Abstract: A multisection quantum dot laser (7) comprising at least first (8) and second (9) sections, each section (8, 9) comprising a semiconductor substrate (2) comprising p (3) and n type (4) layers and a quantum dot layer sandwiched therebetween; the semiconductor substrate (2) comprising a back electrical contact in electrical contact with one of the p and n type layers and a tuning electrical contact (13, 14) in electrical contact with the other of the p and n type layers; the quantum-dot layers of the first (10) and second (11) sections being portions of the same quantum dot layer (12) forming a laser cavity.