A system for producing an output light beam of a given spectrum is provided. The system comprises: a light source; a separator configured to separate an input light beam, from the light source, into a retained light beam directed along a first path and an excess light beam directed along a second path, based on wavelength of the input light beam; an optical power shifter positioned to intercept the excess light beam, the optical power shifter configured to convert the excess light beam into a power-shifted light beam comprising at least some wavelengths and/or power red-shifted relative to the excess light beam; and a combiner positioned to intercept both the retained light beam and the power-shifted light beam, the combiner configured to combine the retained light beam and the power-shifted light beam onto a common path to produce the output light beam.