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.