Optically Controlled Multiresonator for Passive Chipless Tag

Abstract

In this letter, an optically controlled passive multiresonator for chipless tag design of radio frequency identification systems operating in UHF range frequency is presented. The proposed multiresonator is composed of three resonators with only $8.9\,\, \text {mm} \times 5.4$ mm overall size, and its ID states are controlled by an optical switch fixed in a 0.3-mm gap. The silicon optical switch can change its electrical state from semiconductor to a near-conducting state when properly illuminated by a laser source. This principle is applied to control the resonator operating frequency and, consequently, the tag ID. The multiresonator is numerically and experimentally evaluated for its both ID states, i.e., 0 and 1 states. The optical switch was illuminated by a laser source at 980 nm with 17 mW of output power. Comparisons between simulated and measured S-parameters show a strong correlation for 0 and 1 ID states, validating the proposed optically controlled passive multiresonator for chipless tag. The power level transition between logic states 0 to 1 is, approximately, 4.8 dB for both simulation and measured results. This proposal has great potential applications for printed light sensors.