Optical nonreciprocity via transmissive time-modulated metasurfaces

Area of Science:

• Photonics and Metamaterials
• Nonlinear Optics
• Optical Engineering

Background:

• Time-modulated metasurfaces exhibit frequency mixing due to temporal photonic transitions.
• Nonreciprocity is crucial for optical device functionality, but challenging to achieve in the near-infrared (NIR).

Purpose of the Study:

• To demonstrate nonreciprocal optical responses in the NIR regime.
• To explore the combination of temporal modulation and static high-Q metasurfaces for achieving nonreciprocity.
• To investigate the impact of operating wavelength and modulation frequency on power isolation.

Main Methods:

• Designing a temporal metasurface for frequency up-conversion to the first higher-order harmonic.
• Implementing a static high-Q metasurface for filtering incident frequencies.
• Analyzing signal transmission in forward and time-reversed directions.

Main Results:

• Achieved distinct optical responses in opposite directions, indicating nonreciprocity.
• Demonstrated power isolation levels reaching -30 dB with optimized parameters.
• Showcased the first pure temporal modulation approach for NIR nonreciprocity.

Conclusions:

• The proposed hybrid temporal-static metasurface platform enables nonreciprocal responses in the NIR.
• This work offers a new pathway for developing tunable optical isolators and other advanced photonic devices.