Hasil untuk "Optics. Light"

J. Wallentin, N. Anttu, Damir Asoli et al.

E. Goulielmakis, M. Schultze, M. Hofstetter et al.

Lihong V. Wang, Hsin-i Wu

K. Bliokh, D. Smirnova, F. Nori

A quantum twist on classical optics Interpreting recent experimental results of light interactions with matter shows that the classical Maxwell theory of light has intrinsic quantum spin Hall effect properties even in free space. Complex effects in condensed-matter systems can often find analogs in cleaner optical systems. Bliokh et al. argue that the optical systems exhibiting such complex phenomena should also be simpler (see the Perspective by Stone). Their theoretical study shows that free-space light has a nonzero topological spin Chern number and thus should have counterpropagating surface modes. Such modes are actually well known and can be described as evanescent modes of Maxwell equations. Science, this issue p. 1448; see also p. 1432 A theoretical study reveals that quantum effects may manifest in classical optical experiments. [Also see Perspective by Stone] Maxwell’s equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are evanescent waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in evanescent waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell’s theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces.

V. Almeida, Qianfan Xu, C. Barrios et al.

P. Tien

R. Loudon, M. Scully

D. Chang, V. Vuletić, M. Lukin

Shaohua Pi, Shaohua Pi, Shaohua Pi et al.

The retina, a crucial component of the human eye for vision, is responsible for converting light signals into neural signals that the brain can interpret. It’s a complex tissue, rich in photoreceptors, and supported by various other cell types, including inner nuclear layer cells, ganglion cells, pigmented epithelial cells, immune cells, and vascular cells. Each of these cells plays a vital role in visual processing and understanding of their function and interactions are essential for assessing vision health and diagnosing diseases. Traditionally, studying the retinal cells has relied heavily on histological techniques, which, despite their utility, offer only static images and require invasive procedures that preclude the observation of dynamic biological processes. In this context, recent advancements of in vivo imaging technologies have marked a significant leap forward. Techniques such as ophthalmoscopy, optical coherence tomography (OCT), adaptive optics (AO), two-photon excitation microscopy (TPM), and light-sheet fluorescence microscopy (LSFM) now enable the direct observation of retinal cells in living organisms. This shift from invasive, static methods to dynamic, non-destructive imaging allows for a more nuanced understanding of retinal cell behavior under physiological conditions. It opens up new avenues for the study of the retina’s complex ecosystem in both health and disease, facilitating early diagnosis of retinal conditions and offering new strategies for treatment. By offering a window into the live retina, in vivo imaging stands as a cornerstone of contemporary ophthalmology, promising to enhance our understanding of eye health and to spur innovations in the diagnosis and treatment of ocular diseases.

Haixia Cui, Wanjiao Li, Qianxi Li et al.

Abstract Real-time dynamic and three-dimensional (3D) X-ray imaging are the most challenging types of X-ray imaging technology, placing more rigorous standards on scintillators. Lead-based (Pb2+) organic-inorganic hybrid halide (OIHH) scintillators with high X-ray absorption coefficients have been demonstrated to exhibit excellent scintillation performance. However, their toxicity and instability hindered further development, and it is necessary to explore novel low-toxic metal-based OIHHs possessing excellent scintillation performance. Antimony-based (Sb3+) OIHHs are not only environmentally friendly, but also show good stability compared to Pb2+-based OIHHs, which make them promising candidates as excellent scintillators. Currently, the understanding of Sb3+-based OIHH scintillators for X-ray detection and imaging is still in infancy and requires further exploration. Herein, we designed two Sb3+-based OIHH crystals of (BPP)2SbCl5 (CP1) and (BPP)2SbCl5 0.5 H2O (CP2), which have very similar crystal structures except the introduction of water molecules in CP2. Experimental and theoretical results reveal that CP2 has larger lattice distortion and smaller freedom of motion, which can promote the self-trapped excitons emissions. A flexible scintillator screen based on CP2 crystals was prepared and applied for real-time dynamic and 3D X-ray imaging, which is the first time for Sb3+-based OIHH scintillators and significantly broadens the potential of Sb3+-based OIHH scintillators.

Hengzhou Liu, Anthony Fiorito, D. Ryan Sheffield et al.

An apparatus that records the optical spectrum of emissive materials as a function of the polar coordinate angles is reported. The ability for the device to characterize the directive gain of a light source over the optical spectrum is demonstrated. The angular emission profile of an electrically driven LED with a hemispherical diffuser cap was measured. In addition, the device was used to characterize optically pumped materials exhibiting both fluorescence and amplified spontaneous emission (ASE), demonstrating its versatility for diverse emissive systems.

Munazza Zulfiqar Ali

The hyperbolic metamaterial shows anisotropic epsilon near zero (ENZ) behaviour in different frequency ranges. Here two different periodic structures of hyperbolic metamaterial are investigated theoretically. Periodicity of the structure gives rise to transmission gaps at different frequency ranges around such a behaviour. The characteristics of these gaps are elaborated by transmission plots and their dependence on different parameters of the structure is studied. The intriguing properties of ENZ behaviour combined with transmission gaps in periodic arrangements give rise to interesting phenomena and can be focus of further explorations.

Wenhui Hao, Zhihui Yang, Mingwei Mao et al.

