Physics / mechanism
Indium phosphide (InP) is a III-V direct-bandgap semiconductor (Eg ≈ 1.34 eV) with electron mobility ~5,400 cm²/V·s — roughly 4× silicon. That mobility, combined with a native electro-optic response and gain at telecom wavelengths (1310/1550 nm), makes InP the dominant substrate for monolithically integrated photonic ICs: lasers, modulators, photodetectors, and amplifiers on a single die. State-of-the-art InP PICs achieve modulation bandwidths >100 GHz, wall-plug efficiencies of 20–30% for DFB lasers, and integration densities reaching hundreds of components per chip. Wafer diameter has moved to 4” mainstream, 6” emerging. Key fabs: SMART Photonics, Fraunhofer HHI, WIN Semiconductors.
Competitive landscape
InP’s primary competition is silicon photonics (SiPh), which benefits from CMOS fab scale but cannot lase natively, requiring hybrid/heterogeneous bonding — adding cost and yield risk. Silicon nitride (SiN) dominates low-loss passive routing but has no active gain. Lithium niobate on insulator (LNOI) offers superior electro-optic coefficients (r33 ~30 pm/V) for pure modulation. GaAs covers 850 nm datacenter VCSELs but loses ground above 1 µm.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.