Polarization-Insensitive Transmissive Metasurfaces Using Pancharatnam-Berry and Resonant Phases in Microwave Band.

Most of the existing metasurfaces are effective for the incident wave with the specific circularly polarized (CP) or linearly polarized (LP) state, that is the polarization-sensitive metasurface. This drawback dramatically hinders the practical use of the metasurface. Herein, this paper presents a strategy of polarization-insensitive transmissive microwave metasurfaces to manipulate the incident wave with arbitrary CP and LP states. The metasurface consists of polarization-insensitive unit cells. For the left circularly polarized (LCP) and right circularly polarized (RCP) incident waves, the same abrupt phase covering 0° to 360° can be realized by combining the Pancharatnam-Berry (PB) and resonant phases. As the arbitrary LP wave can decompose into the LCP and RCP waves, metasurfaces consisting of designed unit cells are valid for any polarization states. The polarization-insensitive transmissive microwave metalens and orbital angular momentum multiplexing metasurface working at 23 GHz are devised for verification. Simulation and measurement results verify the availability of the approach. The proposed method is suitable for designing microwave-transmissive metasurfaces capable of polarization insensitivity.

Efficacy and safety of combination of magnesium sulfate, phentolamine and nifedipine in treatment of patients with hypertensive disorder complicating pregnancy.

Efficacy and safety of the combination of magnesium sulfate, phentolamine and nifedipine in the treatment of patients with hypertensive disorder complicating pregnancy (HDCP) and its effect on hemodynamics and urinary protein level were investigated. One hundred and six patients with HDCP diagnosed at the Affiliated Hospital of Beihua University from February 5, 2016 to May 9, 2017 were retrospectively analyzed. Patients were divided into the magnesium sulfate group and the combination group, according to the therapeutic schemes. The efficacy 1 week later was observed. The general clinical data of the patients were recorded, and data were acquired with respect to hemodynamic indexes before and after treatment [changes of S/D ratio of umbilical artery flow, and cardiac index and total peripheral resistance (TPR)], the 24-h urinary protein level, clinical efficacy and safety [adverse drug reactions (ADR) and maternal and neonatal outcomes]. Before treatment, there was no statistically significant difference between the two groups in terms of S/D ratio of umbilical artery flow (P>0.05), while after treatment the S/D ratio was significantly lower than that before treatment in both groups (P<0.05). Before treatment, there was no statistically significant difference between the two groups in terms of cardiac index (P>0.05). TPR after treatment was significantly lower than that before treatment in both groups (P<0.001). Compared with the magnesium sulfate group, patients in the combination group had significantly lower 24-h urinary protein level after treatment (P<0.001), significantly higher total effective rate (P<0.05), significantly lower incidence rate of ADR (P<0.001), and significantly lower incidence rate of adverse maternal and neonatal outcomes (P<0.001). In conclusion, the combination of magnesium sulfate, phentolamine and nifedipine can significantly improve the hemodynamic indexes, the 24-h urinary protein level, the clinical efficacy, ADR and maternal and neonatal outcomes of patients with HDCP, therefore it is worthy of use in the clinic.

Engineering deceleration and acceleration of soliton emitted from Airy pulse with quadratic phase modulation in optical fibers without high-order effects.

Soliton propagation direction can be engineered in optical fibers in the presence of high-order effects (HOEs). It is well known that Raman effects can decelerate the soliton. Here we investigate the manipulation of the deceleration or acceleration of soliton emitted from Airy pulse whose spectrum is imposed an initial quadratic phase modulation (QPM) in optical fibers in the absence of HOEs. We show that, under the action of the anomalous second-order dispersion (SOD) and Kerr nonlinearity, Airy pulse with QPM is able to emit soliton with acceleration or deceleration depending on whether the QPM is negative or positive, and at a rate that is determined by the magnitude of QPM. The reason is that the acceleration behaviors of incident Airy pulse is altered depending on whether SOD and QPM have the same or opposite signs. Our study shows the possibility of controlling and manipulating the soliton propagation and interaction in optical fibers without HOEs, by purposely choosing appropriate QPM parameter of an Airy pulse.

Effect of initial frequency chirp on Airy pulse propagation in an optical fiber.

We study both analytically and numerically the propagation dynamics of an initially chirped Airy pulse in an optical fiber. It is found that the linear propagation of an initially chirped Airy pulse depends considerably on whether the second-order dispersion parameter ß(2) and chirp C have the same or opposite signs. For ß(2)C<0, the chirped Airy pulse first undergoes an initial compression phase, then reaches a breakup area as depending on the values of C, and then experiences a lossy inversion transformation such that it continues to propagate with an opposite acceleration. The chirped Airy pulse is always dispersed during propagation in the case of ß(2)C>0. The impact of truncation coefficient and Kerr nonlinearity on the chirped Airy pulse propagation is also disclosed separately.

Observation of central wavelength dynamics in erbium-doped fiber ring laser.

We report on the observation of central wavelength dynamics in an erbium-doped fiber ring laser by using the nonlinear polarization rotating technique. The evolution of central wavelength with the laser operation state was observed experimentally. Numerical simulations confirmed the experimental observation and further demonstrated that the dynamics of wavelength evolution is due to the combined effects of fiber birefringence, fiber nonlinearity, and cavity filter.