information:filtering, structural:expansion, structural:reformatting, information:extraction
Fourth-generation

The following formats go beyond the current third-generation discs and have the potential to hold more than one terabyte (1 TB) of data and at least some are meant for cold data storage in data centers:

Announced but not released:

In 2004, development of the Holographic Versatile Disc (HVD) commenced, which promised the storage of several terabytes of data per disc. However, development stagnated towards the late 2000s due to lack of funding.

In 2006, it was reported that Japanese researchers developed ultraviolet ray lasers with a wavelength of 210 nanometers, which would enable a higher bit density than Blu-ray discs. As of 2022, no updates on that project have been reported.

Folio Photonics is planning to release high-capacity discs in 2024 with the cost of $5 per TB, with a roadmap to $1 per TB, using 80% less power than HDD.