A new monolithically integrated opto-electronic device has been developed for fast wavelength switching in photonic packet switching. The integrated device, called a tunable duplex integrated light source comprises two distributed Bragg reflector lasers (DBR-LD's), two electroabsorption optical switches, a Y-shaped waveguide coupler, an electroabsorption modulator, and two thermal drift compensators (TDC's). The tuning range of the DBR-LD's is 3 nm, and the wavelength switching time of the optical switches is estimated to be 60 ps including a 50 ps rise time for the electrical pulse generator. The wavelength of a 10 Gb/s NRZ-modulated optical signal is switched without bit loss. Thermal crosstalk between the DBR-LD's, and wavelength drift of the DBR-LD's, which is due to a thermal transient, are effectively suppressed by thermal-drift-compensation operation using the TDC's.