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Unidirectional amplified reflections based on four-wave mixing and spontaneously generated coherence

Yue Geng, Peng Chen, Xinfu Zheng +4 more

Physics Letters AJan 13, 20253 citations

Unidirectional reflection amplification without inversion

Yiting Zheng, Chen Peng, Guanrong Li +6 more

Physical Review AMar 2, 20260 citations

Spatial susceptibility modulation and controlled unidirectional reflection amplification via four-wave mixing

Yue Geng, Xiaoshan Pei, Guanrong Li +4 more

Control of unidirectional light propagation is of paramount importantance to optical signal processing and optical communication. Especially, the amplified optical signal can isolate noise well that may provide more applications. In this work, we propose a dynamically modulated regime to realize unidirectional reflection amplification in a short and dense uniform atomic medium, and all atoms are driven into four-level double-Λ type by two coupling fields with linearly varied intensities along x direction and two weak probe fields. Based on four-wave mixing resonance and the broken spatial symmetry, the complete nonreciprocal reflection (unidirectional reflection) can be amplified with reflectivity more than 2.0, even to 6.0. In addition, the width, height, and position of the unidirectional reflection bands can be tunable. Thus, our regime is feasible and may inspire further applications in all-optical networks that require controllable unidirectional light amplification.Control of unidirectional light propagation is of paramount importantance to optical signal processing and optical communication. Especially, the amplified optical signal can isolate noise well that may provide more applications. In this work, we propose a dynamically modulated regime to realize unidirectional reflection amplification in a short and dense uniform atomic medium, and all atoms are driven into four-level double-Λ type by two coupling fields with linearly varied intensities along x direction and two weak probe fields. Based on four-wave mixing resonance and the broken spatial symmetry, the complete nonreciprocal reflection (unidirectional reflection) can be amplified with reflectivity more than 2.0, even to 6.0. In addition, the width, height, and position of the unidirectional reflection bands can be tunable. Thus, our regime is feasible and may inspire further applications in all-optical networks that require controllable unidirectional light amplification.

Optics ExpressOct 20, 202312 citations

Degenerate four-wave mixing with the use of incoherent light

Takayoshi Kobayashi, Kazuhiko Misawa, Toshiaki Hattori

laseJan 1, 19890 citations

Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing

Xiao Liu, M. Artoni, Giuseppe Carlo La Rocca +1 more

We propose a scheme for realizing nonreciprocal optical scattering with non-Hermitian four-wave mixing (FWM) in a double-Λ system of cold atoms driven by coupling and dressing phase-mismatched standing-wave (SW) fields. Four scattering channels—direct transmission, cross transmission, direct reflection, and cross reflection—can be established for a probe and a signal field, some of which are nonreciprocal due to non-Hermitian spatial modulations when the two SW driving fields exhibit a π/4 phase shift. We find in particular that it is viable to attain single-color unidirectional transport, dual-color unidirectional transport, and single-color directional blockade with respect to a probe and a signal field incident upon this atomic sample from the same side, due to perfect destructive interference between direct and cross scattering channels. This work provides a new paradigm for studying non-Hermitian nonlinear optics and offers a theoretical foundation for designing all-optical atomic devices based on multi-channel nonreciprocal scattering.We propose a scheme for realizing nonreciprocal optical scattering with non-Hermitian four-wave mixing (FWM) in a double-Λ system of cold atoms driven by coupling and dressing phase-mismatched standing-wave (SW) fields. Four scattering channels—direct transmission, cross transmission, direct reflection, and cross reflection—can be established for a probe and a signal field, some of which are nonreciprocal due to non-Hermitian spatial modulations when the two SW driving fields exhibit a π/4 phase shift. We find in particular that it is viable to attain single-color unidirectional transport, dual-color unidirectional transport, and single-color directional blockade with respect to a probe and a signal field incident upon this atomic sample from the same side, due to perfect destructive interference between direct and cross scattering channels. This work provides a new paradigm for studying non-Hermitian nonlinear optics and offers a theoretical foundation for designing all-optical atomic devices based on multi-channel nonreciprocal scattering.

PhotonicsMay 21, 20252 citations

Observation of amplified reflection through degenerate four-wave mixing at CO_2 laser wavelengths in germanium

David E. Watkins, C. R. Phipps, Stewart J. Thomas

We report the first known observation of amplified reflection through degenerate four-wave mixing at 10.6 microm. Reflectivities of over 100% are reported in both n-type and p-type germanium at pump intensities of about 100 MW/cm(2). The maximum reflectivity reported is 800% in p-type Ge.

Optics LettersFeb 1, 198131 citations

Unidirectional Amplified Reflections Based on Four-Wave Mixing and Spontaneouslygenerated Coherence

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