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(a) Schematic showing laser beam propagation in (i) a stationary medium versus (ii) a moving medium that exhibits a transverse shift of $\Delta y$ Δ y . For simplicity of illustration, we show the laser beams as pulses. (b) The edge of a rotary ruby rod is used to achieve an approximately linear motion in the ${-}y$ − y ( ${+}y$ + y ) direction when the crystal rotates clockwise (counterclockwise). (c) Single frame imaged at the input face of the crystal ( $z = - 2\;{\rm cm} $ z = − 2 c m ) showing o- and e-beams propagated through the 2 cm long ruby crystal. (d) Diagram showing the trajectories of o- and e-beams at different crystal orientations highlighting the change in intensity of each beam at 45 deg intervals. The red “x” shows the center of intensity (COI) position for different crystal orientations highlighting the emergence of a figure-eight-like pattern, while o- and e-beams are shown by green and blue dots, respectively, with varying transparency to signify their relative intensities.
Source publication
Light propagating in a moving medium is subject to light drag. While the light drag effect due to the linear refractive index is often negligibly small, the light drag can be enhanced in materials with a large group index. Here we show that the nonlinear refractive index can also play a crucial role in the propagation of light in moving media and r...
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Objectives
To investigate if the Jenkins Sleep Scale (JSS) demonstrates sex-related differential item functioning (DIF).
Design
Cross-sectional study.
Setting
Survey data from the Finnish Public Sector study (2015–2017).
Participants
77 967 employees in the Finnish public sector, with a mean age of 51.9 (SD 13.1) years and 82% women.
Outcome me...
Citations
... Investigating the relative validity of the sluggish time-dependent absorption theory versus the coherent population oscillation theory will require further experimental investigations. However, this experimental investigation does serve to better understand the nature of the pulse delay and pulse advancement in transition-metal-doped crystals, which is crucial for applications in optical delay lines and optical memories [6,7,24], optical gyroscopes [12,13], and photon drag [25,26]. Similar to many other slow-and fast-light effects, the bandwidth of the observed effect is limited and is given by the inverse of the lifetime of the metastable state. ...
... However, the RSA spectral region is expected to span tens of nanometers [27]. In addition, the strong RSA in ruby allows one to study negative photon drag and other phenomena in a moving nonlinear medium [26,28], as well as to observe the shadow of a laser beam [29]. ...
Reverse saturation of absorption is a relatively rare phenomenon in light–matter interaction, as it requires a few conditions to be fulfilled. We observe that ruby exhibits a very strong reverse saturation of absorption at 473 nm. Furthermore, we measure the group velocity of a modulated laser beam in ruby and observe that the peaks of the pulses appear more than a hundred microseconds earlier than the reference signal. A theoretical model based on coherent population oscillation would suggest a fast-light effect with an extremely large and negative group index of −(1.7 ± 0.1) × 10⁶ in consistency with the observed temporal advancement. We propose that this pulse advancement can also be described by time-dependent absorption of ruby. Our study helps to understand the nature of the fast- and slow-light effects in transition-metal-doped crystals such as ruby and alexandrite with potential applications in optical memories and delay lines.
... This confirms the expectation that the shadow should be the same as size as the object [criterion (iv)] and that it is caused by blocking rather than diverting the illuminating light [criterion (iii)]. Another possible hypothesis for the width discrepancy between measurements and the theoretical model is a self-focusing process as the object laser beam (green) goes through the ruby cube [26]. ...
Light, being massless, casts no shadow; under ordinary circumstances, photons pass right through each other unimpeded. Here, we demonstrate a laser beam acting like an object — the beam casts a shadow upon a surface when the beam is illuminated by another light source. We observe a regular shadow in the sense it can be seen by the naked eye, it follows the contours of the surface it falls on, and it follows the position and shape of the object (the laser beam). Specifically, we use a nonlinear optical process involving four atomic levels of ruby. We are able to control the intensity of a transmitted laser beam by applying another perpendicular laser beam. We experimentally measure the dependence of the contrast of the shadow on the power of the laser beam, finding a maximum of approximately 22%, similar to that of a shadow of a tree on a sunny day. We provide a theoretical model that predicts the contrast of the shadow. This work opens new possibilities for fabrication, imaging, and illumination.
