Jurgis Viščakas (born 18.04.1927) is a Soviet experimental physicist and an academician of the Academy of Sciences of the Lithuanian SSR (1976). He was born in Vilnius. He graduated from Vilnius University (1950), where he has worked since 1946 (head of a department in 1960—70 and professor from 1977), and from 1977 he has been director of the Institute of Physics of the Academy of Sciences of the Lithuanian SSR.
His research concerned semiconductor physics and laser spectroscopy, in particular the study of nonequilibrium processes in the picosecond range. He studied the kinetics of the nonequilibrium concentration of carriers in the case of several types of local level, under weak and under very intense excitation. He established that irradiation with powerful pulses of laser radiation gives rise to a new channel of recombination through exciton states. He detected and explained generation-recombination effects controlled by an electric field in polymer substances. He studied experimentally the formation of the latent electrophotographic image and developed a theory of it.
State Prize of the Lithuanian SSR (1970). Honoured Worker of Science of the Lithuanian SSR (1977).