Dynamic complex amplitude modulation with active metasurfaces

Min Seok Jang^1*

¹School of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea

* Presenter:Min Seok Jang, email:jang.minseok@kaist.ac.kr

Achieving independent control of the phase and amplitude of light with extreme spatiotemporal resolution is a key challenge in nanophotonics. Significant advancements have been made in reflection-type metasurfaces, where the transmission channel is blocked, and input-output beams share the same port. However, in transmission configurations, active modulation of complex amplitude remains unsolved. This work presents a systematic method to realize phase-only transmission modulation using a single optical resonance. We demonstrate that in a standard two-port setup, phase modulation greater than π is not possible with a single resonance. By introducing additional ports, such as non-specular diffraction channels, this limitation can be overcome. Our theoretical analysis shows that the maximum transmittance for phase-only modulation with a single resonance is 25%. Furthermore, we provide an example metasurface device structure based on Ge and LNO.

Keywords: Metasurfaces, Optical resonance, Electro optic effect, Complex amplitude modulation, Dynamic phase tuning