Lopsided optical diffraction in a loop electromagnetically induced grating

We propose a theoretical scheme in a cold rubidium-87 (87Rb) atomic ensemble with a non-Hermitian optical structure, in which a lopsided optical diffraction grating can be realized just with the combination of single spatially periodic modulation and loop-phase. Parity-time (PT) symmetric and parity-time antisymmetric (APT) modulation can be switched by adjusting different relative phases of the applied beams. Both PT symmetry and PT antisymmetry in our system are robust to the amplitudes of coupling fields, which allows optical response to be modulated precisely without symmetry breaking. Our scheme shows some nontrivial optical properties, such as lopsided diffraction, single-order diffraction, asymmetric Dammam-like diffraction, etc. Our work will benefit the development of versatile non-Hermitian/asymmetric optical devices.

Automated summary

We propose a theoretical scheme in a cold rubidium-87 (87Rb) atomic ensemble that achieves a lopsided optical diffraction grating through a non-Hermitian optical structure with single spatially periodic modulation and loop-phase. The modulation between parity-time (PT) symmetric and parity-time antisymmetric (APT) can be controlled by adjusting relative phases of the applied beams. Our scheme demonstrates robust PT symmetry and PT antisymmetry, enabling precise modulation of optical response without symmetry breaking. The nontrivial optical properties exhibited in our system include lopsided diffraction, single-order diffraction, asymmetric Dammam-like diffraction, etc. Our work contributes to the development of versatile non-Hermitian/asymmetric optical devices.