A 193 nm ArF excimer laser is used in the photoablation of bulk YBa2Cu3O7 and the oxides of barium, copper and yttrium. Optical emission from the plume of ablated material is studied from 350 to 630 nm. Emission from ions, atoms and diatomic molecular oxides are observed. The effects of applied electric and magnetic fields on the plume in vacuum and oxygen are discussed. The applied electric field is found to enhance the intensity of all the emitting species enabling identification of the highly congested emission lines in the spectra. The results might help to provide a mechanism for the observed effect of an applied electric field in the production of in situ superconducting thin films of YBa2Cu3O7.