[1] Korea Adv Inst Sci & Technol, Elect Engn, Taejon 305701, South Korea
[2] Acacia, Maynard, MA 01754 USA
[3] JDSU, R&D, Bloomfield, CT 06002 USA
[4] Verizon Technol, Waltham, MA 02451 USA
[5] Nagoya Univ, EECS, Nagoya, Aichi 4648603, Japan
[6] AT&T, Middletown, NJ 07748 USA