Multiband Chirp Microwave Signals Generator With Multiple Chirp Rates Based on Photonic Approach

We report a photonic approach to generate multiband chirp microwave signals with multiple chirp rates based on a polarization-division-multiplexed dual-parallel Mach–Zehnder modulator (PDM-DPMZM). Two sub-DPMZMs are driven by a radio frequency (RF) signal and a baseband single-chirped signal, respectively. The DC biases of the modulator are set appropriately to produce carrier-suppressed double sidebands modulated by the RF signal with almost same amplitudes. Meanwhile, odd-order (or even-order) optical sidebands modulated by the single-chirped signal are realized, while the optical carrier is always suppressed. Therefore, multiband chirp microwave signals with two center frequencies and one and triple (or double and quadruple) the chirp rate of the baseband signal are generated successfully after photodetection. Microwave signals with multiple chirp rates are widely applicated in the electrical domain, while few methods are reported based on the photonic generation. Our demonstrated experiment shows that the obtained multiband dual-chirp signals contain two chirp rates of π × 2 × 10
¹⁴
s
⁻²
and π × 6 × 10
¹⁴
s
⁻²
(or π × 4 × 10
¹⁴
s
⁻²
and π × 8 × 10
¹⁴
s
⁻²
) for the single-chirp signal with chirp rate of π× 2 × 10
¹⁴
s
⁻²
. Large potential applications of our system can be found in the multifunction radar and detection systems.