Experimental demonstration of broadband Lorentz non-reciprocity in an   integrable photonic architecture based on Mach-Zehnder modulators
  We demonstrate the first active optical isolator and circulator implemented in a linear and reciprocal material platform using commercial Mach-Zehnder modulators. In a proof-of-principle experiment based on single-mode polarization-maintaining fibers, we achieve more than 12.5 dB isolation over an unprecedented 8.7 THz bandwidth at telecommunication wavelengths, with only 9.1 dB total insertion loss. Our architecture provides a practical answer to the challenge of non-reciprocal light routing in photonic integrated circuits. 
Yisu Yang, Christophe Galland, Yang Liu, Kang Tan, Ran Ding, Qi Li,   Keren Burgman, Tom Baehr-Jones and Michael Hochberg
physics.optics