A device comprising: a support structure; and at least two lasers (102, 104) on the support structure, each including: a semiconductor structure (112, 114) that emits light in response to stimulation; the semiconductor structures of a subset of two or more of the lasers (102, 104) including the same semiconductor material and having substantially the same geometry; and a current flow structure (116, 118) that affects current flow through the laser's semiconductor structure; wherein the current flow structure (116, 118) affects the operating temperature of the laser's semiconductor structure (112, 114); and the current flow structures of a pair of lasers (102, 104) in the subset are differently structured to affect wavelengths of light emitted from the semiconductor structures (112, 114) of the pair of lasers (102, 104) as a result of the different operating temperatures of the semiconductor structures (112, 114) of the pair of lasers (102, 104); characterized in that: the current flow structures (116, 118) of the pair (102, 104) of lasers in the subset differ in at least one of a thickness of an electrode along at least a part of a length of a laser stripe (112, 114) of the respective laser (102, 104), an electrode material and the presence of a non-electrode thermal conducting material along at least a part of the length of the laser stripe (112, 114) of the laser (102, 104) for providing a different thermal resistance. a support structure; and at least two lasers (102, 104) on the support structure, each including: a semiconductor structure (112, 114) that emits light in response to stimulation; the semiconductor structures of a subset of two or more of the lasers (102, 104) including the same semiconductor material and having substantially the same geometry; and a current flow structure (116, 118) that affects current flow through the laser's semiconductor structure; wherein the current flow structure (116, 118) affects the operating temperature of the laser's semiconductor structure (112, 114); and the current flow structures of a pair of lasers (102, 104) in the subset are differently structured to affect wavelengths of light emitted from the semiconductor structures (112, 114) of the pair of lasers (102, 104) as a result of the different operating temperatures of the semiconductor structures (112, 114) of the pair of lasers (102, 104); characterized in that: the current flow structures (116, 118) of the pair (102, 104) of lasers in the subset differ in at least one of a thickness of an electrode along at least a part of a length of a laser stripe (112, 114) of the respective laser (102, 104), an electrode material and the presence of a non-electrode thermal conducting material along at least a part of the length of the laser stripe (112, 114) of the laser (102, 104) for providing a different thermal resistance. a semiconductor structure (112, 114) that emits light in response to stimulation; the semiconductor structures of a subset of two or more of the lasers (102, 104) including the same semiconductor material and having substantially the same geometry; and a current flow structure (116, 118) that affects current flow through the laser's semiconductor structure; wherein the current flow structure (116, 118) affects the operating temperature of the laser's semiconductor structure (112, 114); and the current flow structures of a pair of lasers (102, 104) in the subset are differently structured to affect wavelengths of light emitted from the semiconductor structures (112, 114) of the pair of lasers (102, 104) as a result of the different operating temperatures of the semiconductor structures (112, 114) of the pair of lasers (102, 104); characterized in that: the current flow structures (116, 118) of the pair (102, 104) of lasers in the subset differ in at least one of a thickness of an electrode along at least a part of a length of a laser stripe (112, 114) of the respective laser (102, 104), an electrode material and the presence of a non-electrode thermal conducting material along at least a part of the length of the laser stripe (112, 114) of the laser (102, 104) for providing a different thermal resistance. the current flow structures (116, 118) of the pair (102, 104) of lasers in the subset differ in at least one of a thickness of an electrode along at least a part of a length of a laser stripe (112, 114) of the respective laser (102, 104), an electrode material and the presence of a non-electrode thermal conducting material along at least a part of the length of the laser stripe (112, 114) of the laser (102, 104) for providing a different thermal resistance.