a set of two or more reflective gain media (RGMs), wherein each RGM in the set comprises an active gain medium coupled to an associated reflector;

a set of ring filters organized into a cascaded array;

a set of intermediate waveguides, wherein each intermediate waveguide in the set is coupled to an RGM in the set of RGMs, and channels light from the RGM in proximity to an associated ring filter in the set of ring filters to cause optically coupled light to circulate in the associated ring filter;

a shared waveguide located in proximity to the set of ring filters, so that light circulating in each ring filter in the set of ring filters causes optically coupled light to flow in the shared waveguide;

a shared loop mirror coupled to the shared waveguide; and

an output waveguide, which is optically coupled to the shared loop mirror, wherein the output waveguide includes a broadband modulator that modulates an optical signal based on an electrical input signal;

wherein each RGM in the set of RGMs forms a lasing cavity, which includes an associated intermediate waveguide in the set of intermediate waveguides, an associated ring filter in the set of ring filters, the shared waveguide and the shared loop mirror, wherein each lasing cavity has a different wavelength, which is associated with a resonance of the associated ring filter.