Search

The electro-optic effect of periodically poled optical superlattice LiNbO[sub 3] (PPLN) was studied. Because of the periodic electro-optic (EO) coefficient, the reciprocal vector of the periodic structure can be used to compensate for the phase mismatch between the ordinary and extraordinary waves, which is similar to the nonlinear optical frequency conversion process. If the quasi-phase-matching condition is satisfied, polarization of a light propagated in PPLN can rotate linearly with the applied electric field, which shows that PPLN may be used as a precise spectral filter or an EO switch. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

An acoustic superlattice LiNbO[sub 3] crystal with periodic ferroelectric domain structure was fabricated by introducing a periodic electric current through the solid-liquid interface during the crystal growing process. The domain morphology of an as-grown crystal was observed with a scanning electron microscope, and was found to be of good periodicity. A light diffraction experiment indicated that there was a periodic fluctuation of the dielectric constant along the crystal's growing direction. Using the "crossed field" scheme, a 340 MHz ultrasonic was excited in the crystal, which means that the acoustic superlattice is suitable for constructing high-frequency bulk-wave acoustic devices. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The compact storage system is a new storage technology in the field of intelligent logistics technology, and its most typical feature is that it can realize multi-depth storage of unit loads. In this paper, the path optimization problem of the co-existence of both single command (SC) and dual command (DC) operations of the stacker in the dual-port layout is studied, and the mathematical model of the problem is established with the shortest travel time of the stacker as the objective. A genetic algorithm (GA)-beam search (BS) hybrid optimization algorithm is designed to solve the model, and the optimal individual obtained by the GA is used as the initial path choice of the BS to avoid local optimum. The effectiveness of the model and algorithm is verified by numerical simulation, and the results show that the operation path optimization model of the stacker and the designed solution method can better adapt to the I/O tasks scheduling requirements in the compact three-dimensional warehouse with dual-port layout, get a more reasonable stacker scheduling scheme, and improve the storage efficiency.

Chirality and hierarchy are two representative features of complex configurations inspiring exotic functions. Chiral additives are adopted to break the mirror symmetry of molecular orientation inside smectic layers, and overcome the restriction on in-layer helical arrangement by virtue of the surface electroclinic effect. The chirality strength of liquid crystals is regulated via the photo-isomerization of chiral molecular switch, the doping concentration control, and the mixing of different chiral additives. The dynamic evolution of chiral smectic superstructures leads to the reversible rotation of oily streaks (OSs), and even structural transformation between OSs and focal conic domains is demonstrated. This releases new freedom of chiral hierarchical configurations and may inspire fantastic applications in active optics, sensing, and micro-manufacturing. [ABSTRACT FROM AUTHOR]

The article presents a research report on programmable self-propelling actuators enabled by a dynamic helical medium. Topics include programmable self-propelling actuators are realized via a specific molecular assembly within a photo responsive cholesteric medium; and understanding of the rotation-translation conversion performed in an exquisitely self-organized system and may inspire future designs for functional materials and intelligent robotics.

Activation of Notch signaling pathway in cancer stem cells plays a crucial role in the regulation of self--renewal and maintenance of side population cells. In the present study, we have identified cancer stem like 2.7% side population cells from nasopharyngeal carcinoma samples whose prevalence was significantly reduced to 0.3% upon verapamil treatment. The protein level of Notch1 and Hes-1 are highly up-regulated in fluorescence-activated cell sorting purified side population cells and thus leads to the elevated expression of stem cell surface proteins (Oct-4, Sox2 and Nanog), which are essential for side population cells self-renewal. In addition, these nasopharyngeal carcinoma side population cells are CD133 and CD44 positive and they possess enhanced cell proliferation rate, highly tumorgenic and invasive. Our findings suggest that Notch1 signaling is a potential target of novel anticancer drugs, which could efficiently target and eradicate the cancer stem cells. [ABSTRACT FROM AUTHOR]

Entanglement distribution has been accomplished using a flying drone, and this mobile platform can be generalized for multiple mobile nodes with optical relay among them. Here we develop the first optical relay to reshape the wave front of photons for their low diffraction loss in free-space transmission. Using two drones, where one distributes the entangled photons and the other serves as relay node, we achieve entanglement distribution with Clauser-Horne-Shimony-Holt S parameter of 2.59±0.11 at 1 km distance. Key components for entangled source, tracking, and relay are developed with high performance and are lightweight, constructing a scalable airborne system for multinode connectio and toward mobile quantum networks. [ABSTRACT FROM AUTHOR]

Weak-value amplification (WVA) is a metrological protocol that amplifies ultrasmall physical effects. However, the amplified outcomes necessarily occur with highly suppressed probabilities, leading to the extensive debate on whether the overall measurement precision is improved in comparison to that of conventional measurement (CM). Here, we experimentally demonstrate the unambiguous advantages of WVA that overcome practical limitations including noise and saturation of photodetection and maintain a shot-noise-scaling precision for a large range of input light intensity well beyond the dynamic range of the photodetector. The precision achieved by WVA is 6 times higher than that of CM in our setup. Our results clear the way for the widespread use of WVA in applications involving the measurement of small signals including precision metrology and commercial sensors. [ABSTRACT FROM AUTHOR]

Vector vortex beams simultaneously carrying spin and orbital angular momentum of light promise additional degrees of freedom for modern optics and emerging resources for both classical and quantum information technologies. The inherently infinite dimensions can be exploited to enhance data capacity for sustaining the unprecedented growth in big data and internet traffic and can be encoded to build quantum computing machines in high-dimensional Hilbert space. So far, much progress has been made in the emission of vector vortex beams from a chip surface into free space; however, the generation of vector vortex beams inside a photonic chip has not been realized yet. Here, we demonstrate the first vector vortex beam emitter embedded in a photonic chip by using femtosecond laser direct writing. We achieve a conversion of vector vortex beams with an efficiency up to 30% and scalar vortex beams with an efficiency up to 74% from Gaussian beams. We also present an expanded coupled-mode model for understanding the mode conversion and the influence of the imperfection in fabrication. The fashion of embedded generation makes vector vortex beams directly ready for further transmission, manipulation, and emission without any additional interconnection. Together with the ability to be integrated as an array, our results may enable vector vortex beams to become accessible inside a photonic chip for high-capacity communication and high-dimensional quantum information processing. [ABSTRACT FROM AUTHOR]