Coaxial jet electrospray is a technique to generate microencapsules, which uses electric forces to create a coaxial microjet from two immiscible liquids. Compound droplets with narrow size distribution are produced after the jet breaks up. In this paper, the spraying modes are investigated experimentally with proper flow rates of the inner and outer liquids. Ethanol/glycerol/tween mixture ͑outer liquid͒ and cooking oil ͑inner liquid͒ are fed into the gap between outer and inner capillaries and the inner capillary, respectively. The spraying modes presented in our experiments are "dripping mode," "dripping mode in spindle," "cone-jet mode," "pulse mode in cone," and "multijets mode" sequentially, as the applied voltage increases. The region of stable cone-jet mode extends with decrease of the outer liquid flow rate and increase of the inner one. It is found that the spray phenomena are mainly determined by properties of the outer liquid, which is viscous and electric conductive enough. A rudimentary physical model is developed, in which both the viscosity and liquid interface tension are taken into account.

This paper presents a study of sea-water monopole antenna at very high frequency (VHF) band for maritime wireless communications. The sea-water monopole antenna consists of a feeding probe and a sea-water cylinder held by a clear acrylic tube. The feeding probe is loaded with a disk on the top to improve the excitation of TM mode. A theoretical study of the sea-water monopole antenna based on the three-term theory is presented, which has not appeared in literature. Commercial software packages ANSYS HFSS and FEKO are used to simulate this antenna. Experimental results of a fabricated sea-water monopole antenna with a radius of 50 mm show reasonably good agreement with theoretical predictions. Measurement shows that the proposed seawater antenna has high radiation efficiency. Meanwhile, due to the transparency and liquidity of sea water, the proposed antenna is almost optically transparent and can be easily reconfigurable. The center frequency of the antenna is tunable by lengthening or shortening the water cylinder, while the bandwidth of the antenna can be adjusted by widening or narrowing the water cylinder.

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We propose a scheme that can generate tunable optomechanical induced transparency (OMIT) in a hybrid piezo-optomechanical cavity system. The system is constituted of a high quality planar distributed Bragg reflectors (DBR) cavity, which the quality is improved by an embedded submicrometer three-dimensional Gaussian-shaped defect. Moreover, the interdigitated transducers (IDTs) are fabricated on the surface of the cavity to generate the surface acoustic waves (SAW). Here, the DBR cavity structure modified with the embedded Gaussian-shaped defect is proposed by F.Ding et al., relative to the traditional DBR structures with the same number of mirror pairs, the quality factor of this design can be effectively improved by nearly two orders, which can exceed 10 5 [1]. We show that when a strong pump optical field and a weak probe optical field are applied to the hybrid cavity system simultaneously, at the presence of the SAW, a transmission window can be obtained in the weak output probe field. This phenomenon arises because that under the actuation of the SAW, the upper Bragg mirrors is vibrated as a bulk acoustic resonator(BAR). Then the two-level system formed by the energy levels of the DBR cavity is turned into a standard three-level optomechanical cavity system, which is formed by the energy levels of the DBR cavity and the BAR. Under the quantum interference between different energy-level pathways, the optomechanically induced transparency (OMIT) occurs, as a result, the transmission window is observed in the weak output probe field. Inversely, without the actuation of the SAW, the transmission window disappears. Our scheme can be applied in the fields of optical switches and quantum information processing in solid-state quantum systems.