  We use a waveguide-based electro-optic phase modulator, driven by a
nanosecond-timescale arbitrary waveform generator, to produce an optical
spectrum with an arbitrary pattern of sidebands. A programmed sequence of
linear voltage ramps, with various slopes, is applied to the modulator. The
resulting phase ramps give rise to sidebands whose frequency offsets relative
to the carrier are equal to the slopes of the corresponding linear phase ramps.
This extension of the serrodyne technique provides multi-line spectra with
sideband spacings in the 100 MHz range.
