We present recent advances in multi-wavelength, power-equalized laser sources that incorporate a semiconductor optical amplifier (SOA) and simple optical filters, such as Lyot-type and Fabry-Perot, for comb generation. Both linear and ring-cavity configurations are presented, and single-pass optical feedback technique is proposed to improve the performance in terms of the number of simultaneously oscillating lines and output channel power equalization. This technique resulted in a broadened oscillating spectrum of 52 lines spaced at 50 GHz, power-equalized within 0.3 dB. Finally, a simplified version that uses only an uncoated SOA for both gain and comb generation is demonstrated.