Rotational sensitivity of the G-Pisa gyrolaser

G-Pisa is an experiment investigating the possibility of operating a high-sensitivity laser gyroscope with area less than 1 m2 for improving the performances of the mirrors suspensions of the gravitational wave antenna Virgo. The experimental set-up consists of a He-Ne ring laser with a 4-mirror square cavity. The laser is pumped by an RF discharge where the RF oscillator includes the laser plasma to reach a better stability. The contrast of the Sagnac fringes is typically above 50% and a stable regime has been reached with the laser operating in either single mode or multimode. The effect of hydrogen contamination on the laser was also checked. A low-frequency sensitivity, below 1 Hz, in the range of 10(-8)(rad/s)/square root(Hz) has been measured.