Sub-kHz precision voltage-controlled-oscillator system for laser frequency control

Abstract

A system design is presented which allows a voltage controlled oscillator (VCO) to be tuned to an arbitrary frequency between 78 and 94 MHz with an accuracy better than 1 kHz (10 ppm). The temperature coefficient is on the order of 1 kHz/K, giving a long-term stability better than 1 kHz in a controlled environment. The slew rate for fiequency switching is ≈ 20 MHz in 50 μs. The system comprises a computer-controlled precision voltage source, a spline interpolation of the voltage versus frequency characteristic, and good isolation of the VCO electronics from the subsequent circuitry. It provides an extremely low-cost alternative to frequency synthesisers. In our application involving the launching of slow atoms at a target, we can achieve atomic velocities as low as 10 cm/s with 1 cm/s precision. Show more