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Nonreciprocal devices such as isolators are well-known in light wave communication systems. The integrated optical isolator is presented where the magnetic field modes propagate perpendicular to the in-plane magnetization of a planar magnetooptical waveguide. The cladding and film of optical isolator are made of magnetic materials with magnetization adjusted to be parallel to their plan. The substrate is filled with new artificial metamaterials (MTMs). The dispersion equation of the transverse magnetic (TM) fields is derived. The difference Δβ between the phase constant for forward and backward propagation is calculated numerically for different values of MTMs permittivity (ε_s) and permeability (μ_s). Results show that the cutoff thickness is different for forward and backward propagation and varies with the MTMs parameters. The cutoff thickness of the isolator is selected such that the coupling coefficients of the isolator with optical fiber are obviously different for forward and backward propagation.

An acoustic black hole (ABH) resonator is regarded as an efficient approach for controlling vibration caused by flexural wave energy. In this paper, the beam models with periodic ABH beam resonators are designed. Both the vibration absorption and isolation performances are investigated. Theoretical models based on the Transfer Matrix Method are presented to evaluate the reflection coefficient, which is validated both by the semi-analytic method combined with the Finite Element Method (FEM) and the Impedance Matrix Method. Meanwhile, FEM models of periodic ABH beam resonators acting as the beam terminator and isolator are established and analyzed. The results show that the periodic ABH beam resonators are of a better vibration reduction performance in lower frequency and have wider bandgaps for lower reflection coefficient and higher transmission loss than the single wedge. Moreover, with the increasing number of periods, the advantages of the periodic ABH beam resonators in reducing vibration become more obvious. Through the complex plane and dynamic analyses, it shows that multimode coupling and meta-damping effect lead to superior performance since the enriched modal content is introduced by the periodic ABH beam structure. This effect is also verified by the experimental result. Besides, the study also reveals the paradoxical relationship between vibration absorption and isolation performances. Additionally, parametric studies are conducted to disclose the effects of structural parameters. Based on the analyses, two approaches are proposed to enhance the vibration reduction performances, including the composite beam resonators and compound beam resonators. This paper illustrates a promising vision for applying the periodic ABH beam resonators to various vibration control fields.

Multiferroic materials and devices have attracted intensified recent interests due to the demonstrated strong magnetoelectric (ME) coupling in new multiferroic materials and devices with unique functionalities and superior performance characteristics. Strong ME coupling has been demonstrated in a variety of multiferroic heterostructures, including bulk magnetic on ferro/piezoelectric multiferroic heterostructures, magnetic film on ferro/piezoelectric slab multiferroic heterostructures, thin film multiferroic heterostructures, etc. Different multiferroic devices have been demonstrated, which include magnetic sensors, energy harvesters, and voltage tunable multiferroic RF/microwave devices which are compact, lightweight, and power efficient. In this progress report, we cover the most recent progress on multiferroic heterostructures and devices with a focus on voltage tunable multiferroic heterostructures and devices with strong converse ME coupling. Recent progress on magnetic-field tunable RF/microwave devices are also covered, including novel non-reciprocal tunable bandpass filters with ultra wideband isolation, compact, low loss and high power handling phase shifters, etc. These novel tunable multiferroic heterostructures and devices and tunable magnetic devices provide great opportunities for next generation reconfigurable RF/microwave communication systems and radars, Spintronics, magnetic field sensing, etc.

We propose a new design of a gain enhanced EDFA for WDM applications by inserting a wavelength division multiplexing (WDM) filter (with periodic multiple pass band wavelengths coinciding with the ITU channel grid) and an isolator within the EDFA. It is shown that by placing the filter and isolator combination at a distance from the input end of about 30 % of the total length of the EDF, it is possible to achieve about 10 dB improvement in gain and a reduction of about 2 dB in noise figure compared to the case without the filter and isolator. Such an improved EDFA design should be of interest in fiber optic communication systems employing wavelength division multiplexing.

The isolators for high magnetic field facility insulate the helium outlets of the High Temperature Superconducting current leads, which can be at up to 25kV. To evaluate the electrical performance, partial discharge (PD) test was performed in air and helium pressure environment under 16kV alternate current (AC) voltage. To reduce the influence of background noise on PD testing results, narrowband noise was removed by using properly tuned notch filters. The testing results indicate the PD valve of the isolator for high magnetic field facility is lower than allowable valve.