Optically tunable split-ring resonators controlled lead sulfide quantum dots modulator for wide THz radiation

It is particularly appealing for efficient active terahertz (THz) modulators using photonic structures to enhance light-matter interaction. Here, an optical controlled THz modulator is proposed that combines lead sulfide (PbS) quantum dots with subwavelength metallic split-ring resonators (SRRs) for providing field enhancement. The modulation depth reaches 60.3%, which is approximately 3 times larger than the PbS quantum dots film without SRRs (as reference) in the frequency range of 0.1-1.1 THz. Such significant enhanced THz modulation is mainly due to the local THz field enhancement caused by the SRRs, which is consistent with the simulation result.