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Additional Nonreciprocity Effects in the Magneto-Optics of Asymmetric Layer Structures
摘要： It has been shown that space–time inversion symmetry breaking at the normal incidence of a quasiplane wave on an asymmetric multilayer structure in the Voigt geometry can result in the formation of the angular Goos–H?nchen effect at reflection and transmission, as well as the spatial Goos–H?nchen effect at transmission. The effects are characterized by nonreciprocity not only with respect to the inversion of direction of static magnetic field but also with respect to the permutation of nongyrotropic layers surrounding a gyrotropic layer.
关键词： asymmetric layer structures,nonreciprocity,Voigt geometry,magneto-optics,Goos–H?nchen effect
更新于2025-09-23 15:22:29
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Nonreciprocity and zero reflection in nonlinear cavities with tailored loss
摘要： We demonstrate how to tailor the losses of nonlinear cavities in order to suppress their re?ection and enhance their nonreciprocal transmission. We derive analytical expressions predicting the existence of zero-re?ection channels in single and coupled nonlinear cavities, depending on the driving frequency and loss rates. While suppressing the re?ection from a single cavity imposes a stringent condition on the input-output leakage rates, we demonstrate that this condition can be signi?cantly relaxed in systems of coupled cavities. In particular, zero-re?ection and nonreciprocity can be achieved across a range of driving frequencies in coupled cavities by tuning the output leakage rate alone. Numerical calculations based on the driven-dissipative Gross-Pitaevskii equation, usually employed to describe microcavity polaritons, reveal the spatial phenomenology associated with zero-re?ection states and provide design guidelines for the construction of nonlinear optical isolators.
关键词： optical isolators,nonreciprocity,nonlinear cavities,tailored loss,zero re?ection
更新于2025-09-19 17:15:36
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Broadband Nonreciprocity Enabled by Strong Coupling of Magnons and Microwave Photons
摘要： Nonreciprocity of signal transmission enhances the capacity of communication channels and protects the transmission quality against possible signal instabilities, thus becoming an important component for ensuring coherent information processing. However, nonreciprocal transmission requires breaking time-reversal symmetry (TRS), which poses challenges of both practical and fundamental character that hinder progress. Here we report an alternative scheme for achieving broadband nonreciprocity using a specially engineered hybrid microwave cavity. The TRS breaking is realized via strong coherent coupling between a selected chiral mode in the microwave cavity and a single collective spin excitation (magnon) in a ferromagnetic yttrium iron garnet sphere. The nonreciprocity in transmission is observed to span nearly a 0.5-GHz frequency band, which outperforms by two orders of magnitude the previously achieved bandwidths. Our findings suggest a promising direction for robust coherent information processing in a broad range of systems in both the classical and the quantum regime.
关键词： Broadband nonreciprocity,Time-reversal symmetry breaking,Microwave cavity,Magnon-photon coupling,Nonreciprocity
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Nonmagnetic Linear Optical Nonreciprocity in Acoustically Driven Resonant Waveguide Gratings
摘要： Nonmagnetic nonreciprocal linear optical response is predicted for acoustically driven resonant waveguide gratings. In a narrow spectral range around the resonance the structure can be completely transparent for a light wave propagating in one direction and highly reflective in the opposite direction. As resonances are revealed in the zeroth diffraction order, the frequency of the transmitted/reflected waves is the same as the frequency of the incident wave, while resonantly enhanced guided mode field oscillates at the frequency shifted up or down due to acousto-optic coupling mediated by a traveling sound wave.
关键词： resonant waveguide gratings,acousto-optics,nonmagnetic optical nonreciprocity
更新于2025-09-19 17:13:59
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Nonreciprocal propagation in optical fibers
摘要： Nonreciprocal propagation in optical fibers presents practical interest. The present work treats the problem of nonreciprocal propagation in nonabsorbing cylindrically layered structures at axial magnetization characterized by magnetooptic electrical permittivity, ?ε, and magnetic permeability, ?μ, tensors, using transverse circularly polarized representation. The solutions to the vector Helmholtz equation are expressed analytically as functions of circular cylindrical coordinates (cid:37), ?, and z. The results are applied to a magnetooptic circular cylindrical waveguide and illustrated on fiber waveguides with an yttrium iron garnet (YIG) core and a cladding formed by gallium substituted yttrium iron garnet (GaYIG) at the optical communication wavelength of 1.55 μm. The propagation distance in the waveguide for a π/4 azimuth rotation of a transverse linearly polarized incident wave on the waveguide axis required in isolators is about 100 μm.
