Broadband and weak-dispersion nonlinear response enhancement in the epsilon-near-zero region of a nano-stepped metasurface.

Optical media with dispersion-free large nonlinearity are highly desired for a broad range of applications, such as spectroscopy, all-optical data processing, and quantum information. Here, we report that a metasurface composed of an indium-tin-oxide nano-step array can exhibit weak-dispersion and enhanced optical nonlinearity theoretically in the region of the spectrum where the real part of its effective permittivity is close to zero. Such nonlinear features are attributed to the offset of the structural dispersion and material dispersion of the metasurface in its epsilon-near-zero region. The nonlinear refractive index of our metasurface remains at around n2 = 1.5 × 10-2 cm2 GW-1 in a wide wavelength range from 1300 to 1510 nm, and the nonlinear absorption coefficient is greater than 1 × 105 cm GW-1 in the range from 1280 to 1780 nm in simulation. Our results open a novel approach to applications of nonlinear photonic devices requiring high integration density and stable performance.

Boosting optical nonlinearity in epsilon-near-zero trilayer coatings.

Materials with large optical nonlinearity are highly desired for various applications such as all-optical signal processing and storage. Recently, indium tin oxide (ITO) has been found to possess strong optical nonlinearity in the spectral region where its permittivity vanishes. Here, we demonstrate that ITO/Ag/ITO trilayer coatings, deposited by magnetron sputtering with high-temperature heat treatment, can significantly enhance the nonlinear response in their effective epsilon-near-zero (ENZ) regions. The obtained results show that the carrier concentrations of our trilayer samples can reach 7.25 × 1021 cm-3, and the ENZ region can shift to the spectrum close to the visible range. In the ENZ spectral region, the ITO/Ag/ITO samples exhibit enhanced nonlinear refractive indices as large as 2.397 × 10-15 m2 W-1, over 27 times larger than that of an individual ITO layer. Such a nonlinear optical response is well described using a two-temperature model. Our findings provide a new paradigm for developing nonlinear optical devices for applications requiring low power.

Work-Family Conflict, Emotional Responses, Workplace Deviance, and Well-Being among Construction Professionals: A Sequential Mediation Model.

Given the dynamic, complex, and highly demanding project environment, construction professionals are particularly likely to experience a high level of work-family conflict. Taking an emotional resource perspective and on the basis of affective events theory, this study tested negative affect and emotional exhaustion as sequential mediators between two directions of work-family conflict and workplace well-being or deviance behavior. The theoretical model was examined using data collected at two time points from 143 construction professionals through regression analysis and bootstrapping. The results indicate that work-family conflict was positively related to deviant behavior and negatively related to workplace well-being. The findings demonstrate that the mediation effects of emotional exhaustion between work-family conflict and workplace well-being or deviant behavior were significant and that the sequential mediating effects of negative affect and emotional exhaustion in the relationship between work-family conflict and workplace well-being or deviant behavior were significant. Moreover, different impacts of work interference with family and family interference with work on job-related attitudes and behavior were observed. These findings highlight the importance of emotional experience to understand the negative impact of work-family conflict in the temporary project context.

Cell transmission model of dynamic assignment for urban rail transit networks.

For urban rail transit network, the space-time flow distribution can play an important role in evaluating and optimizing the space-time resource allocation. For obtaining the space-time flow distribution without the restriction of schedules, a dynamic assignment problem is proposed based on the concept of continuous transmission. To solve the dynamic assignment problem, the cell transmission model is built for urban rail transit networks. The priority principle, queuing process, capacity constraints and congestion effects are considered in the cell transmission mechanism. Then an efficient method is designed to solve the shortest path for an urban rail network, which decreases the computing cost for solving the cell transmission model. The instantaneous dynamic user optimal state can be reached with the method of successive average. Many evaluation indexes of passenger flow can be generated, to provide effective support for the optimization of train schedules and the capacity evaluation for urban rail transit network. Finally, the model and its potential application are demonstrated via two numerical experiments using a small-scale network and the Beijing Metro network.