Abstract Under the introduction of any tilted interface in its trajectory, an optical beam experiences polarization‐dependent deflections in the longitudinal and transverse directions with respect to the plane of incidence. The physics of such optical beam shifts are connected to profound universal wave phenomena governed by the fine interference effects of wave packets and have opened up avenues toward metrological applications. Here, the inherent non‐separability of the longitudinal and transverse optical beam shifts is revealed by considering a rather simple case of a partially reflecting Gaussian laser beam from a dielectric interface. This non‐separability appears substantially at some particular regions in the corresponding experimental parameter space. This manifests as a position–position non‐separable state of classical light field. The tunability of the related experimental parameters offers control over the degree of non‐separability. These findings are expected to be a step forward in the exploration of optical beam shifts and a number of analogous universal phenomena. The initial observation also indicates its practical impact on metrology and generation of high‐quality tunable position–position non‐separable states of classical light fields.
Abstract Under the introduction of any tilted interface in its trajectory, an optical beam experiences polarization‐dependent deflections in the longitudinal and transverse directions with respect to the plane of incidence. The physics of such optical beam shifts are connected to profound universal wave phenomena governed by the fine interference effects of wave packets and have opened up avenues toward metrological applications. Here, the inherent non‐separability of the longitudinal and transverse optical beam shifts is revealed by considering a rather simple case of a partially reflecting Gaussian laser beam from a dielectric interface. This non‐separability appears substantially at some particular regions in the corresponding experimental parameter space. This manifests as a position–position non‐separable state of classical light field. The tunability of the related experimental parameters offers control over the degree of non‐separability. These findings are expected to be a step forward in the exploration of optical beam shifts and a number of analogous universal phenomena. The initial observation also indicates its practical impact on metrology and generation of high‐quality tunable position–position non‐separable states of classical light fields.
Under the introduction of any interface in its trajectory, an optical beam experiences polarization-dependent deflections in the longitudinal and transverse directions with respect to the plane of incidence. The physics of such optical beam shifts is connected to profound universal wave phenomena governed by the fine interference effects of wave packets and has opened up avenues towards metrological applications. Here, we reveal the inherent non-separability of the longitudinal and transverse beam shifts by considering a rather simple case of a partially reflecting Gaussian laser beam from a dielectric interface. This non-separability appears substantially in some particular regions in the corresponding parameter space. We further show that such non-separability manifests as a position-position classically entangled state of light. The tunability of the related experimental parameters offers control over the degree of entanglement. Uncovering of the inherent non-separability of the two types of beam shifts is expected to enrich the physical origin of this fundamental effect, impact the understanding of numerous analogous effects, and might find useful applications by exploiting the position-position-polarization classical entanglement in a fundamental Gaussian beam.
As a paraxial wave packet is reflected or refracted from a planar interface separating two material media, it experiences spatial and angular shifts of its center position with respect to predictions of the geometrical ray picture. These in-plane and out-of-plane beam shifts are known as Goos-Hänchen and Imbert-Fedorov shifts, respectively. We discover a universal link between the phase-space nonseparability of an incident wave packet of any degree of spatial coherence and the reflected beam shifts. We unveil coherence Goos-Hänchen and coherence Hall effects, absent in the fully coherent limit. While the former effect can trigger a pronounced enhancement of the spatial Goos-Hänchen shift, the latter enables control of the spatial Imbert-Fedorov shift, from complete cancellation at a certain incidence angle to dramatic enhancement of the shift to giant magnitudes for nearly incoherent incident wave packets. Our results are equally applicable to optical, x-ray, and neutron, as well as matter waves, and they showcase novel phenomena in wave-matter interactions.
Since the establishment of modern optics, the physical nature of light has been debated for centuries, which finally led to the mainstream theory of waveparticle duality. This theory holds that photons intrinsically possess both particle and wave properties, and it is adopted to interpret diverse optical phenomena including rectilinear propagation, polarization, interference and diffraction, forming the fundamental framework of modern quantum optics. Nevertheless, the theory of waveparticle duality contains inherent logical defects. Its essential flaw lies in confusing two completely distinct physical concepts: the intrinsic properties of a substance itself and the morphological features of its motion trajectory. Conventional theories mistake the apparent waveshaped trajectory produced by particle motion for the intrinsic wave property of microparticles, resulting in persistent conceptual ambiguity, missing physical mechanisms and logical inconsistencies within microoptics. This paper constructs an optical underlying model from a purely particle perspective to clarify the real mechanism behind waveparticle phenomena of light. A photon is an indivisible, nonspreading, nontrailing pointlike physical particle with no intrinsic wave property. While propagating, a photon travels along a fixed straightline direction and undergoes inherent transverse oscillation within the plane perpendicular to its propagation direction. At the moment of its generation, a photon uniquely fixes its transverse oscillation angle, amplitude and frequency within the 360degree plane perpendicular to its travelling direction. Once determined, these parameters remain constant throughout propagation without random shifts or arbitrary changes. Superposition of the photon’s longitudinal rectilinear motion and fixedangle transverse oscillation generates a standard sinusoidal trajectory. Consequently, all wavelike features observed in optics are geometric apparent effects originating from particle motion trajectories, rather than material properties intrinsic to photons. Based on this model, this paper reinterprets the core physical mechanism behind doubleslit interference. Contrary to the traditional explanation of photon selfinterference or wavefield superposition, interference fringes arise from microscopic mechanical interactions between transverselyoscillating photons and slit walls when photons pass through the slits. Such interactions regularly deflect photon flight angles. After being deflected and filtered by slits, large numbers of photons form uneven statistical distributions on the receiving plane and produce macroscopically observable lightanddark fringes. This paper also defines the threshold for photonphoton interactions. Ordinaryenergy photons such as visiblelight, infrared and ultraviolet photons do not interact, collide or exchange energy with one another in free space. Only gammaraylevel highenergy photons may collide, undergo energy annihilation, and convert into material particles such as electronpositron pairs. Relying entirely on classical mechanical superposition principles and discarding the contradictory hypothesis of waveparticle duality, the proposed purelyparticle model provides selfconsistent explanations for core classical optical phenomena and achieves analytical revision for the underlying logic of optical waveparticle phenomena.
In conventional optics for light waves, the pioneering work by Goos-Hänchen in 1947 on the lateral shift (or displacement) of a light beam along the surface of a dielectric boundary under the condition of total reflection has stimulated a large number of studies. The key physics behind the Goos-Hänchen shift is the nature of wave interference. From the perspective of wave optics, the incident beam of a finite transverse width can be viewed as composed of plane wave components, each of which has a slightly different transverse wavevector. Each wave component, after the total internal reflection, undergoes a different phase shift, and the superposition of all the reflected wave components gives rise to the lateral shift of the intensity peak in the reflected beam.
In an atom interferometry experiment, the output phase shift depends on the wave vector of photons and the recoil momentum in optical transitions. This Letter puts forward a hypothesis that in light-atom interaction, the atom wave function could provide a transverse confinement to photons and thus could affect the mean recoil momentum. We propose a model to analyze the photon effective wave vector in a monochromatic optical field and calculate the relative shift of |k[over →]_{eff}| to k when an atom with a 3D Gaussian wave function absorbs one photon in a Gaussian beam. This shift could lead to a systematic effect related to the spatial distribution of atoms and the transverse beam profile in high-precision experiments based on atom interferometry.