The Virgo 3 km interferometer for gravitational wave detection

Virgo, designed, constructed and developed by the French–Italian VIRGO collaboration located in Cascina (Pisa, Italy) and aiming to detect gravitational waves, is a ground-based power recycled Michelson interferometer, with 3 km long suspended Fabry–Perot cavities. The first Virgo scientific data-taking started in mid-May 2007, in coincidence with the corresponding LIGO detectors.
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\nThe optical scheme of the interferometer and the various optical techniques used in the experiment, such as the laser source, control, alignment, stabilization and detection strategies are outlined.
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\nThe future upgrades that are planned for Virgo from the optical point of view, especially concerning the evolution of the Virgo laser, are presented.
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\nFinally, the next generation of the gravitational wave detector (advanced Virgo) is introduced from the point of view of the laser system.