Abstract: An apparatus for generating at least three visible light beams of different output wavelengths for display purposes includes a passively mode-locked solid-state thin-disk laser and a device, including an optical parametric oscillator (OPO) for at least partially converting the primary light beam into electromagnetic radiation having the at least three different output wavelengths. The OPO is preferably an optical fiber feedback OPO. An optical fiber feedback OPO includes a nonlinear optical element and feedback device for feeding back at least a portion of the radiation emitted by the nonlinear medium to the nonlinear element. The feedback device includes an optical fiber.