Spatiotemporally mode-locked (STML) fiber lasers have been a remarkable platform for exploring multidimensional nonlinear optical dynamics and developing novel photonic devices. However, realizing high-selective transverse-mode control of STML fiber lasers is still very challenging. Here, we report transverse-mode selective operation of a 1-μm STML fiber laser by using a self-designed mode-coupling (MC) device, effectively tuning the mode-locked fiber laser across different transverse-mode states, lower-order modes, moderate-order modes and higher-order modes. In each mode state, various pulsing states including single pulse, pulse group, and multi-pulses are also achieved, with individual pulse duration tunable from 560 ps to 335 ps. What's more, STML pulses with high pulse energy of 531 nJ are realized by using large-mode-area gain fiber and highly chirping the laser pulse. Spectral width of the STML fiber laser is as narrow as 140 pm.

Qi Liu, Yu Tian, Zhaohua Tian et al.

Abstract For the requirement of quantum photonic integration in on-chip quantum information, we propose a scheme to realize quantum controlled-Z (CZ) gates through single gradient metasurface. Using its parallel beam-splitting feature, i.e., a series of connected beamsplitters with the same splitting ratio, one metasurface can support a polarization encoding CZ gate or path encoding CZ gate, several independent CZ gates, and cascade CZ gates. Taking advantage that the path of output state is locked by the polarization of input state, path encoding CZ gates can efficiently filter out bit-flip errors coming from beam-splitting processes. These CZ gates also have the potential to detect quantum errors and generate high-dimensional entanglement through multi-degree-of-freedom correlation on metasurfaces. By integrating quantum CZ gates into a single metasurface, our results open an avenue for high-density and multifunctional integration of quantum devices.

Christopher Perrella, Kishan Dholakia

Abstract An original form of photonic force microscope has been developed. Operating with a trapped lanthanide-doped crystal of nanometric dimensions, a minimum detected force of the order of 110 aN and a force sensitivity down to 1.8 fN/ $$\sqrt{{\rm{Hz}}}$$ Hz have been realised. This opens up new prospects for force sensing in the physical sciences.

Yuri Aleksandrovich Konstantinov, Artem Timofeevich Turov, Konstantin Pavlovich Latkin et al.

This work is devoted to the scientific and technical aspects of individual stages of active optical fibers preforms’ optical-geometric parameters metrological control. The concept of a system presented makes it possible to carry out a study of a rare earth element distribution in the preform of an active optical fiber and to monitor geometric parameters, and also to study the evolution of the refractive index profile along the length of the sample at a qualitative level. As far as it is known, it is the first description of the preform optical, geometric, and luminescent properties measurement within a single automated laboratory bench. Also, the novelty of the approach lies in the fact that the study of the refractive index profile variation along the length of the preform is, for the first time, conducted using the “dry” method, that is, without immersing the sample in synthetic oil, which makes the process less labor-intensive and safer.

Jun Li, Ruixu Yao

This work utilizes the CEEMDAN algorithm to analyze the interference of Rayleigh back-scattering signals in standard communication optical fibers. The technology has several advantages, such as anti-electromagnetic interference, improved electrical insulation, corrosion resistance, higher sensitivity, and the capability for long-distance monitoring. In this study, in-situ monitoring data from a 53.2 km natural gas pipeline in a terrain area in Southwest China were analyzed. The results demonstrate that, using the CEEMDAN algorithm for a blind test conducted over fourteen days, a 100% recognition accuracy for mechanical tamping and a Nuisance Alarm Rate (NAR) of less than 1% were achieved.

E. Shahmoon, D. Wild, M. Lukin et al.

We consider light scattering off a two-dimensional (2D) dipolar array and show how it can be tailored by properly choosing the lattice constant of the order of the incident wavelength. In particular, we demonstrate that such arrays can operate as a nearly perfect mirror for a wide range of incident angles and frequencies, and shape the emission pattern from an individual quantum emitter into a well-defined, collimated beam. These results can be understood in terms of the cooperative resonances of the surface modes supported by the 2D array. Experimental realizations are discussed, using ultracold arrays of trapped atoms and excitons in 2D semiconductor materials, as well as potential applications ranging from atomically thin metasurfaces to single photon nonlinear optics and nanomechanics.

P. Lodahl, S. Mahmoodian, S. Stobbe et al.

Advanced photonic nanostructures are currently revolutionizing the optics and photonics that underpin applications ranging from light technology to quantum-information processing. The strong light confinement in these structures can lock the local polarization of the light to its propagation direction, leading to propagation-direction-dependent emission, scattering and absorption of photons by quantum emitters. The possibility of such a propagation-direction-dependent, or chiral, light–matter interaction is not accounted for in standard quantum optics and its recent discovery brought about the research field of chiral quantum optics. The latter offers fundamentally new functionalities and applications: it enables the assembly of non-reciprocal single-photon devices that can be operated in a quantum superposition of two or more of their operational states and the realization of deterministic spin–photon interfaces. Moreover, engineered directional photonic reservoirs could lead to the development of complex quantum networks that, for example, could simulate novel classes of quantum many-body systems.

Yudai Matsumura, Yu Tokizane, Eiji Hase et al.

THz waves are promising wireless carriers for next-generation wireless communications, where a seamless connection from wireless to optical communication is required. In this study, we demonstrate carrier conversion from THz waves to dual-wavelength NIR light injection-locking to an optical frequency comb using asynchronous nonpolarimetric electro-optic downconversion with an electro-optic polymer modulator. THz wave in the W band was obtained as a stable photonic RF beat signal of 1 GHz with a signal-to-noise ratio of 25 dB via the proposed THz-to-NIR carrier conversion. In addition, the results imply the potential of the photonic detection of THz waves for wireless-to-optical seamless communication.