There is provided a thermal sensing fiber including a semiconducting element having a fiber length and characterized by a bandgap energy corresponding to a selected operational temperature range for the fiber in which there can be produced a change in thermally-excited electronic charge carrier population in the semiconducting element in response to a temperature change in the selected temperature range. At least one pair of conducting electrodes is provided in contact with the semiconducting element along the fiber length, and an insulator is provided along the fiber length.