Photonic generation of phase-coded millimeter-wave signal using a polarization modulator

A novel approach to generating phase-coded millimeter-wave (mm-wave) signal in the optical domain is proposed. In the proposed system, a radio frequency signal is applied to a Mach-Zehnder modulator that is biased at the minimum transmission point to generate two optical sidebands with suppressed carrier. A differential group delay device is utilized to rotate the polarization states of the optical sidebands to ensure they are orthogonally polarized. The two sidebands are then sent to a polarization modulator (PoIM), with their polarization directions aligned with the two principal axes of the PoIM, to achieve phase coding. A 33-GHz mm-wave signal that is phase coded by an 8.28 Gb/s digital sequence is experimentally demonstrated. The approach has potential applications in mm-wave pulse compression radar and wireless communications.