Physics / mechanism
A Mach-Zehnder Modulator (MZM) splits an optical carrier into two arms, applies a phase shift in one or both arms via an electro-optic effect, then recombines them—constructive or destructive interference encodes data onto the light. In silicon photonics, phase shift is achieved by carrier depletion in a PN junction (plasma dispersion effect); in lithium niobate (LN) or indium phosphide (InP), via the Pockels effect. Key parameters: Vπ·L (drive voltage-length product, target <1 V·cm in thin-film LN), extinction ratio (>30 dB desirable), insertion loss, and electro-optic bandwidth. State of the art: thin-film LN (TFLN) MZMs demonstrate >100 GHz EO bandwidth, Vπ <2 V; silicon PIC MZMs run 50–70 GHz with higher Vπ (~5 V), dominant in data-centre transceivers at 400G/800G.
Competitive landscape
| Modulator type | EO bandwidth | Vπ (typ.) | CMOS integration |
|---|---|---|---|
| Silicon PN-junction MZM | 50–70 GHz | ~5 V | Monolithic |
| Thin-film LiNbO₃ MZM | >100 GHz | 1–2 V | Heterogeneous bonding |
| InP MZM | 80–100 GHz | ~2 V | III-V foundry only |
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.