meets the LIGO I specifications. Our 10W laser is installed at the Japanese TAMA interferometer and at the ACIGA/LIGO High Optical Power Test Facility located at Gingin in WA.

The next stage, a 100W-class laser, uses a novel gain medium architecture that combines the best features of cladding-pumped fibre lasers, waveguide lasers and free-space lasers, and which has recently been patented. It uses a stable-unstable laser resonator, thereby enabling high output power from a compact laser. We have recently demonstrated 104W multi-mode output power with a slope efficiency of 44% and very low wavefront distortion.

For cryogenic interferometry, we are investigating the use of Er:Yb:YAG lasers (wavelength = 1645nm) that use the novel gain medium architecture, and the use of cladding-pumped, large mode area Er:Yb:glass fibre lasers (wavelength = 1550nm).

Damien Mudge and David Hosken: 10W laser installation at TAMA

Personnel

Publications

• Thermally induced birefringence in Nd:YAG slab laser
  Ostermeyer M., Mudge D., Veitch P.J. and Munch J
  Appl. Opt. 45, 5368-5376 (2006)
• Development of power scalable lasers for gravitational wave interferometry
  Hosken D.J., Mudge D., Hollitt C., Takeno K., Veitch P.J., Hamilton M.W and Munch J.
  Progress of Theoretical Physics Supplement 151, 216 - 220 (2003)
• High-power Nd:YAG lasers using stable-unstable resonators
  Mudge D., Ostermeyer M.O., Ottaway D.J., Veitch P.J., Munch J., and Hamilton M.W.
  Classical and Quantum Gravity 19, 1783 - 1792 (2002)