The background art discussed in this section includes information disclosed under 37 CFR §1.97 and §1.98.
The performance of current directional measurement instruments, such as network analyzers, is inadequate for many possible applications that extend significantly above one hundred gigahertz. Existing and proposed directional measurement systems that form the cores of directional measurement instruments suffer from limited directivity or bandwidth at frequencies above one hundred gigahertz.
A lightwave is modulated by a modulation wave in an optical modulator. The modulation wave is often in the form of a radio wave, microwave, or millimeter wave and guided by a modulation waveguide of the optical modulator. A travelling-wave optical modulator may be employed in an optical system having modulation in the microwave or millimeter-wave frequency range. In a travelling-wave optical modulator, the modulation wave is substantially coherent with the lightwave modulation over the length of the modulator, and operation is said to be phase-matched.