Reduction of laser intensity noise over 1 MHz band for single-atom trapping

Low noise lasers are required in a variety of scientific applications including optical communication, quantum key distribution, and atom trapping. We present a general scheme for broadband noise reduction up to 1 MHz with a large dynamic range by directly acting on the laser beam. We reduce the intensity noise of a high-power 671nm laser beam from a sum-frequency generation (SFG) setup by using an electro-optic modulator (EOM) and acousto-optic modulator (AOM) in series. The EOM reduces noise at high frequency (10 kHz to 1 MHz), while the AOM sets the average power of the light and reduces noise at low frequency (up to 10 kHz). The light is then used to trap single sodium atoms in an optical tweezer, where the lifetime of the atoms is limited by parametric heating due to laser noise at twice the trapping frequency. With our noise eater, the noise is reduced by up to 15 dB at these frequencies and the lifetime of the atom in the optical tweezer is increased by an order of magnitude to around 6 seconds, which is favorable in the future applications of quantum information and simulation with neutral atom tweezer arrays.