Abstract: An optical-fiber type power transmission device, comprises an optical fiber for transmitting the power from a power input end through a power output end of the optical fiber; an opaque protective sleeve over the optical fiber and having an inner diameter larger than the outer diameter of the optical fiber to define a gas passageway therebetween; and a tubular waveguide secured to the protective sleeve at the power output end of the optical fiber and projecting past the power output end. The tubular waveguide is unattached to the optical fiber to permit the fiber to move with respect to the tubular waveguide and protective sleeve during the bending of the device.