Methods and devices for providing a multiwavelength laser which may be used for multicasting and other optical communications uses. The present invention provides a quantum dot based multiwavelength laser with a monolithic gain block. The Fabry--Perot gain block has both upper and lower InP cladding layers. The laser system has a middle quantum dot layer with multiple stacked layers of InAs quantum dots embedded in InGaAsP. When provided with a CW injection current, the laser system produces an output spectra with equally spaced multiple emission peaks. With an input optical data signal applied to the laser system, the laser system duplicates the data in the input signal across multiple different wavelengths.