Controllable broadening of zero-phonon lines by means of the Doppler effect and prospects of using spectral hole burning in optical informatics

Abstract

An attempt is made to extend the spectacular variant of optical informatics efficient at liquid helium temperature—holography based on zero-phonon lines (ZPLs) and spectral hole burning, including time-and-space-domain holography—to higher temperatures, up to room temperature. At room temperature, both optical and Mössbauer narrow ZPLs exist; however, they do not have the inhomogeneous broadening that transforms a ZPL into a broad band, which is necessary for informatics based on light pulses. The idea of producing a band with an appropriate width from narrow ZPLs by using the Doppler effect is advanced. A variant of experimental realization of this idea by means of a scheme with a rotating disk covered by a layer of a material sensitive to spectral hole burning is considered. Numerical estimates were performed for narrow optical ZPLs and for the yet experimentally unconfirmed Mössbauer ZPL in the visible spectral range (dark blue nuclear light) that corresponds to a transition between the two low-lying levels of the ²²⁹Th isomer. For the narrowest optical ZPLs known at present, with a width of about 100 Hz, the estimates give favorable results, in particular, for prospects of realizing a photoelectrically accumulated stimulated photon echo.