Performances of Microwave Photonic Notch Filter Based on Microring Resonator With Dual-Drive Modulator

A tunable microwave photonic notch filter with ultrahigh radio frequency (RF) rejection ratio is achieved by using a dual-drive Mach-Zender modulator and a microring resonator. In addition, we dedicated to clarify the mechanisms of the microwave photonic notch filters based on a microring resonator under both overcoupled and undercoupled states and the performance differences between these two situations are investigated in detail. Furthermore, the experimental results show that the cancellation microwave photonic notch filter with ultrahigh RF rejection ratio can be achieved with both undercoupled and overcoupled microring resonators. Besides, an RF rejection ratio exceeding 50 dB was achieved for a microring resonator with an optical extinction ratio of only 4 dB, where a 46-dB enhancement from optical to RF response is obtained. Also, the bandwidth of the microwave photonic filter can tuned from 0.65 to 2.2 GHz by adjusting the coupling ratio of the ring resonator. Meanwhile, by tuning the wavelength of the optical carrier, the filtering frequency can be tuned and a tuning range of about 25 GHz was achieved. The implementation is much simpler and more economical compared with previous reports and has great potential in monolithic integration of microwave photonic filters on chip.