The efficiency of integrated acousto-optic (AO) modulators with different optical penetration depths fabricated on 128-deg-rotated Y-cut X-propagation lithium niobate (128-deg YX-LiNbO3) is analyzed theoretically for the first time by determining the overlap integral between the optical and acoustic field distribution. The results show that the smaller the optical penetration depth is, the higher the optimum surface-acoustic-wave (SAW) frequency and diffraction efficiency and the larger the bandwidth will be. Compared with TM-polarized light, TE-polarized light offers better performance for modulation. However, for a well-concentrated optical waveguide, TM-polarized light is attractive for AO modulators, which employ a single SAW.
In this paper, we present a new theoretical model for the design of acoustical waveguides in the guided acousto-optic devices. The electromechanical coupling coefficient and the velocity in the acoustical in the acoustical waveguide are analyzed for different waveguide thicknesses. Some valuable results for the design of acousto-optic devices are obtained.
This paper presents a novel micro injector, by which microfluidic delivery, transport and control can be digitally realized in femtoliter scale. The microinjection is based on a new principle that the micropipette is actuated by an actuator, which is located outside the micropipette and may have macro scale dimensions, moving in such a manner that its acceleration changes. When the acceleration is small, the liquid moves along with the pipette; while, when the acceleration becomes large enough, the liquid flows relative to the micropipette. The validity of the presented principle is verified by experiment. Digital microinjection has been realized, particularly under conditions that neither micro moving parts nor embedded micro electric circuits are necessary, hence greatly simplifying the structure and reducing the cost. The microfluidic system can work normally over a rather wide range, even though where very large resistance to flow exists. The amount of injected fluid material may reach an ultra high resolution of the order of femtoliters. The kinds of the fluid materials that can be injected include conventional liquids as well as solid powders, pastes, and other substances of similar characteristics. Furthermore, the digital femtoliter microinjector can be expected for making nano particles.
A new non-communication optical fiber--Multimode Tapered Optical Fiber (MTOF) is designed for Desktop Rapid Prototyping System(DRPS), which delivers much greater output energy than non-MTOF of the same output diameter. Its transmission ratio much increased. The DRPS' process is introduced, followed by the choose and design of MTOF, coupling and focusing of UV light. MTOF has some advantages, such as flexibility,low cost,high efficiency. The application of MTOF in DRPS that requires low cost will make concrete fundamental for populating the system.
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