A method of minimizing localized heating of, or minimizing signal losses across a source of loss in, an optical fiber used in transmission of a high power optical signal at an operating wavelength. These methods include the steps of: providing an optical fiber which comprises either (i) a coating characterized by an absorbance of less than about 4.5 dB/cm at the operating wavelength or (ii) a refractive index lower than the refractive index of a cladding layer of the optical fiber by more than about 3.times.10.sup.-3 at the operating wavelength, or (iii) both (i) and (ii); and transmitting a optical signal having a power greater than about 250 mW through the optical fiber, wherein the coating, cladding layer, or combination thereof are selected to minimize localized heating of the optical fiber or to result in a signal loss across a source of loss that is less than about 250 mW at the operating wavelength.