KCl:K crystals including potassium colloids of some hundred angstroms in diameter, prepared by thermal treating, are capable of highly efficient holographic storage with He-Ne laser as a writing and reading light source.
© 1978 Optical Society of America
Mladen Gros, "KCl:K prepared for highly efficient holographic storage," J. Opt. Soc. Am. 67, 1691-1692 (1977)