... This is a rotational analogue to the transverse drag of o-and e-beams recently observed by Hogan et al. [60]. While similar in form, (3.9) accounts from inertia and differs from the rigid-body rotation formula (2.3) in that the term in brackets now involves rest-frame indexes (n g ′ and n′), which we have seen in (3.7) are modified by inertia, as opposed to indexes absent motion (n ‾g and n ‾ ) in (2.3). ...
... Specifically, since n g + up ′ n + up ′ − 1 < 0, the (+) ray experiences anomalous drag [62], i.e. is being dragged in the direction opposite to the medium motion. We note that this behaviour, which is here again entirely due to inertia, differs from that in a birefringent glass rod where o-and e-beams are dragged in the same direction [60]. ...
Light dragging phenomena in accelerated media have classically been modelled neglecting the effect of inertia on the dielectric response of the media. Here, we show that the inertial corrections due to a rotating motion can have a profound impact on light-dragging manifestations, leading notably to birefringence in media that are isotropic at rest. By applying these findings to a rotating unmagnetized plasma, we further reveal how inertia plays, in this case, a dominant role, offering unique opportunities to expose these new effects. Inertia is notably demonstrated to be the source of non-zero drag and enhanced polarization drag, pointing to fundamental differences between linear and angular momentum coupling. In taking advantage of the singular properties of plasmas, this work more generally underlines how rest-frame properties are affected by an accelerated motion, and how these modifications can carry over to wave dynamics.
... This is a rotational analog to the transverse drag of o-and e-beams recently observed by Hogan et al. [41]. Also, one recovers immediately from Eq. (2) the drag angle Eq. (1) previously derived for n ′ g =n g and n ′ =n [35], i.e. neglecting rest-frame corrections. ...
... Specifically, since (n ′ g n ′ ) up − < 1, the (−) ray experiences anomalous drag [42], i.e. is being dragged in the direction opposite to the medium motion. Note that this behaviour, which again is here entirely due to inertia, differs from that in a birefringent glass rod where oand e-beams are dragged in the same direction [41]. ...
The signature of light dragging in a rotating unmagnetized plasma is studied analytically. In contrast with previous work which focused exclusively on the drag effects arising from rigid rotation, we examine here the supplemental contribution of inertia to the rest-frame dielectric properties of a rotating medium. We reveal, for
the first time, that these so far neglected contributions actually play a dominant role on light dragging in rotating unmagnetized plasmas. Besides birefringence and enhanced polarization drag, inertia is notably demonstrated to be the cause of a non-zero drag, pointing to fundamental differences between linear and angular momentum coupling. We finally discuss how, thanks to the more favourable scaling elicited here, it may be possible to observe these effects in recently proposed laser driven rotating plasmas, identifying new promising directions for experimental investigations.
... In addition to the linear dispersion, nonlinear corrections to the chromatic dispersion as a function of the wave intensity have been reported for water and acoustic waves [4][5][6]. For optical systems, the photon-atom interactions in general bring the nonlinear dispersion effects [7][8][9][10][11]. With intensity-dependent dispersion only, the supported soliton solutions are formed due to the interplay between the constant coefficient dispersion and the intensity-dependent dispersion, leading to a continuous family of solitary wave solutions [12,13]. ...
A generalized nonlinear Schrödinger equation is studied with the interplay between Kerr nonlinearity and intensity-dependent dispersion. The supported soliton solutions are characterized analytically in different families by the pseudo-potential method, in terms of Maimistov and Cuspon solitons for different ratio between the intensity-dependent dispersion and Kerr nonlinearity. Direct numerical simulations also agree with our analytical formulas. In addition to the well-studied Kerr-type nonlinearity, our results reveal an unexplored scenario with the introduction of the nonlinear corrections to wave dispersion.
Fully describing light propagation in a rotating, anisotropic medium with thermal nonlinearity requires modeling the interplay between nonlinear refraction, birefringence, and the nonlinear group index. Incorporating these factors into a generalized coupled nonlinear Schrödinger equation and fitting them to recent experimental results reveals two key relationships: the photon drag effect can have a nonlinear component that is dependent on the motion of the medium, and the temporal dynamics of the moving birefringent nonlinear medium create distorted figure-eight-like transverse trajectories at the output. The beam trajectory can be accurately modeled with a full understanding of the propagation effects. Efficiently modeling these effects and accurately predicting the beam's output position has implications for optimizing applications in velocimetry and beam steering. Understanding the roles of competitive nonlinearities gives insight into the creation or suppression of nonlinear phenomena like self-action effects.
