Wideband Radar Signal Distribution With an Idler-Free Photonic Microwave Frequency Shifter

We demonstrate a novel scheme that combines photonic microwave frequency conversion and fiber transmission to achieve millimeter-wave (mm-wave) wideband radar signal generation and distribution for distributed radar systems. The principle is based on optical carrier-suppressed single-sideband modulation with an integrated polarization-division multiplexing dual-parallel Mach-Zehnder modulator. The idler frequencies in photonic microwave mixing are eliminated by controlling the modulator biases. And the fiber dispersion induced microwave power fading problem related with traditional double-sideband modulation is effectively avoided. The microwave phase distortions induced in the optical and electrical domains are investigated and compensated with electrical pre-distortion. Generation of an mm-wave wideband radar signal at a center frequency of 34.5 GHz with the bandwidth of 9 GHz and its transmission over a 40.8-km single-mode fiber with negligible degradation in pulse compression performance is achieved.