Doped fiber amplifiers using rare-earth doping materials with linear and non-linear interactions between the optical signal to be amplified and the pump laser have become a standard element of optical telecommunications systems for multiple applications including for example extending the reach of optical links before opto-electronic conversion is required or support increased fanout. Two shield members on the blower housing prevent the ambient air from mixing with the hot air of the engine. A watermark is embedded by slightly varying various pit locations within the visual design. After the etching, dopant is implanted within the trenches to form a sourcedrain region that extends less than an entirety of the trench width.