An optical apparatus comprising an optical source for providing output light for providing input signal light can comprise a pump source for pumping a four wave mixing (FWM) process with light pulses (“FWM pump light”); a FWM element in optical communication with said pump source, said FWM element configured for hosting the FWM process to generate, responsive to the FWM pump light, pulses of FWM signal light and FWM idler light having different wavelengths; and a laser or amplifier optical device comprising a gain material for providing optical gain at a gain wavelength via a process of stimulated emission responsive to optical pumping with pump light, said laser or amplifier optical device in optical communication with said optical source and receiving one of the FWM signal light and the FWM idler light as input signal light having the gain wavelength for optically seeding with input signal light the laser or amplifier optical device.