Modulation characteristics of optical frequency shifters based on periodic coupling

The authors compare the performance of frequency shifters based on the interdigitated electrode and the traveling-wave electrode, and find the number of coupling sections required. Instead of using coupled-mode analysis, the authors developed a computer simulation program using matrix multiplications and the fast Fourier transform (FFT). This numerical approach is straightforward and can be applied to different electrode designs. Results indicate that highly single-sideband optical frequency shifters can be realized by as little as one coupling section. Detailed modulation characteristics, effects of the modulation waveform, the number of coupling sections, and the electrode attenuation on the performance of frequency shifters are reported