Application of DDS in laser modulation

摘要

Acousto-optic modulator (AOM) and electro-optic modulator (EOM) drived by voltage controlled oscillator (VCO) are widely used to control and modulate laser, especially semiconductor lasers. We designed a frequency generator based on direct digital synthesizer (DDS) technology which can be used to replace VCO. The frequency generator with high frequency stability can reach 160 MHz bandwidth and frequency resolution up to 1 Hz. The output frequency is programmable and controlled by input TTL edge. These advantages are not available with VCO. We obtain a output radio frequency (RF) power as high as 1W with a power amplifier in order to drive an AOM. This device has been used to scan the wavelength of external cavity laser diode (ECLD) in our laser cooling experiments.