Tunable Broadband Mm-Wave Signal Generation based ona Injection Lock of Selected OFC Lines

A novel photonic-based tunable broadband signal generator for millimeter wave (mm-wave) signals is demonstrated. An optical frequency comb (OFC) is employed for optical injection locking (OIL) of two slave lasers with different wavelengths. Due to the high gain filtering function provided by the OIL, two salve lasers within the locking range can be tuned and locked by the selected comb lines of the OFC. In the experiment, a 25-line flattened OFC is generated by cascading Mach-Zehnder modulators (MZMs) with a mode spacing of 2 GHz. The locking range of two slave lasers is measured to be 1.1 GHz as injection ratio of -40 dB, consistent with the simulation. The spur suppression ratios (SSRs) are measured to be 60 dB in a span of 10 MHz. The RF power flatness of generated broadband tunable mm-wave signal is tested to be within 3.84 dB for frequency 2 GHz to 48 GHz.