Omnidirectional nonreciprocal absorber realized by the magneto-optical hypercrystal

Area of Science:

• Optics and Photonics
• Materials Science
• Metamaterials

Background:

• Photonic bandgap engineering is crucial for controlling light-matter interactions.
• Traditional photonic bandgaps exhibit angular dispersion, limiting wide-angle optical device applications.
• Hypercrystals, incorporating hyperbolic metamaterials (HMMs), offer modified bandgap properties due to anomalous wavevector dispersion.

Purpose of the Study:

• To propose and design nonreciprocal and flexible photonic bandgaps in one-dimensional photonic crystals.
• To utilize magneto-optical HMMs and phase variation competition for novel bandgap control.
• To achieve specific cavity modes for unidirectional light manipulation.

Main Methods:

• Fabrication of one-dimensional photonic crystals with layered magneto-optical HMMs and isotropic dielectric layers.
• Exploiting phase variation competition between HMM and dielectric layers.
• Designing zero-shift and blueshift cavity modes for forward and backward propagation, respectively.

Main Results:

• Demonstrated nonreciprocal and flexible photonic bandgaps.
• Achieved maximum absorption of 0.99 (0.25) for forward (backward) incident light at 367 nm.
• Observed cavity modes with zero-shift (forward) and blueshift (backward) characteristics.

Conclusions:

• The proposed nonreciprocal omnidirectional cavity mode facilitates the design of perfect unidirectional optical absorbers.
• This approach enables wide-angle operation for optical devices.
• Significant applications are identified for all-angle reflectors and filters.