Polarization spectroscopy was used to detect persistent spectral holes photochem. burned into the electronic absorption band of a guest mol. in an amorphous host. Tetraphenylporphin doped into a PMMA matrix was studied as an example. The polarization technique improved the contrast ratio (increase of intensity at the hole over background) by a factor of >200. Applications to fast readout of optical memories and line-narrowing spectroscopy are discussed