DYNAMIC FRACTIONAL STARK LADDERS IN DC-AC FIELDS

A single band in a spatially periodic system splits into a series of q uasienergy subbands under the action of dc-ac electric fields. These d ynamic fractional Stark ladders should be observable in an investigati on of optical absorption. The dependence of the quasienergy spectrum o n a parameter called the electric matching ratio is presented as an el ectric analogue of the well known Hofstadter spectrum.