Simultaneous Photonics Generation of Multiple Chirp Rate Microwave Waveform With Manifold Frequency Multiplying Capability by Using Triple Parallel Mach-Zehnder Modulators

In this paper, the simultaneous generation of single-chirp, un-chirp, and multiple-chirp microwave waveforms with manifold frequency multiplying capability has been experimentally demonstrated through photonic techniques assisted by three parallel Mach-Zehnder modulators (TP-MZM). There is a provision to generate a single chirp signal of a specific chirp rate and centre frequency and multiple chirp signals with desired performance parameters by adjusting biasing voltage only without modifying the original experimental setup. The chirp rate and time- bandwidth product of the generated dual chirp signal are also evaluated concerning the frequency multiplying order. The proposed technique is tunable in frequency, however, the generation of high-frequency microwave signals is limited by the bandwidth and speed of the MZM and photodetector. The novelty of our proposed scheme lies in the fact that in this proposed technique costly hybrid couplers, polarization rotators, multiple photodetectors, bandpass filters etc. are not required. In addition, we are driving MZM-1 and MZM-2 by an un-chirp microwave signal with manifold frequency and MZM-3 by a chirp RF signal with manifold frequency. This technique leads to an increase in the chirp rate manifold without constraints or any limitations. The multi-function radar system tremendously requires a multi-band and multi-chirp signal and the proposed set-up can also be utilized to fulfill the need of both these requirements. Hence the proposed scheme has potential applications in modern chirp radar and surveillance systems. To the best of our knowledge photonic technique based on triple parallel MZI in the context of multi-band and multichirp rate or un-chirp microwave signal without using polarization rotators, multiple photodetectors and hybrid optical couplers has not been studied in the past.