We report a low-cost manufacturing approach for fabricating monolithic multi-wavelength sources for dense wavelength division multiplexing(DWDM)systems that offers high yield and eliminates crystal regrowth and selective area epi-taxy steps that are essential in traditional fabrication methods.The source integrates an array of distributed feedback(DFB)lasers with a passive coupler and semiconductor optical amplifier(SOA).Ridge waveguide lasers with sampled Bragg side wall gratings have been integrated using quantum well intermixing to achieve a fully functional four-channel DWDM source with 0.8 nm wavelength spacing and residual errors＜0.13 nm.The output power from the SOA is＞10 mW per channel making the source suitable for use in passive optical networks(PONs).We have also investigated using multisection phase-shifted sampled gratings to both increase the effective grating coupling coefficient and precisely control the channel lasing wavelength spa-cing.An 8-channel DFB laser array with 100 GHz channel spacing was demonstrated using a sampled grating with two π-phase-shifted sections in each sampling period.The entire array was fabricated by only a single step of electron beam litho-graphy.