  High-density communication through optical fiber is made possible by
Wavelength Division Multiplexing, which is the simultaneous transmission of
many discrete signals at different optical frequencies. Vast quantities of data
may be transmitted without interference using this scheme but flexible routing
of these signals requires an electronic middle step, carrying a cost in
latency. We present a technique for frequency conversion across the entire WDM
spectrum with a single device, which removes this latency cost. Using an
optical waveguide in lithium niobate and two infrared pump beams, we show how
to maximize conversion efficiency between arbitrary frequencies by analyzing
the role of dispersion in cascaded nonlinear processes. The technique is
presented generally and may be applied to any suitable nonlinear material or
platform, and to classical or quantum optical signals.
