Photon-gated persistent spectral hole-burning

This article reviews recent progress in the area of photon-gated persistent spectral hole-burning, in which one photon selects absorbers in an inhomogeneously broadened line and a second “gating’. photon of a different wavelength completes the excitation necessary to produce a spectral hole. This phenomenon provides a crucial threshold in the hole formation process, allowing reading with the first wavelength alone to be nondestructive. Examples of photon-gating in both inorganic and organic materials are summarized, with emphasis on the organic materials. © 1989 The Japan Society of Applied Physics.