A new fiber pigtailed optical receiver design using a single gradient-index rod lens with a beveled exit face achieved a broadband optical return loss of > 65 dB, which was limited by the diffuse reflection from the photodetector front surface. By contrast the optical return loss for a receiver with an unbeveled lens exit face and an on-axis optical path was limited to a smaller value by the specular reflection from the lens exit face.
© 1992 Optical Society of America
David M. Braun and Wayne V. Sorin, "Optical receiver design for high optical return loss," Appl. Opt. 31, 5237-5240 (1992)