A tuneable laser assembly includes a substrate having formed thereon a plurality of tuneable lasers, waveguides, an optical coupler and an optical amplifier. The lasers have active sections and distributed Bragg reflector (DBR) tuning sections and are characterised by respective emission wavelengths and tuning ranges such that the laser assembly can be tuned over a quasi-continuous predetermined wavelength range. The DBR tuning sections have a length in the range of about 150-200 um, are of the same optical waveguide of the waveguides, a grating strength (KL) less than about 0,5 and a high reflective (HR) coated back facet enhancing the external quantum efficiency from each said tuning sections. The active sections have a length in the range of about 250-300 um comprised of a high-gain/low-loss multi quantum well (MQW) material. The lasers have a total DBR array length of about 500 um.