In the present study, a broadly fast fi ne single-mode (7 cm 1 ,1.5 nm, 210 GHz) and coarse double-mode (120 nm) wavelength-tunable diode laser system on a thermoelectric cooler (TEC) with double-Littrow external cavity feedback is demonstrated. In our ECL setup, two wavelengths are simultaneously emitted in a spectral range between 1470 nm and 1590 nm. The main advantage of our system is that both modes can be tuned independently. The fast scanning (up to 0.5 kHz) and fi ne tuning(over 7 cm 1 ) are performed by piezo control of the externalcavity length. In the present system, the double-mode operation or fast fi ne tuning properties can be used depending on requirements. These features can make our external cavity double-mode system favourable for many important applications as above mentioned.