Physics / mechanism
Pockels modulators exploit the linear electro-optic (Pockels) effect: an applied electric field induces a refractive index change proportional to field strength, shifting the phase of transmitted light. Configured in a Mach-Zehnder interferometer, phase shift converts to amplitude modulation. Key figure of merit is Vπ·L (half-wave voltage × electrode length); best-in-class thin-film lithium niobate (TFLN) on insulator hits Vπ·L < 2 V·cm with electro-optic bandwidths exceeding 100 GHz and on-chip insertion loss < 3 dB. Competing material platforms include BTO (barium titanate, r₄₂ ~1000 pm/V but integration complexity) and organic EO polymers (r₃₃ up to 300 pm/V, thermal stability issues). TFLN is currently the commercially dominant waveguide platform for hyperscale coherent interconnects and microwave photonics.
Competitive landscape
Incumbent silicon photonics plasma-dispersion modulators operate at Vπ·L ~20 V·cm with bandwidths typically < 50 GHz and introduce free-carrier absorption loss. III-V (InP) modulators offer monolithic integration with lasers but at higher cost and lower yield. Germanium EAMs are compact but bandwidth-limited and lossy.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.