Physics / mechanism
Heterogeneous photonic integration combines dissimilar material platforms—typically III-V (InP, GaAs, GaN) active layers bonded or epitaxially grown onto silicon or silicon nitride passive waveguide circuits—to co-locate light generation, amplification, modulation, and detection on a single chip. The mechanism relies on evanescent coupling or butt-coupling between the gain medium and low-loss passive waveguide after direct wafer bonding or die-to-wafer bonding. Key figures of merit: coupling efficiency >90%, on-chip laser threshold currents <5 mA, propagation loss <0.5 dB/cm in SiN, and co-integration with germanium photodetectors at >50 GHz bandwidth. State of the art: Intel, Marvell (via Inphi), and imec-led consortia ship heterogeneous silicon photonic transceivers at 400G–800G; research labs demonstrate 1.6T co-packaged optics using this architecture.
Competitive landscape
Monolithic III-V photonics (InP PICs) competes on performance but loses on cost and CMOS fab compatibility. Silicon-only photonics lacks gain entirely. Thin-film lithium niobate (TFLN) competes on modulation bandwidth (>100 GHz EO) but still needs an external laser. Quantum dot on silicon is an emerging monolithic alternative, avoiding bonding steps at the cost of yield immaturity.
Investment relevance (vehicle-agnostic)
| Approach | Gain on-chip | CMOS compatible | Modulation BW |
|---|---|---|---|
| Heterogeneous III-V/Si | Yes | Partial | ~50 GHz |
| Monolithic InP | Yes | No | ~100 GHz |
| TFLN + external laser | No | No | >100 GHz |