关键词： magneto-optical effect,Faraday effect,isolator,nonreciprocity
更新于2025-09-12 10:27:22
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Nonreciprocity in a strongly coupled three-mode optomechanical circulatory system
摘要： In this work, we propose a scheme in three-mode optical systems to simulate a strongly coupled optomechanical system. The nonreciprocity observed in such a three-mode optomechanical circulatory system (OMCS) is explored. To be speci?c, we ?rst derive a quantum Langevin equation (QLE) for the strongly coupled OMCS by suitably choosing the laser ?eld, then we give a condition for the frequency of the laser and the mechanical decay rate, beyond which the optomechanical system has a unidirectional transmission regardless of how strong the optomechanical coupling is. The optomechanically induced transparency is also studied. The present results can be extended to a more general two-dimensional optomechanical system and a planar quantum network, and the prediction is possible to be observed in an optomechanical crystal or integrated quantum superconducting circuit. This scheme paves a way for the construction of various quantum devices that are necessary for quantum information processing.
关键词： Nonreciprocity,quantum Langevin equation,optomechanically induced transparency,quantum information processing,optomechanical circulatory system
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - All-Optical Switching in Microresonators using the Kerr Nonreciprocity
摘要： Photonic circuits are spreading as a viable alternative to conventional electronic circuits. Electro-optic modulators (EOMs) are currently used as switches in telecommunications thanks to their simplicity and speed, however they are driven electrically. Several approaches have been demonstrated to realise all-optical switches such as ring lasers in which the lasing direction is controlled by an input seed, however these devices still require additional electrical or optical pumping. An alternative approach is to exploit the change in resonant frequency of nonlinear resonators with the input power. This has been successfully demonstrated in semiconductor resonators, where the nonlinearity is provided by the carrier generation from two-photon absorption, and in dielectric resonators governed by the Kerr effect. However, this approach needs the input to be in a narrow range of power and detuning from the cavity resonance and is adversely affected by the cavity’s thermal drift due to the high circulating powers. We demonstrate a device that works in a different regime of the Kerr effect. In our case the bistability arises from the twofold contribution of the cross-phase modulation with respect to the self-phase modulation to the refractive index change, Δni ∝ n2(Ii + 2 I j), where i, j are the two possible directions [1,2]. As a consequence, above a threshold power, Pth, light of a given frequency can circulate in just one direction inside the resonator and the switching between the two corresponding states exhibits hysteresis. This regime can be accessed in a much broader range of input powers, from Pth to ～ 5Pth, and the frequency of the laser can drift by up to about 10 GHz thanks to thermal locking [3].
关键词： Kerr nonreciprocity,microresonators,photonic circuits,all-optical switching
更新于2025-09-12 10:27:22
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Realization of Nonlinear Optical Nonreciprocity on a Few-Photon Level Based on Atoms Strongly Coupled to an Asymmetric Cavity
摘要： Optical nonreciprocity is important in photonic information processing to route the optical signal or prevent the reverse flow of noise. By adopting the strong nonlinearity associated with a few atoms in a strongly coupled cavity QED system and an asymmetric cavity configuration, we experimentally demonstrate the nonreciprocal transmission between two counterpropagating light fields with extremely low power. The transmission of 18% is achieved for the forward light field, and the maximum blocking ratio for the reverse light is 30 dB. Though the transmission of the forward light can be maximized by optimizing the impedance matching of the cavity, it is ultimately limited by the inherent loss of the scheme. This nonreciprocity can even occur on a few-photon level due to the high optical nonlinearity of the system. The working power can be flexibly tuned by changing the effective number of atoms strongly coupled to the cavity. The idea and result can be applied to optical chips as optical diodes by using fiber-based cavity QED systems. Our work opens up new perspectives for realizing optical nonreciprocity on a few-photon level based on the nonlinearities of atoms strongly coupled to an optical cavity.
关键词： optical nonreciprocity,few-photon level,asymmetric cavity,nonlinear optics,cavity QED
更新于2025-09-11 14:15:04
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Giant tunable nonreciprocity of light in Weyl semimetals
摘要： The propagation of light in Weyl semimetal films is analyzed. The magnetic family of these materials is known by anomalous Hall effect, which, being enhanced by the large Berry curvature, allows one to create strong gyrotropic and nonreciprocity effects without external magnetic field. The existence of nonreciprocal waveguide electromagnetic modes in ferromagnetic Weyl semimetal films in the Voigt configuration is predicted. Thanks to the strong dielectric response caused by the gapless Weyl spectrum and the large Berry curvature, ferromagnetic Weyl semimetals combine the best waveguide properties of magnetic dielectrics or semiconductors with strong anomalous Hall effect in ferromagnets. The magnitude of the nonreciprocity depends both on the internal Weyl semimetal properties, the separation of Weyl nodes, and the external factor, the optical contrast between the media surrounding the film. By tuning the Fermi level in Weyl semimetals, one can vary the operation frequencies of the waveguide modes in THz and mid-IR ranges. Our findings pave the way to the design of compact, tunable, and effective nonreciprocal optical elements.
关键词： Weyl semimetals,optical elements,anomalous Hall effect,nonreciprocity,waveguide modes
更新于2025-09-11 14:15:04