Reconfigurable RF Multiband Filter With Widely Tunable Passbands Based on Cascaded Optical Interferometric Filters

Despite the increasing importance and critical needs, reconfigurable radio frequency (RF) multiband filters are currently underdeveloped even both RF electronics and photonics technologies are being explored. Although RF multiband filters with large numbers of simultaneous passbands and wide frequency tuning range are extremely desired, achieving such functionality is extremely challenging. In this paper, a photonics-based highly tunable and reconfigurable RF multiband filter is proposed through the combination of a special designed tunable Mach-Zehnder interferometer and a reconfigurable Lyot loop filter. Both the passband frequencies and the number of simultaneous passbands are adjustable, that one or multiple passbands are continuously tuned over a 20 GHz frequency range, and the number of simultaneous passbands is reconfigurable from zero to seven. As a result, the proposed RF multiband filter can be configured with various passband combinations through the same setup, providing exceptional operation flexibility. Furthermore, broadband operation and excellent filter selectivity are obtained, with sharp passband profiles and over 35-dB sidelobe suppression.