2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147467A single band in a spatially periodic system splits into a series of quasienergy subbands under the action of DC--AC electric fields. These dynamic fractional Stark ladders should be observable in an investigation of optical absorption.12pages, TeX, 3 figures upon request. This version of the paper was resubmitted to PRL on 3/27/94. This is a structural revision and does not contain any major conceptual changesCondensed Mattertext