Abstract: An emitter for emitting radiations at a specific wavelength includes a Joule-heated emitting electrical conductor to emit radiations at an emission temperature, a controller to control a variable voltage subjected to the Joule-heated emitting electrical conductor and modulated according to a duty cycle, the duty cycle being variable between a high-average power duty cycle during hot periods, so that the Joule-heated emitting electrical conductor is subjected to a high-average power to reach and maintain the emission temperature; and a low-average power duty cycle during cold periods alternated to the hot periods, so that the Joule-heated emitting electrical conductor is subjected to a low-average power to reach a temperature smaller than the emission temperature, wherein the high-average power duty cycle and the low-average power duty cycle is defined based on a temperature-indicative measured value indicative of the ambient temperature as measured.