Physics / mechanism
Photonic memory stores and retrieves data using light rather than electrons, exploiting phase-change materials (PCMs) or electro-optic effects in integrated photonic circuits. The dominant mechanism: GST (Ge₂Sb₂Te₅) or GSST thin films erase/write via laser pulses that toggle crystalline ↔ amorphous states, modulating optical transmission. Multi-level cell (MLC) operation demonstrated at 5+ levels per cell. On-chip read speeds reach sub-nanosecond. But note: AIMA — the only memory-medium company in the space — does NOT use phase-change; it uses femtosecond all-optical magnetic switching (see landscape below). Leading academic demonstrations: Oxford/Münster (Bhaskaran/Pernice, PCM-on-waveguide origin), MIT, EPFL, NTT (all-optical RAM). Commercial activity nascent. Integration with silicon-photonics waveguides is the active frontier; insertion loss and CMOS back-end compatibility remain unsolved at volume.
Company landscape (2026)
Honest headline (landscape sweep, 2026-05-30): very few pure-play “memory built from light” companies exist. Most “photonic + memory” is actually interconnect, compute, or archival storage. The genuine memory-medium plays:
These three are the genuine memory-medium attempts (AIMA most advanced; the latter two found via a 2026-05-30 Granola search). The rest of the category is lab work (TU Eindhoven/Koopmans, Radboud/Kimel-Rasing, MIT/EPFL/NTT).
Optical / holographic ARCHIVAL storage (separate market: cold-storage, not in-package AI memory)
Real, funded, EU-concentrated: Cerabyte (DE — ceramic-glass; WD / Pure / In-Q-Tel backed), SPhotonix (CH — 5D silica glass, $4.5M), HoloMem (UK — holographic tape), Ewigbyte (DE — glass ablation), Optera Data (SG). Defunct ref: Akonia Holographics (US) — acquired by Apple (2018) for AR waveguides.
Research / lab context (not companies)
Microsoft Project Silica (5D glass archival), IBM (non-volatile optical memory in SiPh), Oxford/Münster (PCM-on-waveguide origin), NTT (all-optical RAM nanocavity), Southampton (Sb₂Se₃ low-loss PCM + the Kazansky 5D-glass lineage).
Companies using
Connected ideas
Sources
Frontier (open questions)
- Does any photonic / optical memory reach high-volume manufacturing this decade?
- Which pull comes first for photonic memory, compute buffering or interconnect?