Photonic Generation of Phase-Coded Millimeter-Wave Signal With Large Frequency Tunability Using a Polarization-Maintaining Fiber Bragg Grating

A photonic approach to generating a phase-coded millimeter-wave (mm-wave) signal with large frequency tunability is proposed and demonstrated. Two ± second-order optical sidebands are generated by using a Mach-Zehnder modulator that is biased at the maximum transmission point and an optical notch filter. A polarization-maintaining fiber Bragg grating is then utilized to make the two sidebands orthogonally polarized. By sending the two orthogonally polarized sidebands to a polarization modulator, to which a phase-coding signal is applied, a frequency-quadrupled phase-coded mm-wave signal is generated. The generation of a phase-coded mm-wave signal with tunable frequencies at 40, 42, and 50 GHz is experimentally demonstrated. A pulse compression ratio of about 128 is achieved.