1. a Department of Materials , University of California , Santa Barbara, CA, 93106, U.S.A.
2. b USAF Phillips Laboratory , OLAC PL/RKFE, 10 E. Saturn Blvd., Edwards AFB, CA, 93524-7680, U.S.A.
3. c AT&T Bell Laboratories , Murray Hill, NJ, 07974-9636, U.S.A.