Performance Improvement of Optically Controlled Microwave Switch by Introducing Complementary Split-Ring Resonator

An optically controlled microwave switch (OCMS) with improved performance is demonstrated by introducing a complementary split-ring resonator (CSRR). The CSRR is etched in the metal ground and placed just below the microstrip gap that is bridged by a piece of high-resistivity silicon dice. Thanks to the deep transmission zero offered by the CSRR, high isolation in the off state can be achieved by controlling the position of transmission zero of the CSRR. Meanwhile, the microstrip gap is allowed to be designed with smaller size for reducing the insertion loss of the OCMS in its on state. Measurements are performed for comparison between the traditional OCMS and the proposed one. The comparison illustrates that the CSRR is an attractive method to improve the performance of the OCMS, with which a reduction of the insertion loss in the on state and an increase of the isolation in the off state are achieved.