To overcome the limitation of the small tuning range of 1.3-µm-wavelength distributed Bragg reflector (DBR) lasers using the carrier-plasma effect, we designed a DBR structure with InAlAs carrier confinement layers and an InGaAlAs core layer. We found that the enhanced carrier density and small effective mass of electrons in the core layer of the DBR regions resulted in a wide Bragg wavelength shift. The enhanced refractive-index change due to the new structure enabled us to fabricate the world's first 1.3-µm-wavelength superstructure-grating DBR laser with a quasi-continuous tuning range of over 30 nm.