A thin-film organic laser, that includes: a substrate; a bottom mirror provided on the substrate; at least one active region deposited on the bottom mirror, wherein the at least one active region includes organic gain material; an external mirror provided at a predetermined distance from the at least one active region such that the bottom mirror combined with the external mirror forms a laser resonator; and an optical pumping means for exciting the organic gain material to produce a laser beam with a wavelength .lamda. and at least one lateral laser mode in the laser resonator and an output of laser light.