We demonstrate a tunable laser consisting of two gain sections with different bandgap energies using selective intermixing of InGaAsP multiple quantum wells. The selectivity in the intermixing process is achieved using different capping films during a high-temperature rapid annealing process. The region that was capped by a SiOyNx film had its bandgap energy blueshifted to 1530 nm while the region that was capped by a SiNx film had its bandgap energy unchanged at 1560 nm. Wavelength tuning is achieved by injecting current separately into the two gain sections. When the currents injected into the two sections are varied, the combination of the gain spectra leads to a laser wavelength in the overall effective gain whose peak position depends on the magnitudes of the two injected currents. The fabricated device was capable of producing laser emission that was tunable from 1538 to 1578 nm with almost constant output power from 1544 to 1566 nm.