  We demonstrate a narrow-linewidth 780 nm laser system with up to 40 W power
and a frequency modulation bandwidth of 230 MHz. Efficient overlap on nonlinear
optical elements combines two pairs of phase-locked frequency components into a
single beam. Serrodyne modulation with a high-quality sawtooth waveform is used
to perform frequency shifts with > 96.5 % efficiency over tens of MHz. This
system enables next-generation atom interferometry by delivering simultaneous,
Stark-shift-compensated dual beam splitters while minimizing spontaneous
emission.
