Absolute frequency measurement of an I2 stabilized Nd:YAG optical frequency standard

The frequency of an 1, stabilized Nd:YAG optical frequency standard, developed at the BNM-INM as a national standard for the 'mise en pratique' of the definition of the metre, has been measured with a frequency measurement chain based on a femtosecond laser. A frequency (in-)stability of 2.5 x 10(-13)tau(-1/2) has been measured in the optical domain against a hydrogen maser. The measured (in-)stability decreases to 1 x 10(-14) Without evidence of flicker floor.