Switchable circular dichroism resonators for spin selective absorption

The circular dichroism resonator (CDR) can produce spin selective absorption for left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) waves. However, in the microwave band, the previously proposed CDRs only absorb designated CP waves and lack versatility in practical applications. Here, we propose a switchable CDR based on a pair of PIN diodes. It switches between the left-hand and right-hand CDR modes through the alternate ON-OFF of two PIN diodes. The left-hand CDR absorbs LCP waves and converts RCP waves into LCP waves. The opposite is true for the right-hand CDR. The thickness of the switchable CDR is one-tenth of the working wavelength, which is suitable for integrated manufacturing.