Physics / mechanism
InGaAs (indium gallium arsenide) photodiodes are III-V compound semiconductor detectors absorbing light from ~900 nm to 1700 nm (extended InGaAs reaches 2.6 µm by tuning In content). Photons excite electron-hole pairs across a narrow bandgap (~0.75 eV for In₀.₅₃Ga₀.₄₇As lattice-matched to InP); reverse-biased p-i-n or avalanche (APD) structures sweep carriers before recombination. Key parameters: responsivity 0.8–1.1 A/W at 1550 nm, dark current 1–10 nA (p-i-n), noise-equivalent power sub-pW/√Hz, bandwidth up to 40+ GHz for high-speed variants. APD variants achieve multiplication gains of 10–30×. State of the art: wafer-scale InP epitaxy, monolithic arrays for LiDAR and optical coherence tomography, with leading suppliers including Lumentum, II-VI/Coherent, Hamamatsu, and GPD Optoelectronics.
Competitive landscape
Competing detector technologies split by wavelength and application. Ge-on-Si photodiodes are CMOS-compatible and cover 900–1600 nm but carry higher dark current and inferior noise floor. Silicon APDs dominate below 900 nm at lower cost. HgCdTe (MCT) extends to mid-IR but requires cryogenic cooling and is expensive. For LiDAR specifically, SiPM arrays compete on cost and ecosystem maturity at 905 nm.
Companies using
Connected ideas
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Frontier (open questions)
- To be added.