<p>A semiconductor radiation source comprises an active core structure comprising a semiconductor material, at least one microheater positioned above the active core structure in thermal communication with the active core structure, and at least a first electrode positioned on a side of the microheater in electrical communication with the active core structure for injecting current into the active core structure to control the current density in the active core structure. Methods of operation of the source to provide tuning of the output wavelength are also disclosed.</p>
