Precise modulation of laser radiation by an acousto-optic modulator for stabilisation of the Nd : YAG laser on optical resonances in molecular iodine

A system of precise frequency modulation of laser radiation by an acousto-optic modulator, which makes it possible to stabilise the radiation power and simultaneously suppress the residual amplitude modulation to a level of 10^-8 of the total laser power at the third harmonic of modulation frequency (∼500 Hz), is presented. The use of this system for the Nd : YAG/I₂ optical frequency standard and application of digital signal synthesis and processing methods provided a level of frequency standard instability as small as ∼10^-15 for ∼6 × 10⁴ s. (frequency standards)